/**
 * bundle.css — 自动生成,请勿直接编辑
 * 源文件: variables.css + common.css + components.css
 * 构建时间: 2026-05-14T05:24:49.728Z
 */

/* ===== source: variables.css ===== */
/**
 * CSS Variables - 主题色彩与设计令牌
 * 元思维交互式编程学习平台
 * v2 视觉刷新: 收敛配色、提升对比度、统一字体栈
 */

:root {
    /* ===== 品牌主色族 (CTA / 强调) ===== */
    --primary: #10b981;
    --primary-dark: #047857;
    --primary-light: #6ee7b7;
    --primary-soft: #ecfdf5;
    --primary-rgb: 16, 185, 129;

    /* ===== 辅助强调色 (重点行动) ===== */
    --accent: #f97316;
    --accent-dark: #c2410c;
    --accent-light: #fdba74;
    --accent-soft: #fff7ed;
    --accent-rgb: 249, 115, 22;

    /* ===== 信息色 (蓝紫降级为信息态) ===== */
    --secondary: #3b82f6;
    --secondary-dark: #2563eb;
    --secondary-light: #93c5fd;
    --secondary-rgb: 59, 130, 246;

    /* ===== 学科色 (仅用于学科标签,不污染 CTA) ===== */
    --subject-math: #f97316;
    --subject-physics: #0d9488;
    --subject-code: #10b981;
    --subject-cs: #6366f1;

    /* ===== 语义色 ===== */
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --info: #3b82f6;

    /* ===== 背景色 ===== */
    --bg-primary: #f8fafc;
    --bg-secondary: #f1f5f9;
    --bg-tertiary: #e2e8f0;
    --bg-card: rgba(255, 255, 255, 0.92);
    --bg-glass: rgba(255, 255, 255, 0.85);
    --bg-overlay: rgba(15, 23, 42, 0.45);

    /* ===== 文字色 (提升对比度至 WCAG AA) ===== */
    --text-primary: #0f172a;
    --text-secondary: #334155;
    --text-muted: #64748b;
    --text-disabled: #94a3b8;
    --text-inverse: #f8fafc;
    --text-link: var(--primary-dark);
    --text-link-hover: var(--primary);

    /* ===== 边框色 ===== */
    --border-default: rgba(15, 23, 42, 0.12);
    --border-light: rgba(15, 23, 42, 0.06);
    --border-strong: rgba(15, 23, 42, 0.2);
    --border-focus: var(--primary);

    /* ===== 阴影 ===== */
    --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
    --shadow-md: 0 4px 6px rgba(15, 23, 42, 0.08);
    --shadow-lg: 0 10px 25px rgba(15, 23, 42, 0.1);
    --shadow-xl: 0 20px 40px rgba(15, 23, 42, 0.12);
    --shadow-primary: 0 6px 20px rgba(var(--primary-rgb), 0.22);
    --shadow-accent: 0 6px 20px rgba(var(--accent-rgb), 0.22);
    --shadow-focus: 0 0 0 3px rgba(var(--primary-rgb), 0.35);
    --shadow-focus-accent: 0 0 0 3px rgba(var(--accent-rgb), 0.35);

    /* ===== 圆角 ===== */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;

    /* ===== 间距系统 (基于 4px) ===== */
    --spacing-0: 0;
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;
    --spacing-24: 6rem;

    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    --spacing-4xl: 6rem;

    --section-padding-y: var(--spacing-16);
    --section-padding-y-mobile: var(--spacing-10);
    --container-padding-x: var(--spacing-6);
    --container-padding-x-mobile: var(--spacing-4);

    /* ===== 字体 ===== */
    --font-sans: 'PingFang SC', 'HarmonyOS Sans SC', 'Microsoft YaHei',
                 'Noto Sans CJK SC', system-ui, -apple-system,
                 BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-display: 'PingFang SC', 'HarmonyOS Sans SC', 'Microsoft YaHei',
                    'Noto Sans CJK SC', system-ui, -apple-system,
                    BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Cascadia Code', 'Fira Code',
                 'SF Mono', Consolas, Monaco, monospace;

    /* ===== 字号 ===== */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;

    /* ===== 动画 ===== */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    --transition-bounce: 0.3s cubic-bezier(0.4, 0, 0.2, 1);

    /* ===== 层级 ===== */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-modal: 500;
    --z-toast: 600;
    --z-tooltip: 700;
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
    :root {
        --transition-fast: 0s;
        --transition-normal: 0s;
        --transition-slow: 0s;
        --transition-bounce: 0s;
    }
}


/* ===== source: common.css ===== */
/**
 * Common Styles - 通用基础样式
 * 元思维交互式编程学习平台
 */

/* ===== 重置与基础 ===== */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
}

/* ===== 渐变背景 ===== */
.gradient-bg {
    background: linear-gradient(135deg, #f8fafc 0%, #f1f5f9 50%, #ede9fe 100%);
}

.bg-gradient-animated {
    background: linear-gradient(-45deg, #f8fafc, #f0f4ff, #f0fdf4, #faf5ff);
    background-size: 400% 400%;
    animation: gradientBG 15s ease infinite;
}

@keyframes gradientBG {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

/* ===== 玻璃态效果 ===== */
.glass {
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-default);
}

.glass-strong {
    background: rgba(255, 255, 255, 0.97);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-default);
}

/* ===== 渐变文字 (v2: 品牌色收敛,移除蓝紫调) ===== */
.text-gradient {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 50%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.text-gradient-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.text-gradient-light {
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-muted) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ===== 链接样式 ===== */
a {
    color: inherit;
    text-decoration: none;
    transition: var(--transition-fast);
}

a:hover {
    color: var(--primary);
}

/* ===== 选中样式 ===== */
::selection {
    background: rgba(var(--primary-rgb), 0.2);
    color: #1e293b;
}

/* ===== 滚动条样式 ===== */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: rgba(0, 0, 0, 0.04);
}

::-webkit-scrollbar-thumb {
    background: rgba(0, 0, 0, 0.15);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: rgba(0, 0, 0, 0.25);
}

/* ===== 工具类 ===== */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.truncate {
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* 减少动画 */
@media (prefers-reduced-motion: reduce) {
    .bg-gradient-animated {
        animation: none;
    }
}

/* ===== 光晕效果 (v2 削弱: blur 80→40, opacity 减半, 移动端关闭) ===== */
.glow-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(40px);
    opacity: 0.08;
    animation: pulseGlow 10s ease-in-out infinite;
    will-change: transform, opacity;
    pointer-events: none;
}

@keyframes pulseGlow {
    0%, 100% {
        transform: scale(1);
        opacity: 0.05;
    }
    50% {
        transform: scale(1.15);
        opacity: 0.08;
    }
}

/* 中低端移动端:关闭光晕(blur 在合成线程上昂贵) */
@media (max-width: 640px) {
    .glow-orb {
        display: none;
    }
}

@media (prefers-reduced-motion: reduce) {
    .glow-orb {
        animation: none;
    }
}

/* ===== 代码装饰 ===== */
.code-decoration {
    font-family: var(--font-mono);
    color: var(--primary);
    opacity: 0.1;
    font-size: 12px;
    line-height: 1.4;
    white-space: pre;
    position: absolute;
    pointer-events: none;
    user-select: none;
}

/* ===== 入场动画 (v2: 距离与时长收敛,降低 GPU 负担) ===== */
.fade-in-up {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 0.6s ease-out forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.delay-1 { animation-delay: 0.1s; }
.delay-2 { animation-delay: 0.2s; }
.delay-3 { animation-delay: 0.3s; }
.delay-4 { animation-delay: 0.4s; }
.delay-5 { animation-delay: 0.5s; }

@media (prefers-reduced-motion: reduce) {
    .fade-in-up {
        opacity: 1;
        transform: none;
        animation: none;
    }
}

/* ===== 加载动画 ===== */
.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-default);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.loading-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 300px;
    gap: var(--spacing-md);
}

/* ===== 响应式隐藏 ===== */
@media (max-width: 640px) {
    .hidden-mobile { display: none !important; }
}

@media (min-width: 641px) {
    .hidden-desktop { display: none !important; }
}

@media (max-width: 768px) {
    .hidden-tablet { display: none !important; }
}


/* ===== source: components.css ===== */
/**
 * Components Styles - 组件样式库
 * 元思维交互式编程学习平台
 */

/* ===== 按钮基础 ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-lg);
    font-size: var(--text-sm);
    font-weight: 500;
    font-family: inherit;
    cursor: pointer;
    border: none;
    transition: var(--transition-bounce);
    text-decoration: none;
    white-space: nowrap;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.btn-sm {
    padding: 0.375rem 0.75rem;
    font-size: var(--text-xs);
}

.btn-lg {
    padding: 0.75rem 1.5rem;
    font-size: var(--text-base);
}

.btn-xl {
    padding: 1rem 2rem;
    font-size: var(--text-lg);
    border-radius: var(--radius-xl);
}

/* ===== 按钮变体 ===== */
.btn-primary {
    background: var(--primary);
    color: white;
    box-shadow: 0 1px 2px rgba(var(--primary-rgb), 0.18), 0 4px 12px rgba(var(--primary-rgb), 0.16);
}

.btn-primary:hover:not(:disabled) {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: 0 2px 4px rgba(var(--primary-rgb), 0.22), 0 6px 18px rgba(var(--primary-rgb), 0.28);
}

.btn-primary:active:not(:disabled) {
    transform: translateY(0);
    box-shadow: 0 1px 2px rgba(var(--primary-rgb), 0.2);
}

.btn-secondary {
    background: rgba(0, 0, 0, 0.04);
    color: var(--text-primary);
    border: 1px solid var(--border-default);
}

.btn-secondary:hover:not(:disabled) {
    background: rgba(0, 0, 0, 0.06);
    border-color: rgba(0, 0, 0, 0.15);
}

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
}

.btn-ghost:hover:not(:disabled) {
    background: rgba(0, 0, 0, 0.04);
    color: var(--text-primary);
}

.btn-success {
    background: linear-gradient(135deg, var(--success) 0%, #059669 100%);
    color: white;
}

.btn-success:hover:not(:disabled) {
    transform: translateY(-2px);
}

.btn-danger {
    background: linear-gradient(135deg, var(--error) 0%, #dc2626 100%);
    color: white;
}

.btn-outline-primary {
    background: transparent;
    color: var(--primary);
    border: 1px solid var(--primary);
}

.btn-outline-primary:hover:not(:disabled) {
    background: rgba(var(--primary-rgb), 0.1);
}

/* 品牌渐变工具类(替换 Tailwind 蓝紫渐变,保持 CTA 一致) */
.bg-gradient-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: #ffffff;
}

.bg-gradient-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary) 100%);
    box-shadow: var(--shadow-primary);
}

/* 渐变文字(品牌色) */
.text-gradient-brand {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* 重点行动按钮(橙色,催促/二级 CTA) */
.btn-accent {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dark) 100%);
    color: white;
    box-shadow: var(--shadow-accent);
}

.btn-accent:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(var(--accent-rgb), 0.55);
}

/* 统一焦点环 - 键盘可达性 */
.btn:focus-visible,
.btn-primary:focus-visible,
.btn-secondary:focus-visible,
.btn-ghost:focus-visible,
.btn-success:focus-visible,
.btn-danger:focus-visible,
.btn-outline-primary:focus-visible,
.btn-accent:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus);
}

.btn-accent:focus-visible {
    box-shadow: var(--shadow-focus-accent);
}

/* ===== 统一品牌标识 ===== */
/* 完整横版 Logo（图标+文字） */
.brand-logo-full {
    height: 38px;
    width: auto;
    max-width: 180px;
    object-fit: contain;
    transition: all var(--transition-fast);
    image-rendering: -webkit-optimize-contrast;
    display: block;
    filter: drop-shadow(0 1px 2px rgba(15, 23, 42, 0.1));
}

.brand-logo-full:hover {
    transform: scale(1.02);
}

.brand-logo-full--sm {
    height: 36px;
    /* 移动端/窄版从 28px 提升 */
    max-width: 160px;
}

.brand-logo-full--lg {
    height: 56px;
    max-width: 240px;
}

/* 方形图标 Logo（仅图标部分，用于小空间） */
.brand-logo {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    flex-shrink: 0;
    transition: transform var(--transition-fast);
}

.brand-logo:hover {
    transform: scale(1.05);
}

.brand-logo svg {
    width: 24px;
    height: 24px;
}

.brand-logo--sm {
    width: 32px;
    height: 32px;
}

.brand-logo--sm svg {
    width: 18px;
    height: 18px;
}

.brand-logo--lg {
    width: 56px;
    height: 56px;
}

.brand-logo--lg svg {
    width: 32px;
    height: 32px;
}

.brand-name {
    font-size: var(--text-xl);
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 50%, var(--accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.brand-name--sm {
    font-size: var(--text-lg);
}

.brand-subtitle {
    font-size: var(--text-xs);
    color: var(--text-muted);
    line-height: 1;
}

.brand-group {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
}

.brand-group:hover .brand-logo {
    transform: scale(1.05);
}

.brand-group:hover .brand-logo-full {
    transform: scale(1.02);
}

.brand-info {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

/* ===== 导航栏 ===== */
.nav {
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-light);
}

.nav--fixed {
    position: fixed;
    left: 0;
    right: 0;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-lg);
    /* 缩小 padding，让大 Logo 撑满视觉 */
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-container--fluid {
    max-width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.nav-logo {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
}

.nav-title {
    font-size: var(--text-xl);
    font-weight: 700;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.nav-link {
    color: var(--text-secondary);
    font-size: var(--text-sm);
    transition: var(--transition-fast);
}

.nav-link:hover {
    color: var(--text-primary);
}

.nav-link.active {
    color: var(--primary);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* 下拉菜单 */
.nav-dropdown {
    position: relative;
}

.nav-dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    margin-top: var(--spacing-sm);
    min-width: 160px;
    background: var(--bg-tertiary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--border-default);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: var(--transition-fast);
    z-index: var(--z-dropdown);
}

.nav-dropdown:hover .nav-dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.nav-dropdown-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-secondary);
    font-size: var(--text-sm);
    transition: var(--transition-fast);
}

.nav-dropdown-item:first-child {
    border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}

.nav-dropdown-item:last-child {
    border-radius: 0 0 var(--radius-lg) var(--radius-lg);
}

.nav-dropdown-item:hover {
    background: rgba(0, 0, 0, 0.04);
    color: var(--text-primary);
}

/* 导航栏分隔线 */
.nav-divider {
    width: 1px;
    height: 20px;
    background: var(--border-default);
    margin: 0 var(--spacing-sm);
}

/* 导航栏返回按钮 */
.nav-back {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--text-secondary);
    font-size: var(--text-sm);
    transition: var(--transition-fast);
}

.nav-back:hover {
    color: var(--text-primary);
}

.nav-back svg {
    width: 20px;
    height: 20px;
}

/* 导航栏页面标题 */
.nav-page-title {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--text-primary);
    max-width: 200px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

/* 移动端菜单 */
.nav-mobile-toggle {
    display: none;
    padding: var(--spacing-sm);
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: var(--transition-fast);
}

.nav-mobile-toggle:hover {
    background: rgba(0, 0, 0, 0.04);
}

.nav-mobile-toggle svg {
    width: 24px;
    height: 24px;
}

/* 移动端菜单 - 覆盖层 (v2: 用 transform/visibility 而非 display 切换,首次开有动画) */
.nav-mobile-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.3);
    z-index: calc(var(--z-sticky) - 1);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), visibility var(--transition-normal);
}

@media (min-width: 769px) {
    .nav-mobile-overlay,
    .nav-mobile-menu {
        display: none;
    }
}

.nav-mobile-overlay.open {
    opacity: 1;
    visibility: visible;
}

/* 移动端菜单 - 侧边抽屉 */
.nav-mobile-menu {
    position: fixed;
    top: 0;
    right: 0;
    width: 280px;
    height: 100vh;
    background: var(--bg-secondary);
    z-index: var(--z-sticky);
    padding: var(--spacing-lg);
    transform: translateX(100%);
    transition: transform var(--transition-normal);
    overflow-y: auto;
    visibility: hidden;
}

.nav-mobile-menu.open {
    transform: translateX(0);
    visibility: visible;
}

/* 超窄屏(360px-)抽屉占满,避免主内容剩余太少 */
@media (max-width: 380px) {
    .nav-mobile-menu {
        width: 100vw;
    }
}

.nav-mobile-menu-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid var(--border-default);
}

.nav-mobile-menu-close {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-md);
}

.nav-mobile-menu-close:hover {
    background: rgba(0, 0, 0, 0.04);
    color: var(--text-primary);
}

.nav-mobile-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    color: var(--text-secondary);
    font-size: var(--text-base);
    border-radius: var(--radius-md);
    transition: var(--transition-fast);
    margin-bottom: var(--spacing-xs);
}

.nav-mobile-link:hover,
.nav-mobile-link.active {
    background: rgba(var(--primary-rgb), 0.1);
    color: var(--primary);
}

.nav-mobile-link svg {
    width: 20px;
    height: 20px;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .nav-mobile-toggle {
        display: flex;
    }

    .nav-actions .hidden-mobile {
        display: none;
    }

    .nav-container {
        padding: var(--spacing-sm) var(--spacing-md);
    }

    .brand-name {
        font-size: var(--text-lg);
    }

    .brand-subtitle {
        display: none;
    }
}

/* ===== 卡片 ===== */
.card {
    background: var(--bg-glass);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-lg);
    transition: var(--transition-bounce);
}

.card-hover:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-interactive {
    cursor: pointer;
}

.card-interactive:hover {
    border-color: rgba(var(--primary-rgb), 0.3);
    background: rgba(0, 0, 0, 0.03);
}

/* 特性卡片 */
.feature-card {
    background: rgba(255, 255, 255, 0.7);
    border: 1px solid var(--border-light);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-lg);
    transition: var(--transition-bounce);
}

.feature-card:hover {
    background: rgba(255, 255, 255, 0.95);
    border-color: rgba(var(--primary-rgb), 0.3);
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    width: 56px;
    height: 56px;
    border-radius: var(--radius-xl);
    background: linear-gradient(135deg, rgba(var(--primary-rgb), 0.18) 0%, rgba(var(--primary-rgb), 0.06) 100%);
    border: 1px solid rgba(var(--primary-rgb), 0.25);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-lg);
}

/* 重点行动主题(橙色)的 feature 卡片 icon 容器 */
.feature-card--accent .feature-icon {
    background: linear-gradient(135deg, rgba(var(--accent-rgb), 0.18) 0%, rgba(var(--accent-rgb), 0.06) 100%);
    border-color: rgba(var(--accent-rgb), 0.25);
}

.feature-card--accent:hover {
    border-color: rgba(var(--accent-rgb), 0.3);
}

/* ===== Profile 页 Hero 摘要 ===== */
.profile-hero__layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: var(--spacing-xl);
    align-items: center;
}

.profile-hero__user {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
}

.profile-hero__avatar {
    width: 80px;
    height: 80px;
    flex-shrink: 0;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: #ffffff;
    font-size: 2rem;
    font-weight: 700;
    box-shadow: var(--shadow-md);
}

.profile-hero__meta {
    flex: 1;
    min-width: 0;
}

.profile-hero__role {
    padding: 4px 12px;
    border-radius: var(--radius-full);
    background: var(--primary-soft);
    color: var(--primary-dark);
    border: 1px solid rgba(var(--primary-rgb), 0.2);
    font-size: var(--text-xs);
    font-weight: 500;
}

.profile-hero__today {
    display: flex;
    align-items: stretch;
    justify-content: space-between;
    gap: var(--spacing-md);
    padding: var(--spacing-lg);
    background: rgba(15, 23, 42, 0.03);
    border-radius: var(--radius-xl);
}

.profile-hero__today-main {
    flex: 1;
    min-width: 0;
}

.profile-hero__today-value {
    font-size: var(--text-3xl);
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.1;
}

.profile-hero__streak {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 0 var(--spacing-md);
    border-left: 1px solid var(--border-default);
    text-align: center;
    min-width: 80px;
}

.profile-hero__streak-value {
    font-size: var(--text-3xl);
    font-weight: 700;
    color: var(--accent-dark);
    line-height: 1.1;
}

@media (max-width: 768px) {
    .profile-hero__layout {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .profile-hero__user {
        gap: var(--spacing-md);
    }
    .profile-hero__avatar {
        width: 64px;
        height: 64px;
        font-size: 1.5rem;
    }
    .profile-hero__today {
        padding: var(--spacing-md);
    }
}

/* 学习日历强度色块图例 */
.calendar-cell {
    display: inline-block;
    width: 12px;
    height: 12px;
    border-radius: 3px;
}
.calendar-cell--0 { background: #e2e8f0; }
.calendar-cell--1 { background: #bbf7d0; }
.calendar-cell--2 { background: #86efac; }
.calendar-cell--3 { background: #4ade80; }
.calendar-cell--4 { background: #22c55e; }

/* ===== Hero 统计区(landing) ===== */
.hero-stats {
    max-width: 720px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr auto 1fr auto 1fr;
    align-items: center;
    gap: var(--spacing-lg);
    padding: var(--spacing-xl) var(--spacing-lg);
    background: rgba(255, 255, 255, 0.55);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-2xl);
    box-shadow: var(--shadow-md);
}

.hero-stats__item {
    text-align: center;
}

.hero-stats__divider {
    width: 1px;
    align-self: stretch;
    background: linear-gradient(180deg, transparent, var(--border-default) 30%, var(--border-default) 70%, transparent);
}

@media (max-width: 640px) {
    .hero-stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
        padding: var(--spacing-lg);
    }
    .hero-stats__divider {
        display: none;
    }
}

/* ===== Hero 区 badge 标签 ===== */
.hero-badge {
    padding: 6px 14px;
    border-radius: var(--radius-full);
    font-size: var(--text-sm);
    font-weight: 500;
    border: 1px solid;
    display: inline-block;
}

.hero-badge--primary {
    background: var(--primary-soft);
    color: var(--primary-dark);
    border-color: rgba(var(--primary-rgb), 0.25);
}

.hero-badge--accent {
    background: var(--accent-soft);
    color: var(--accent-dark);
    border-color: rgba(var(--accent-rgb), 0.25);
}

.hero-badge--neutral {
    background: rgba(15, 23, 42, 0.04);
    color: var(--text-secondary);
    border-color: var(--border-default);
}

/* ===== 登录弹窗 卖点列表 icon ===== */
.auth-feature-icon {
    padding: 10px;
    border-radius: var(--radius-xl);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    transition: background-color var(--transition-fast), color var(--transition-fast);
    ring-width: 1px;
    box-shadow: inset 0 0 0 1px rgba(15, 23, 42, 0.04);
}

.auth-feature-icon--primary {
    background: rgba(var(--primary-rgb), 0.1);
    color: var(--primary-dark);
    box-shadow: inset 0 0 0 1px rgba(var(--primary-rgb), 0.2);
}

.group:hover .auth-feature-icon--primary {
    background: rgba(var(--primary-rgb), 0.18);
}

.auth-feature-icon--accent {
    background: rgba(var(--accent-rgb), 0.1);
    color: var(--accent-dark);
    box-shadow: inset 0 0 0 1px rgba(var(--accent-rgb), 0.2);
}

.group:hover .auth-feature-icon--accent {
    background: rgba(var(--accent-rgb), 0.18);
}

/* ===== 课程分类切换标签 (category tab) ===== */
.course-cat-tab {
    padding: 8px 16px;
    border-radius: var(--radius-full);
    background: rgba(15, 23, 42, 0.04);
    color: var(--text-secondary);
    font-size: var(--text-sm);
    font-weight: 500;
    border: 1px solid transparent;
    cursor: pointer;
    transition: var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.course-cat-tab:hover {
    background: rgba(15, 23, 42, 0.07);
    color: var(--text-primary);
}

.course-cat-tab--active {
    background: var(--primary-soft);
    color: var(--primary-dark);
    border-color: rgba(var(--primary-rgb), 0.25);
    font-weight: 600;
}

.course-cat-tab--active:hover {
    background: rgba(var(--primary-rgb), 0.15);
}

.course-cat-tab__count {
    font-size: 11px;
    padding: 1px 7px;
    border-radius: var(--radius-full);
    background: rgba(15, 23, 42, 0.08);
    color: var(--text-muted);
    font-weight: 500;
}

.course-cat-tab--active .course-cat-tab__count {
    background: rgba(var(--primary-rgb), 0.18);
    color: var(--primary-dark);
}

.course-cat-tab:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus);
}

/* ===== 课程类型卡片 (course type card) ===== */
.course-type-card {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: rgba(255, 255, 255, 0.6);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: var(--transition-bounce);
    position: relative;
    overflow: hidden;
}

.course-type-card:hover {
    background: #ffffff;
    border-color: rgba(var(--primary-rgb), 0.3);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.course-type-card--active {
    background: linear-gradient(135deg,
        rgba(var(--primary-rgb), 0.08) 0%,
        rgba(255, 255, 255, 0.95) 60%);
    border-color: rgba(var(--primary-rgb), 0.4);
    box-shadow: 0 4px 12px rgba(var(--primary-rgb), 0.1);
}

.course-type-card--active::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--primary), var(--primary-dark));
}

.course-type-card__icon {
    width: 44px;
    height: 44px;
    flex-shrink: 0;
    border-radius: var(--radius-md);
    background: var(--primary-soft);
    color: var(--primary-dark);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-sm);
    font-weight: 700;
    border: 1px solid rgba(var(--primary-rgb), 0.15);
}

.course-type-card--active .course-type-card__icon {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #ffffff;
    border-color: transparent;
}

.course-type-card__body {
    flex: 1;
    min-width: 0;
}

.course-type-card__title {
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.3;
    margin: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.course-type-card--active .course-type-card__title {
    color: var(--primary-dark);
}

.course-type-card__hint {
    font-size: 11px;
    color: var(--text-muted);
    margin: 2px 0 0 0;
}

.course-type-card--active .course-type-card__hint {
    color: var(--primary);
}

.course-type-card__check {
    width: 18px;
    height: 18px;
    color: var(--primary-dark);
    flex-shrink: 0;
}

.course-type-card:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus);
}

/* ============================================
   Learning Path - 创意学习路径布局 (Duolingo 启发)
   ============================================ */

.learning-path {
    --path-cols: 5;
    --path-gap: 28px;
    --node-size: 92px;
    --connector-color: rgba(var(--primary-rgb), 0.18);

    position: relative;
    display: grid;
    grid-template-columns: repeat(var(--path-cols), minmax(0, 1fr));
    gap: var(--path-gap);
    padding: var(--spacing-2xl) var(--spacing-md);
    background:
        radial-gradient(circle at 20% 10%, rgba(var(--primary-rgb), 0.05) 0%, transparent 40%),
        radial-gradient(circle at 80% 80%, rgba(var(--accent-rgb), 0.04) 0%, transparent 40%);
    border-radius: var(--radius-2xl);
}

/* 单元分组分隔条 - 占满整行 */
.path-section-header {
    grid-column: 1 / -1;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0 var(--spacing-sm);
    padding-left: var(--spacing-md);
}

.path-section-header__badge {
    padding: 4px 12px;
    border-radius: var(--radius-full);
    background: var(--primary-soft);
    color: var(--primary-dark);
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    border: 1px solid rgba(var(--primary-rgb), 0.2);
    flex-shrink: 0;
}

.path-section-header__title {
    font-size: var(--text-base);
    font-weight: 600;
    color: var(--text-primary);
    white-space: nowrap;
}

.path-section-header__line {
    flex: 1;
    height: 1px;
    background: linear-gradient(90deg, var(--border-default), transparent);
}

/* 节点位置(由 JS 注入 --col 值控制) */
.lesson-node-wrapper {
    grid-column: var(--col) / span 1;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
    position: relative;
    padding: 8px 4px;
    animation: nodeFadeIn 0.5s ease-out backwards;
    animation-delay: var(--anim-delay, 0s);
}

@keyframes nodeFadeIn {
    from { opacity: 0; transform: translateY(12px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (prefers-reduced-motion: reduce) {
    .lesson-node-wrapper { animation: none; }
}

/* v3: 删除连接线 — zigzag 节点本身已构成视觉路径,
       且 R→L 行的连接线方向反转逻辑过于复杂,容易出现错位 */

/* 节点本体 */
.lesson-node {
    position: relative;
    z-index: 1;
    width: var(--node-size);
    height: var(--node-size);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-mono);
    font-size: var(--text-2xl);
    font-weight: 700;
    cursor: pointer;
    transition: var(--transition-bounce);
    border: 4px solid transparent;
    background: #ffffff;
    color: var(--text-secondary);
    box-shadow:
        0 6px 14px -4px rgba(15, 23, 42, 0.12),
        inset 0 -4px 0 rgba(15, 23, 42, 0.06);
}

.lesson-node:focus-visible {
    outline: none;
    box-shadow:
        0 6px 14px -4px rgba(15, 23, 42, 0.12),
        inset 0 -4px 0 rgba(15, 23, 42, 0.06),
        var(--shadow-focus);
}

.lesson-node:hover {
    transform: translateY(-2px) scale(1.04);
}

/* 完成态 - 绿色实心 + 白色对勾 */
.lesson-node--completed {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #ffffff;
    border-color: rgba(var(--primary-rgb), 0.25);
    box-shadow:
        0 6px 14px -4px rgba(var(--primary-rgb), 0.4),
        inset 0 -4px 0 rgba(0, 0, 0, 0.15);
}

.lesson-node--completed::after {
    content: '';
    position: absolute;
    inset: 0;
    border-radius: 50%;
    background: radial-gradient(circle, transparent 60%, rgba(var(--primary-rgb), 0.2) 100%);
}

/* 当前可学态 - 橙色实心 + 数字 + 脉冲光环 */
.lesson-node--current {
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    color: #ffffff;
    border-color: rgba(var(--accent-rgb), 0.3);
    box-shadow:
        0 6px 14px -4px rgba(var(--accent-rgb), 0.5),
        inset 0 -4px 0 rgba(0, 0, 0, 0.15);
    animation: lessonNodePulse 2.2s ease-in-out infinite;
}

@keyframes lessonNodePulse {
    0%, 100% {
        box-shadow:
            0 6px 14px -4px rgba(var(--accent-rgb), 0.5),
            inset 0 -4px 0 rgba(0, 0, 0, 0.15),
            0 0 0 0 rgba(var(--accent-rgb), 0.45);
    }
    50% {
        box-shadow:
            0 6px 14px -4px rgba(var(--accent-rgb), 0.5),
            inset 0 -4px 0 rgba(0, 0, 0, 0.15),
            0 0 0 12px rgba(var(--accent-rgb), 0);
    }
}

@media (prefers-reduced-motion: reduce) {
    .lesson-node--current { animation: none; }
}

/* 可学态(已登录,非当前但解锁) */
.lesson-node--available {
    background: #ffffff;
    color: var(--primary-dark);
    border-color: rgba(var(--primary-rgb), 0.5);
}

.lesson-node--available:hover {
    background: var(--primary-soft);
}

/* 锁定态(已登录但上一节未完成) */
.lesson-node--locked {
    background: rgba(15, 23, 42, 0.05);
    color: var(--text-muted);
    border-color: rgba(15, 23, 42, 0.08);
    cursor: not-allowed;
    box-shadow:
        inset 0 -4px 0 rgba(15, 23, 42, 0.04);
}

.lesson-node--locked:hover {
    transform: none;
}

/* 需注册态(未登录) - 虚线橙描边 + 锁 */
.lesson-node--login-required {
    background: #ffffff;
    color: var(--accent-dark);
    border-style: dashed;
    border-color: rgba(var(--accent-rgb), 0.45);
    box-shadow:
        0 4px 10px -4px rgba(var(--accent-rgb), 0.25),
        inset 0 -4px 0 rgba(var(--accent-rgb), 0.08);
}

.lesson-node--login-required:hover {
    border-style: solid;
    border-color: var(--accent);
    color: var(--accent-dark);
}

/* 节点内的 ✓ icon(完成态) */
.lesson-node__check {
    width: 38px;
    height: 38px;
    stroke-width: 3.5;
}

/* 节点内的 🔒 icon(锁定/需注册态) - 在数字下面小角标 */
.lesson-node__lock {
    position: absolute;
    bottom: -2px;
    right: -2px;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    background: #ffffff;
    border: 2px solid currentColor;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 2px 4px rgba(15, 23, 42, 0.15);
}

.lesson-node__lock svg {
    width: 12px;
    height: 12px;
}

.lesson-node--locked .lesson-node__lock,
.lesson-node--login-required .lesson-node__lock {
    color: currentColor;
}

/* 当前节点的 "START" 飘带 */
.lesson-node__start-flag {
    position: absolute;
    top: -28px;
    left: 50%;
    transform: translateX(-50%);
    padding: 4px 12px;
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    color: #ffffff;
    font-size: 10px;
    font-weight: 700;
    letter-spacing: 0.06em;
    border-radius: var(--radius-full);
    box-shadow: 0 4px 10px -2px rgba(var(--accent-rgb), 0.4);
    white-space: nowrap;
    z-index: 2;
}

.lesson-node__start-flag::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 50%;
    transform: translateX(-50%) rotate(45deg);
    width: 8px;
    height: 8px;
    background: var(--accent-dark);
}

/* 节点下方的标题/章节号 */
.lesson-node__label {
    text-align: center;
    max-width: 130px;
    font-size: var(--text-xs);
    line-height: 1.35;
    color: var(--text-secondary);
}

.lesson-node__label-num {
    display: block;
    font-size: 10px;
    color: var(--text-muted);
    margin-bottom: 2px;
    font-weight: 500;
}

.lesson-node__label-title {
    font-weight: 500;
    color: var(--text-primary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.lesson-node-wrapper--current .lesson-node__label-title {
    color: var(--accent-dark);
    font-weight: 600;
}

/* hover 浮卡(显示完整标题 / 状态 / 行动提示) */
.lesson-node__tooltip {
    position: absolute;
    bottom: calc(100% + 12px);
    left: 50%;
    transform: translateX(-50%) translateY(8px);
    min-width: 200px;
    max-width: 240px;
    padding: 12px 14px;
    background: #ffffff;
    border: 1px solid var(--border-default);
    border-radius: var(--radius-lg);
    box-shadow: 0 12px 28px -8px rgba(15, 23, 42, 0.2);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.18s, transform 0.18s, visibility 0.18s;
    z-index: 10;
}

.lesson-node-wrapper:hover .lesson-node__tooltip,
.lesson-node-wrapper:focus-within .lesson-node__tooltip {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.lesson-node__tooltip::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 0;
    border: 6px solid transparent;
    border-top-color: #ffffff;
}

.lesson-node__tooltip-title {
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
    line-height: 1.4;
}

.lesson-node__tooltip-meta {
    font-size: 11px;
    color: var(--text-muted);
    margin-bottom: 8px;
}

.lesson-node__tooltip-cta {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    font-size: var(--text-xs);
    font-weight: 600;
    color: var(--primary-dark);
}

.lesson-node-wrapper--login-required .lesson-node__tooltip-cta {
    color: var(--accent-dark);
}

.lesson-node-wrapper--locked .lesson-node__tooltip-cta {
    color: var(--text-muted);
}

/* 学科 hero 进度卡 */
.path-hero {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-xl);
    padding: var(--spacing-lg) var(--spacing-xl);
    background:
        linear-gradient(135deg, var(--primary-soft) 0%, rgba(255, 255, 255, 0.95) 60%);
    border: 1px solid rgba(var(--primary-rgb), 0.15);
    border-radius: var(--radius-2xl);
    margin-bottom: var(--spacing-lg);
    position: relative;
    overflow: hidden;
}

.path-hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -10%;
    width: 320px;
    height: 320px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(var(--primary-rgb), 0.12) 0%, transparent 70%);
    pointer-events: none;
}

.path-hero__info {
    flex: 1;
    min-width: 0;
    position: relative;
}

.path-hero__title {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 6px;
}

.path-hero__sub {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    margin: 0 0 var(--spacing-md);
}

.path-hero__stats {
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    flex-wrap: wrap;
}

.path-hero__stat {
    display: flex;
    align-items: baseline;
    gap: 6px;
}

.path-hero__stat-num {
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--primary-dark);
    font-family: var(--font-mono);
}

.path-hero__stat-label {
    font-size: var(--text-xs);
    color: var(--text-muted);
}

.path-hero__ring {
    position: relative;
    width: 96px;
    height: 96px;
    flex-shrink: 0;
}

.path-hero__ring svg {
    width: 100%;
    height: 100%;
    transform: rotate(-90deg);
}

.path-hero__ring-text {
    position: absolute;
    inset: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--primary-dark);
    font-family: var(--font-mono);
}

/* 右下浮按钮:回到当前进度 */
.path-jump-current {
    position: fixed;
    bottom: 100px;
    right: 24px;
    z-index: var(--z-sticky);
    display: none;
    align-items: center;
    gap: 6px;
    padding: 10px 16px;
    background: linear-gradient(135deg, var(--accent), var(--accent-dark));
    color: #ffffff;
    border: none;
    border-radius: var(--radius-full);
    box-shadow: 0 8px 20px -4px rgba(var(--accent-rgb), 0.5);
    cursor: pointer;
    font-size: var(--text-sm);
    font-weight: 600;
    transition: var(--transition-bounce);
}

.path-jump-current.is-visible {
    display: inline-flex;
    animation: pathJumpFadeIn 0.3s ease-out;
}

@keyframes pathJumpFadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.path-jump-current:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 24px -4px rgba(var(--accent-rgb), 0.55);
}

.path-jump-current svg {
    width: 14px;
    height: 14px;
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
    .learning-path {
        --path-cols: 4;
        --node-size: 84px;
    }
}

@media (max-width: 768px) {
    .learning-path {
        --path-cols: 3;
        --node-size: 76px;
        --path-gap: 22px;
        padding: var(--spacing-xl) var(--spacing-sm);
    }
    .lesson-node {
        font-size: var(--text-xl);
        border-width: 3px;
    }
    .lesson-node__label {
        max-width: 110px;
    }
    .lesson-node__tooltip {
        min-width: 180px;
    }
    .path-hero {
        flex-direction: column;
        align-items: flex-start;
        padding: var(--spacing-md) var(--spacing-lg);
    }
    .path-hero__ring {
        align-self: center;
    }
}

@media (max-width: 480px) {
    .learning-path {
        --path-cols: 2;
        --node-size: 72px;
        --path-gap: 18px;
    }
    .path-jump-current {
        bottom: 90px;
        right: 16px;
        padding: 8px 12px;
        font-size: var(--text-xs);
    }
}

/* ===== 课程章节骨架屏 ===== */
.lesson-skeleton {
    background: rgba(255, 255, 255, 0.7);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    position: relative;
    overflow: hidden;
}

.lesson-skeleton::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(90deg,
        transparent 0%,
        rgba(255, 255, 255, 0.6) 50%,
        transparent 100%);
    transform: translateX(-100%);
    animation: skeletonShimmer 1.6s ease-in-out infinite;
}

.lesson-skeleton__top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-md);
}

.lesson-skeleton__index {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-lg);
    background: rgba(15, 23, 42, 0.06);
}

.lesson-skeleton__badge {
    width: 60px;
    height: 22px;
    border-radius: var(--radius-full);
    background: rgba(15, 23, 42, 0.05);
}

.lesson-skeleton__line {
    height: 14px;
    background: rgba(15, 23, 42, 0.06);
    border-radius: 4px;
    margin-bottom: 8px;
}

.lesson-skeleton__line--short {
    width: 50%;
}

.lesson-skeleton__bar {
    height: 4px;
    background: rgba(15, 23, 42, 0.06);
    border-radius: 2px;
    margin-top: var(--spacing-lg);
}

/* ===== 未登录提示卡(强化注册 CTA) ===== */
.login-prompt-card {
    background: linear-gradient(135deg,
        var(--primary-soft) 0%,
        rgba(255, 255, 255, 0.95) 60%);
    border: 1px solid rgba(var(--primary-rgb), 0.2);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.login-prompt-card::before {
    content: '';
    position: absolute;
    top: -40%;
    right: -10%;
    width: 240px;
    height: 240px;
    border-radius: 50%;
    background: radial-gradient(circle,
        rgba(var(--primary-rgb), 0.18) 0%,
        transparent 70%);
    pointer-events: none;
}

.login-prompt-card__icon {
    width: 56px;
    height: 56px;
    margin: 0 auto var(--spacing-md);
    border-radius: var(--radius-xl);
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: #ffffff;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 8px 24px -8px rgba(var(--primary-rgb), 0.5);
    position: relative;
}

.login-prompt-card__icon svg {
    width: 28px;
    height: 28px;
}

.login-prompt-card__title {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    position: relative;
}

.login-prompt-card__desc {
    color: var(--text-secondary);
    font-size: var(--text-sm);
    max-width: 32em;
    margin: 0 auto var(--spacing-lg);
    position: relative;
}

.login-prompt-card__actions {
    display: inline-flex;
    gap: var(--spacing-sm);
    position: relative;
}

/* ===== 课程章节卡片 (lesson card) ===== */
.lesson-card {
    position: relative;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-light);
    border-radius: var(--radius-xl);
    padding: var(--spacing-lg);
    transition: transform var(--transition-bounce),
                box-shadow var(--transition-bounce),
                border-color var(--transition-fast);
    cursor: pointer;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

.lesson-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    height: 3px;
    width: 100%;
    background: linear-gradient(90deg, var(--primary) 0%, var(--primary-dark) 100%);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition-normal);
}

.lesson-card:hover {
    transform: translateY(-4px);
    border-color: rgba(var(--primary-rgb), 0.35);
    box-shadow: 0 12px 28px -8px rgba(15, 23, 42, 0.12),
                0 0 0 1px rgba(var(--primary-rgb), 0.1);
}

.lesson-card:hover::before {
    transform: scaleX(1);
}

/* 完成态 */
.lesson-card--completed {
    border-color: rgba(var(--primary-rgb), 0.25);
    background: linear-gradient(135deg,
        rgba(var(--primary-rgb), 0.04) 0%,
        rgba(255, 255, 255, 0.9) 60%);
}

.lesson-card--completed::before {
    transform: scaleX(1);
    background: var(--primary);
}

/* 锁定态(未登录或上一节未完成) */
.lesson-card--locked {
    cursor: not-allowed;
    background: rgba(241, 245, 249, 0.7);
    border-style: dashed;
}

.lesson-card--locked:hover {
    transform: none;
    border-color: rgba(var(--primary-rgb), 0.4);
    box-shadow: 0 4px 12px rgba(15, 23, 42, 0.06);
}

.lesson-card--locked::before {
    background: linear-gradient(90deg, var(--accent) 0%, var(--accent-dark) 100%);
}

.lesson-card--locked:hover::before {
    transform: scaleX(1);
}

/* 章节序号 */
.lesson-card__index {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-mono);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--primary-dark);
    background: var(--primary-soft);
    border: 1px solid rgba(var(--primary-rgb), 0.15);
    flex-shrink: 0;
    transition: var(--transition-fast);
}

.lesson-card--completed .lesson-card__index {
    color: #ffffff;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    border-color: transparent;
    box-shadow: 0 4px 12px rgba(var(--primary-rgb), 0.3);
}

.lesson-card--locked .lesson-card__index {
    color: var(--text-muted);
    background: rgba(15, 23, 42, 0.06);
    border-color: var(--border-default);
}

/* 状态徽章(右上) */
.lesson-card__badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 4px 10px;
    border-radius: var(--radius-full);
    font-size: 11px;
    font-weight: 500;
    line-height: 1;
}

.lesson-card__badge--available {
    background: var(--primary-soft);
    color: var(--primary-dark);
    border: 1px solid rgba(var(--primary-rgb), 0.2);
}

.lesson-card__badge--completed {
    background: rgba(var(--primary-rgb), 0.15);
    color: var(--primary-dark);
    border: 1px solid rgba(var(--primary-rgb), 0.25);
}

.lesson-card__badge--locked {
    background: var(--accent-soft);
    color: var(--accent-dark);
    border: 1px solid rgba(var(--accent-rgb), 0.2);
}

.lesson-card__badge--login-required {
    background: rgba(15, 23, 42, 0.06);
    color: var(--text-secondary);
    border: 1px solid var(--border-default);
}

.lesson-card__badge svg {
    width: 12px;
    height: 12px;
}

/* 标题与描述 */
.lesson-card__title {
    font-size: var(--text-base);
    font-weight: 600;
    color: var(--text-primary);
    margin-top: var(--spacing-md);
    margin-bottom: var(--spacing-xs);
    line-height: 1.4;
    /* 限制 2 行 */
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    min-height: 2.8em;
}

.lesson-card--locked .lesson-card__title {
    color: var(--text-secondary);
}

.lesson-card__meta {
    font-size: var(--text-xs);
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 6px;
}

/* 进度条(完成态显示绿条) */
.lesson-card__progress {
    margin-top: auto;
    padding-top: var(--spacing-md);
}

.lesson-card__progress-bar {
    height: 4px;
    border-radius: 2px;
    background: rgba(15, 23, 42, 0.06);
    overflow: hidden;
    position: relative;
}

.lesson-card__progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary), var(--primary-dark));
    border-radius: inherit;
    transition: width var(--transition-slow);
}

.lesson-card__progress-text {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 6px;
    font-size: var(--text-xs);
    color: var(--text-muted);
}

.lesson-card__progress-text strong {
    color: var(--primary-dark);
    font-weight: 600;
}

/* 锁定态的"点击注册"提示 */
.lesson-card__lock-hint {
    display: flex;
    align-items: center;
    gap: 6px;
    margin-top: auto;
    padding-top: var(--spacing-md);
    font-size: var(--text-xs);
    color: var(--accent-dark);
    font-weight: 500;
}

.lesson-card__lock-hint svg {
    width: 14px;
    height: 14px;
}

/* ===== 交互演示卡片 (demo card) ===== */
.demo-card {
    position: relative;
}

.demo-card__chip {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-sm);
    font-weight: 700;
    flex-shrink: 0;
}

.demo-card__chip--math {
    background: var(--accent-soft);
    color: var(--accent-dark);
}

.demo-card__chip--physics {
    background: #ccfbf1;
    color: #0f766e;
}

.demo-card__chip--code {
    background: var(--primary-soft);
    color: var(--primary-dark);
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    letter-spacing: -0.04em;
}

.demo-card__live {
    margin-left: auto;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 11px;
    font-weight: 500;
    color: var(--text-muted);
    padding: 4px 10px;
    border-radius: var(--radius-full);
    background: rgba(15, 23, 42, 0.04);
    white-space: nowrap;
}

.demo-card__live-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--primary);
    box-shadow: 0 0 0 0 rgba(var(--primary-rgb), 0.55);
    animation: demoLivePulse 2s ease-out infinite;
}

@keyframes demoLivePulse {
    0%   { box-shadow: 0 0 0 0 rgba(var(--primary-rgb), 0.5); }
    70%  { box-shadow: 0 0 0 6px rgba(var(--primary-rgb), 0); }
    100% { box-shadow: 0 0 0 0 rgba(var(--primary-rgb), 0); }
}

@media (prefers-reduced-motion: reduce) {
    .demo-card__live-dot { animation: none; }
}

.demo-card__stage {
    box-shadow: inset 0 0 0 1px rgba(15, 23, 42, 0.04);
}

.demo-card__stage--math {
    background: linear-gradient(135deg, var(--accent-soft) 0%, #fff7ed 100%);
    box-shadow: inset 0 0 0 1px rgba(var(--accent-rgb), 0.12);
}

.demo-card__stage--physics {
    background: linear-gradient(135deg, #f0fdfa 0%, #ecfeff 100%);
    box-shadow: inset 0 0 0 1px rgba(13, 148, 136, 0.12);
}

.demo-card__stage--code {
    background: linear-gradient(135deg, var(--primary-soft) 0%, #f0fdf4 100%);
    box-shadow: inset 0 0 0 1px rgba(var(--primary-rgb), 0.12);
}

/* 课程卡片 - 基础(默认走品牌绿色调) */
.course-card {
    background: linear-gradient(135deg, rgba(var(--primary-rgb), 0.08) 0%, rgba(var(--primary-rgb), 0.02) 100%);
    border: 1px solid rgba(var(--primary-rgb), 0.18);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    transition: var(--transition-normal);
}

.course-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 30px rgba(15, 23, 42, 0.08);
    border-color: rgba(var(--primary-rgb), 0.4);
}

/* 数学课卡片 - 橙色调 */
.course-card--math {
    background: linear-gradient(135deg, rgba(var(--accent-rgb), 0.08) 0%, rgba(var(--accent-rgb), 0.02) 100%);
    border-color: rgba(var(--accent-rgb), 0.18);
}

.course-card--math:hover {
    border-color: rgba(var(--accent-rgb), 0.4);
}

/* 物理课卡片 - 青色调 */
.course-card--physics {
    background: linear-gradient(135deg, rgba(13, 148, 136, 0.08) 0%, rgba(13, 148, 136, 0.02) 100%);
    border-color: rgba(13, 148, 136, 0.18);
}

.course-card--physics:hover {
    border-color: rgba(13, 148, 136, 0.4);
}

/* 编程课卡片 - 沿用 .course-card 默认绿色调 */
.course-card--code {
    /* inherits from .course-card */
}

/* 课程卡片头标 80x80 */
.course-card__badge {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-2xl);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--text-3xl);
    font-weight: 700;
    color: #ffffff;
    box-shadow: var(--shadow-lg);
    margin-bottom: var(--spacing-md);
}

.course-card__badge--math {
    background: linear-gradient(135deg, var(--accent) 0%, var(--accent-dark) 100%);
}

.course-card__badge--physics {
    background: linear-gradient(135deg, #14b8a6 0%, #0f766e 100%);
}

.course-card__badge--code {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    font-family: var(--font-mono);
    font-size: var(--text-xl);
    letter-spacing: -0.04em;
}

/* 课程标签 (chip) */
.course-tag {
    padding: 4px 12px;
    border-radius: var(--radius-full);
    font-size: var(--text-xs);
    font-weight: 500;
}

.course-tag--math {
    background: var(--accent-soft);
    color: var(--accent-dark);
}

.course-tag--physics {
    background: #ccfbf1;
    color: #0f766e;
}

.course-tag--code {
    background: var(--primary-soft);
    color: var(--primary-dark);
}

.course-tag--neutral {
    background: rgba(15, 23, 42, 0.05);
    color: var(--text-secondary);
}

/* ===== 表单 ===== */
.form-group {
    margin-bottom: var(--spacing-md);
}

.form-label {
    display: block;
    font-size: var(--text-sm);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.form-label .required {
    color: var(--error);
}

.form-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    background: rgba(255, 255, 255, 0.8);
    border: 1px solid rgba(0, 0, 0, 0.15);
    color: var(--text-primary);
    font-size: var(--text-sm);
    font-family: inherit;
    transition: var(--transition-fast);
}

.form-input:focus,
.form-input:focus-visible {
    outline: none;
    border-color: var(--primary);
    box-shadow: var(--shadow-focus);
}

/* 链接焦点环 */
a:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 3px;
    border-radius: 2px;
}

/* nav 链接焦点态(避免双重焦点环) */
.nav-link:focus-visible,
.nav-mobile-link:focus-visible,
.nav-dropdown-item:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus);
    border-radius: var(--radius-md);
}

/* 汉堡按钮/模态关闭按钮焦点态 */
.nav-mobile-toggle:focus-visible,
.nav-mobile-menu-close:focus-visible,
.modal-close:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus);
}

.form-input::placeholder {
    color: rgba(100, 116, 139, 0.5);
}

.form-input:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.form-error {
    color: var(--error);
    font-size: var(--text-sm);
    margin-top: var(--spacing-xs);
}

.form-hint {
    color: var(--text-muted);
    font-size: var(--text-xs);
    margin-top: var(--spacing-xs);
}

/* Modal 样式见后文统一定义(行 ~1040 起) */

/* ===== 徽章 ===== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: var(--text-xs);
    font-weight: 500;
}

.badge-primary {
    background: rgba(var(--primary-rgb), 0.2);
    color: var(--primary-light);
}

.badge-secondary {
    background: rgba(var(--secondary-rgb), 0.2);
    color: var(--secondary-light);
}

.badge-success {
    background: rgba(16, 185, 129, 0.15);
    color: #059669;
}

.badge-warning {
    background: rgba(245, 158, 11, 0.15);
    color: #d97706;
}

.badge-error {
    background: rgba(239, 68, 68, 0.15);
    color: #dc2626;
}

.badge-neutral {
    background: rgba(100, 116, 139, 0.15);
    color: #475569;
}

/* ===== 进度环 ===== */
.progress-ring {
    transform: rotate(-90deg);
}

.progress-ring-circle {
    transition: stroke-dashoffset 0.5s ease;
}

/* ===== Toast 提示 ===== */
.toast-container {
    position: fixed;
    top: 80px;
    right: 20px;
    z-index: var(--z-toast);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.toast {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    animation: toastSlideIn 0.3s ease;
    max-width: 360px;
}

.toast.toast-success {
    border-color: var(--success);
    background: rgba(16, 185, 129, 0.1);
}

.toast.toast-error {
    border-color: var(--error);
    background: rgba(239, 68, 68, 0.1);
}

.toast.toast-warning {
    border-color: var(--warning);
    background: rgba(245, 158, 11, 0.1);
}

.toast.toast-info {
    border-color: var(--info);
    background: rgba(59, 130, 246, 0.1);
}

.toast-icon {
    flex-shrink: 0;
    width: 20px;
    height: 20px;
}

.toast-message {
    flex: 1;
    font-size: var(--text-sm);
}

.toast-close {
    flex-shrink: 0;
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 4px;
}

.toast.hiding {
    animation: toastSlideOut 0.3s ease forwards;
}

@keyframes toastSlideIn {
    from {
        opacity: 0;
        transform: translateX(100%);
    }

    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes toastSlideOut {
    from {
        opacity: 1;
        transform: translateX(0);
    }

    to {
        opacity: 0;
        transform: translateX(100%);
    }
}

/* ===== 骨架屏 ===== */
.skeleton {
    background: linear-gradient(90deg,
            rgba(0, 0, 0, 0.04) 0%,
            rgba(0, 0, 0, 0.08) 50%,
            rgba(0, 0, 0, 0.04) 100%);
    background-size: 200% 100%;
    animation: skeletonShimmer 1.5s ease-in-out infinite;
    border-radius: var(--radius-md);
}

@keyframes skeletonShimmer {
    0% {
        background-position: 200% 0;
    }

    100% {
        background-position: -200% 0;
    }
}

.skeleton-text {
    height: 1em;
    margin-bottom: 0.5em;
}

.skeleton-text:last-child {
    width: 60%;
}

.skeleton-avatar {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-lg);
}

.skeleton-card {
    height: 200px;
    border-radius: var(--radius-2xl);
}

/* ===== 品牌标语 ===== */
.brand-slogan {
    background: linear-gradient(90deg,
            rgba(var(--primary-rgb), 0.1) 0%,
            rgba(var(--secondary-rgb), 0.1) 50%,
            rgba(var(--accent-rgb), 0.1) 100%);
    border-left: 4px solid var(--primary);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
}

/* ===== 统计数字 ===== */
.stat-number {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
}

/* ===== Footer ===== */
.footer {
    background: linear-gradient(180deg, transparent 0%, rgba(241, 245, 249, 0.95) 100%);
    padding: var(--spacing-2xl) var(--spacing-lg);
}

.footer-container {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-lg);
}

@media (min-width: 768px) {
    .footer-container {
        flex-direction: row;
        justify-content: space-between;
    }
}

/* ===== 微交互效果 ===== */
.hover-lift {
    transition: transform var(--transition-bounce), box-shadow var(--transition-bounce);
}

.hover-lift:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.hover-scale {
    transition: transform var(--transition-fast);
}

.hover-scale:hover {
    transform: scale(1.02);
}

.hover-glow {
    transition: box-shadow var(--transition-normal);
}

.hover-glow:hover {
    box-shadow: 0 0 20px rgba(var(--primary-rgb), 0.3);
}

/* 点击反馈 */
.click-feedback {
    transition: transform var(--transition-fast);
}

.click-feedback:active {
    transform: scale(0.97);
}

/* 焦点环 */
.focus-ring:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgba(var(--primary-rgb), 0.3);
}

.focus-ring:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* ===== 加载状态 ===== */
.loading-spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-default);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.loading-spinner--sm {
    width: 20px;
    height: 20px;
    border-width: 2px;
}

.loading-spinner--lg {
    width: 56px;
    height: 56px;
    border-width: 4px;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* 按钮加载状态 */
.btn--loading {
    position: relative;
    color: transparent !important;
    pointer-events: none;
}

.btn--loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

/* 页面加载骨架 */
.page-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 60vh;
    gap: var(--spacing-md);
}

.page-loading-text {
    color: var(--text-secondary);
    font-size: var(--text-sm);
}

/* 内容加载占位 */
.content-placeholder {
    background: var(--bg-glass);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-lg);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {

    0%,
    100% {
        opacity: 1;
    }

    50% {
        opacity: 0.6;
    }
}

/* ===== 编程链接按钮组 ===== */
.code-links {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.code-link {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 12px;
    font-size: var(--text-sm);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-default);
    background: rgba(0, 0, 0, 0.02);
    color: var(--text-secondary);
    transition: var(--transition-fast);
}

.code-link:hover {
    border-color: var(--primary);
    background: rgba(var(--primary-rgb), 0.1);
    color: var(--primary);
}

.code-link--cpp {
    border-color: rgba(16, 185, 129, 0.3);
}

.code-link--cpp:hover {
    border-color: var(--primary);
    background: rgba(var(--primary-rgb), 0.1);
}

.code-link--python {
    border-color: rgba(59, 130, 246, 0.3);
}

.code-link--python:hover {
    border-color: var(--secondary);
    background: rgba(var(--secondary-rgb), 0.1);
}

.code-link svg {
    width: 16px;
    height: 16px;
}

/* ===== 优化的模态框 ===== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.4);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    z-index: var(--z-modal);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-md);
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-normal), visibility var(--transition-normal);
}

.modal-overlay.open {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--bg-secondary);
    border: 1px solid var(--border-default);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    width: 100%;
    max-width: 440px;
    max-height: 90vh;
    overflow-y: auto;
    transform: translateY(20px) scale(0.95);
    opacity: 0;
    transition: transform var(--transition-normal), opacity var(--transition-normal);
}

.modal-overlay.open .modal {
    transform: translateY(0) scale(1);
    opacity: 1;
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
}

.modal-title {
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
}

.modal-close {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.04);
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: var(--transition-fast);
    font-size: 1.25rem;
}

.modal-close:hover {
    background: rgba(0, 0, 0, 0.06);
    color: var(--text-primary);
}

/* 模态框内的标签切换 */
.modal-tabs {
    display: flex;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-lg);
    padding: 4px;
    background: rgba(0, 0, 0, 0.03);
    border-radius: var(--radius-lg);
}

.modal-tab {
    flex: 1;
    padding: var(--spacing-sm) var(--spacing-md);
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: var(--text-sm);
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition-fast);
}

.modal-tab:hover {
    color: var(--text-primary);
}

.modal-tab.active {
    background: rgba(var(--primary-rgb), 0.15);
    color: var(--primary);
}

/* ===== 响应式容器 ===== */
.section {
    padding: var(--section-padding-y) var(--container-padding-x);
}

@media (max-width: 768px) {
    .section {
        padding: var(--section-padding-y-mobile) var(--container-padding-x-mobile);
    }
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-12);
}

.section-title {
    font-size: var(--text-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    font-size: var(--text-base);
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

@media (max-width: 768px) {
    .section-title {
        font-size: var(--text-2xl);
    }

    .section-subtitle {
        font-size: var(--text-sm);
    }
}

/* ===== 移动端响应式改进 ===== */
@media (max-width: 640px) {
    .card {
        padding: var(--spacing-md);
    }

    .feature-card {
        padding: var(--spacing-md);
    }

    .course-card {
        padding: var(--spacing-lg);
    }

    .modal {
        padding: var(--spacing-lg);
        max-width: 100%;
        margin: var(--spacing-md);
        border-radius: var(--radius-xl);
    }

    .btn-xl {
        padding: 0.875rem 1.5rem;
        font-size: var(--text-base);
    }
}
/* =========================================
   登录/注册弹窗 (Auth Modal)
   说明:用 .auth-modal 作为命名空间提升特异性,
        不再依赖 body 前缀和 !important
   ========================================= */

.auth-modal {
    background: #ffffff;
    backdrop-filter: blur(24px) saturate(180%);
    -webkit-backdrop-filter: blur(24px) saturate(180%);
    border: 1px solid var(--border-default);
    box-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.18);
    border-radius: 24px;
    overflow: hidden;
    max-width: 900px;
}

.auth-modal .auth-modal__layout {
    grid-template-columns: 280px 1fr;
}

.auth-modal .auth-modal__aside {
    background: linear-gradient(160deg,
        #fafbfc 0%,
        #f4f5f7 60%,
        rgba(var(--primary-rgb), 0.04) 100%);
    border-right: 1px solid var(--border-light);
    position: relative;
    overflow: hidden;
}

.auth-modal .auth-modal__aside::before {
    content: '';
    position: absolute;
    bottom: -120px;
    right: -120px;
    width: 280px;
    height: 280px;
    background: radial-gradient(circle,
        rgba(var(--primary-rgb), 0.06) 0%, transparent 65%);
    pointer-events: none;
}

/* 输入框 */
.auth-modal .input-group input {
    background: rgba(255, 255, 255, 0.85);
    border: 1px solid var(--border-default);
    border-radius: 12px;
    color: var(--text-primary);
    padding: 14px 16px;
    font-size: 15px;
    transition: var(--transition-bounce);
}

.auth-modal .input-group input:hover {
    background: rgba(255, 255, 255, 0.96);
    border-color: var(--border-strong);
}

.auth-modal .input-group input:focus {
    background: #ffffff;
    border-color: var(--primary);
    box-shadow: var(--shadow-focus);
    outline: none;
}

/* 验证码 - 容器尺寸由内部 .slider-captcha-canvas (280×155) / .captcha-image (120×40) 决定 */

/* Tab 胶囊 */
.auth-modal .auth-tabs {
    background: rgba(15, 23, 42, 0.04);
    padding: 4px;
    border-radius: 50px;
    border: 1px solid var(--border-light);
    display: inline-flex;
    width: 100%;
}

.auth-modal .auth-tab {
    flex: 1;
    border-radius: 40px;
    padding: 10px 0;
    color: var(--text-muted);
    transition: var(--transition-fast);
    border-bottom: none;
    position: relative;
    z-index: 1;
    cursor: pointer;
    background: transparent;
    border: none;
    font-size: var(--text-sm);
}

.auth-modal .auth-tab.active {
    background: linear-gradient(135deg,
        rgba(var(--primary-rgb), 0.18),
        rgba(var(--primary-rgb), 0.09));
    color: var(--primary-dark);
    box-shadow: 0 4px 12px rgba(15, 23, 42, 0.08);
    font-weight: 600;
}

/* 主按钮(绿色品牌色) */
.auth-modal .btn-auth-submit {
    background: linear-gradient(135deg,
        var(--primary) 0%, var(--primary-dark) 100%);
    color: #ffffff;
    border: none;
    border-radius: 12px;
    padding: 14px;
    font-size: 16px;
    font-weight: 600;
    letter-spacing: 0.3px;
    cursor: pointer;
    width: 100%;
    box-shadow:
        var(--shadow-primary),
        0 0 0 1px rgba(255, 255, 255, 0.18) inset;
    transition: transform 0.2s, box-shadow 0.2s;
    position: relative;
    overflow: hidden;
}

.auth-modal .btn-auth-submit::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg,
        transparent, rgba(255, 255, 255, 0.22), transparent);
    transition: 0.6s;
}

.auth-modal .btn-auth-submit:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 24px -6px rgba(var(--primary-rgb), 0.45);
}

.auth-modal .btn-auth-submit:hover::after { left: 100%; }

.auth-modal .btn-auth-submit:focus-visible {
    outline: none;
    box-shadow: var(--shadow-focus), var(--shadow-primary);
}

/* 标题 */
.auth-modal .auth-title {
    font-size: 24px;
    font-weight: 700;
    letter-spacing: -0.01em;
    margin-bottom: 24px;
    color: var(--text-primary);
}

/* 移动端:底部抽屉 */
@media (max-width: 768px) {
    .auth-modal {
        max-width: 100vw;
        margin: 0;
        border-radius: 24px 24px 0 0;
        position: fixed;
        bottom: 0;
        left: 0;
        right: 0;
        top: auto;
        transform: translateY(100%);
        border: none;
        border-top: 1px solid var(--border-default);
        box-shadow: 0 -10px 40px rgba(15, 23, 42, 0.18);
        max-height: 85vh;
        overflow-y: auto;
    }

    .modal-overlay.open .auth-modal {
        transform: translateY(0);
    }

    .auth-modal .auth-modal__aside { display: none; }
    .auth-modal .auth-modal__layout { display: block; }
    .auth-modal .auth-modal__content { padding: 32px 24px; }

    .auth-modal .auth-header {
        text-align: center;
        margin-bottom: 24px;
        position: relative;
    }

    .auth-modal .auth-header::before {
        content: '';
        display: block;
        width: 48px;
        height: 48px;
        background-image: url('/static/logo-icon.png?v=3');
        background-size: contain;
        background-repeat: no-repeat;
        margin: 0 auto 16px auto;
        filter: drop-shadow(0 0 10px rgba(var(--primary-rgb), 0.45));
    }
}