/* Pippo Studio - Main Stylesheet */
/* ================================ */

/* CSS Variables */
:root {
    /* Dark Theme Colors */
    --primary-dark: #1a1d23;
    --secondary-dark: #242831;
    --tertiary-dark: #2d323d;
    
    /* Light Colors */
    --soft-white: #f5f6fa;
    --warm-white: #e8eaed;
    --pure-white: #ffffff;
    
    /* Accent Colors */
    --accent-rose: #e8b4a0;
    --accent-gold: #c9a96e;
    --accent-purple: #8b7cb6;
    
    /* Brand Colors */
    --primary-blue: #007aff;
    --soft-blue: #5ac8fa;
    --ocean-blue: #4fc3f7;
    --ocean-dark: #0288d1;
    
    /* Text Colors - 阶段1: 增强对比度 */
    --text-primary: #f8f9fa; /* 提升亮度 */
    --text-secondary: #c8cad3; /* 提升对比度 */
    --text-muted: #9a9aa3; /* 稍微提亮 */
    --text-disabled: #6c6c7d;
    
    /* UI Colors */
    --warm-gray: #8e8e93;
    --light-gray: #c7c7cc;
    --medium-gray: #6c6c7d;
    
    /* Status Colors */
    --steam-blue: #4a6741;
    --success-green: #7cb342;
    --warning-yellow: #ffa726;
    --error-red: #ef5350;
    
    /* Effects */
    --glass-bg: rgba(255, 255, 255, 0.05);
    --glass-border: rgba(255, 255, 255, 0.1);
    --glass-hover: rgba(255, 255, 255, 0.08);
    --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 10px 40px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.4);
    
    /* 改进的间距系统 - 基于 1.5 比例 */
    --spacing-xs: 0.375rem;   /* 6px */
    --spacing-sm: 0.75rem;    /* 12px */
    --spacing-md: 1.125rem;   /* 18px */
    --spacing-lg: 1.75rem;    /* 28px */
    --spacing-xl: 2.625rem;   /* 42px */
    --spacing-2xl: 4rem;      /* 64px */
    --spacing-3xl: 6rem;      /* 96px */
    --spacing-4xl: 8rem;      /* 128px */
    
    /* 响应式间距 */
    --section-spacing: clamp(var(--spacing-xl), 8vw, var(--spacing-4xl));
    --element-spacing: clamp(var(--spacing-md), 3vw, var(--spacing-xl));
    --micro-spacing: clamp(var(--spacing-xs), 1vw, var(--spacing-sm));
    
    /* Typography */
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-display: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', monospace;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-normal: 300ms ease;
    --transition-slow: 500ms ease;
    
    /* Breakpoints */
    --mobile: 480px;
    --tablet: 768px;
    --desktop: 1024px;
    --wide: 1440px;
    
    /* Z-index layers */
    --z-base: 1;
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-overlay: 300;
    --z-modal: 400;
    --z-tooltip: 500;
    
    /* 改进的设计代币系统 */
    /* 圆角系统 */
    --radius-xs: 4px;
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-2xl: 24px;
    --radius-full: 9999px;
    
    /* 阴影系统 */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 8px 16px rgba(0, 0, 0, 0.15);
    --shadow-lg: 0 16px 32px rgba(0, 0, 0, 0.2);
    --shadow-xl: 0 24px 48px rgba(0, 0, 0, 0.25);
    --shadow-2xl: 0 32px 64px rgba(0, 0, 0, 0.3);
    
    /* 动效曲线 */
    --ease-linear: linear;
    --ease-in: cubic-bezier(0.4, 0, 1, 1);
    --ease-out: cubic-bezier(0, 0, 0.2, 1);
    --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-bounce: cubic-bezier(0.68, -0.55, 0.265, 1.55);
    --ease-elastic: cubic-bezier(0.25, 0.46, 0.45, 0.94);
    
    /* 渐变系统 */
    --gradient-primary: linear-gradient(135deg, var(--primary-blue), var(--soft-blue));
    --gradient-accent: linear-gradient(135deg, var(--accent-rose), var(--accent-gold));
    --gradient-glass: linear-gradient(135deg, 
        rgba(255, 255, 255, 0.1), 
        rgba(255, 255, 255, 0.05)
    );
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-main);
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--secondary-dark) 100%);
    color: var(--text-primary);
    line-height: 1.7; /* 阶段1: 优化行高，提升可读性 */
    min-height: 100vh;
    font-weight: 400;
    letter-spacing: 0.01em;
    /* 阶段1: 优化文字渲染 */
    text-rendering: optimizeLegibility;
    -webkit-font-feature-settings: "kern" 1;
    font-feature-settings: "kern" 1;
    
    /* 加载动画 */
    animation: fadeIn 0.5s ease-out;
    
    /* 文本渲染优化 */
    text-rendering: optimizeLegibility;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 阶段2: 改进的焦点样式 */
:focus {
    outline: 2px solid var(--primary-blue);
    outline-offset: 2px;
}

:focus:not(:focus-visible) {
    outline: none;
}

:focus-visible {
    outline: 2px solid var(--primary-blue);
    outline-offset: 3px;
    border-radius: 4px;
    /* 阶段2: 添加焦点光晕 */
    box-shadow: 0 0 0 4px rgba(0, 122, 255, 0.1);
}

/* Skip to main content link */
.skip-to-main {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--primary-blue);
    color: white;
    padding: var(--spacing-sm) var(--spacing-md);
    text-decoration: none;
    z-index: var(--z-tooltip);
    border-radius: 0 0 8px 0;
}

.skip-to-main:focus {
    top: 0;
}

/* Typography - 阶段1: 优化标题层次 */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-display);
    font-weight: 600;
    letter-spacing: -0.02em;
    line-height: 1.2;
    color: var(--text-primary);
    /* 阶段1: 添加标题间距 */
    margin-top: 0;
    margin-bottom: var(--spacing-md);
}

/* 阶段1: 渐进式字重 */
h1 { font-weight: 700; } /* 更强的主标题 */
h2 { font-weight: 600; }
h3 { font-weight: 600; }
h4, h5, h6 { font-weight: 500; }

/* 改进的字体层次系统 */
h1 { 
    font-size: clamp(2.5rem, 6vw, 4rem); 
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 1.5rem;
}
h2 { 
    font-size: clamp(1.75rem, 4.5vw, 2.75rem); 
    font-weight: 600;
    margin-bottom: 1.25rem;
    color: var(--text-primary);
}
h3 { 
    font-size: clamp(1.35rem, 3.5vw, 2.2rem); 
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}
h4 { 
    font-size: clamp(1.15rem, 2.8vw, 1.65rem); 
    font-weight: 500;
    margin-bottom: 0.75rem;
    color: var(--text-secondary);
}

p {
    margin-bottom: var(--spacing-lg); /* 阶段1: 增加段落间距 */
    color: var(--text-secondary);
    font-size: clamp(0.95rem, 2vw, 1.1rem);
    /* 阶段1: 限制段落最大宽度，提升可读性 */
    max-width: 65ch; /* 最佳阅读宽度约65字符 */
    line-height: 1.75; /* 段落专用行高 */
}

a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: color var(--transition-normal);
    /* 阶段2: 添加下划线动画准备 */
    position: relative;
}

/* 阶段2: 优雅的悬停下划线效果 */
a:hover {
    color: var(--soft-blue);
}

/* 阶段2: 为段落中的链接添加下划线动画 */
p a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 1px;
    background-color: var(--soft-blue);
    transition: width 0.3s ease;
}

p a:hover::after {
    width: 100%;
}

/* Navigation Styles */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(26, 29, 35, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    z-index: var(--z-sticky);
    border-bottom: 1px solid var(--glass-border);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-md) var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    transition: all var(--transition-normal);
}

.logo:hover {
    color: var(--primary-blue);
    transform: translateX(5px);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
    align-items: center;
}

.nav-menu a {
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: 8px;
    transition: all var(--transition-normal);
    position: relative;
}

/* 阶段2: 改进导航悬停效果 */
.nav-menu a::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--primary-blue);
    transform: translateX(-50%);
    transition: width 0.3s ease;
}

.nav-menu a:hover,
.nav-menu a:focus {
    color: var(--text-primary);
    background: var(--glass-bg);
}

.nav-menu a:hover::before {
    width: calc(100% - 2rem);
}

.nav-menu a.active {
    color: var(--primary-blue);
}

/* Unified Language Selector */
.language-selector {
    display: flex;
    gap: var(--spacing-xs);
    padding: 4px;
    background: var(--glass-bg);
    border-radius: 12px;
    border: 1px solid var(--glass-border);
}

.lang-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    background: transparent;
    border: none;
    color: var(--text-secondary);
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    min-width: 60px;
}

.lang-btn:hover {
    background: var(--glass-hover);
    color: var(--text-primary);
}

.lang-btn.active {
    background: var(--primary-blue);
    color: white;
}

/* Loading States */
.loading {
    position: relative;
    pointer-events: none;
    opacity: 0.6;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid var(--primary-blue);
    border-radius: 50%;
    border-top-color: transparent;
    animation: spin 0.8s linear infinite;
}

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

/* Loading Skeleton */
.skeleton {
    background: linear-gradient(
        90deg,
        var(--glass-bg) 25%,
        var(--glass-hover) 50%,
        var(--glass-bg) 75%
    );
    background-size: 200% 100%;
    animation: loading 1.5s infinite;
}

@keyframes loading {
    0% { background-position: 200% 0; }
    100% { background-position: -200% 0; }
}

/* 改进的按钮系统 */
/* 阶段2: 改进的按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--primary-blue);
    color: white;
    border: none;
    border-radius: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-normal);
    text-decoration: none;
    font-size: 1rem;
    position: relative;
    /* 阶段2: 添加细微阴影增加层次感 */
    box-shadow: 0 2px 8px rgba(0, 122, 255, 0.2);
    /* 阶段2: 防止文字选中 */
    user-select: none;
    -webkit-user-select: none;
    overflow: hidden;
    min-height: 48px; /* 触摸友好尺寸 */
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, 
        transparent, 
        rgba(255, 255, 255, 0.2), 
        transparent
    );
    transition: left var(--transition-slow);
}

.btn:hover::before {
    left: 100%;
}

/* 阶段2: 增强的悬停效果 */
.btn:hover {
    background: var(--soft-blue);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 122, 255, 0.3);
}

/* 阶段2: 改进的点击反馈 */
.btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 8px rgba(0, 122, 255, 0.2);
    transition-duration: 0.05s;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.btn:disabled:hover {
    transform: none;
    box-shadow: none;
}

.btn-secondary {
    background: var(--glass-bg);
    border: 2px solid var(--glass-border);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--glass-hover);
    border-color: var(--primary-blue);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary-blue);
    color: var(--primary-blue);
}

.btn-outline:hover {
    background: var(--primary-blue);
    color: white;
    box-shadow: 0 8px 16px rgba(0, 122, 255, 0.25);
}

/* 改进的卡片系统 */
/* 阶段3: 优化的卡片间距和布局 */
.card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: var(--radius-xl); /* 使用统一的圆角系统 */
    padding: var(--spacing-xl); /* 阶段3: 保持xl间距 */
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
    height: 100%; /* 确保等高对齐 */
    display: flex;
    flex-direction: column;
    /* 阶段3: 增强的阴影层次 */
    box-shadow: 
        0 1px 3px rgba(0, 0, 0, 0.05),
        0 4px 6px rgba(0, 0, 0, 0.02);
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, 
        transparent, 
        var(--primary-blue) 50%, 
        transparent
    );
    opacity: 0;
    transition: opacity var(--transition-normal);
}

/* 阶段3: 增强的卡片悬停效果 */
.card:hover {
    background: var(--glass-hover);
    transform: translateY(-6px) scale(1.01); /* 阶段3: 添加细微缩放 */
    box-shadow: 
        0 8px 16px rgba(0, 0, 0, 0.1),
        0 20px 40px rgba(0, 0, 0, 0.08); /* 阶段3: 双层阴影 */
    border-color: rgba(255, 255, 255, 0.15);
}

.card:hover::before {
    opacity: 1;
}

.card-header {
    margin-bottom: var(--spacing-lg);
}

.card-body {
    flex: 1;
    /* 阶段3: 优化内容间距 */
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.card-footer {
    margin-top: var(--spacing-xl); /* 阶段3: 增加footer间距 */
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

/* Mobile Menu Toggle */
.mobile-menu-toggle {
    display: none;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
    padding: var(--spacing-sm);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--secondary-dark);
        flex-direction: column;
        padding: var(--spacing-md);
        gap: var(--spacing-sm);
        border-bottom: 1px solid var(--glass-border);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .language-selector {
        margin-top: var(--spacing-md);
    }
}

/* 改进的动画系统 */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-40px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(40px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

@keyframes shimmer {
    0% {
        background-position: -200% 0;
    }
    100% {
        background-position: 200% 0;
    }
}

/* 动画应用类 */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.animate-on-scroll.animate-in {
    opacity: 1;
    transform: translateY(0);
}

.animate-delay-1 { transition-delay: 0.1s; }
.animate-delay-2 { transition-delay: 0.2s; }
.animate-delay-3 { transition-delay: 0.3s; }
.animate-delay-4 { transition-delay: 0.4s; }

/* 页面加载动画 */
.page-transition {
    animation: fadeInUp 0.6s ease-out;
}

.card-stagger:nth-child(1) { animation-delay: 0.1s; }
.card-stagger:nth-child(2) { animation-delay: 0.2s; }
.card-stagger:nth-child(3) { animation-delay: 0.3s; }
.card-stagger:nth-child(4) { animation-delay: 0.4s; }

/* Utility Classes */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--element-spacing);
}

/* 阶段1: 文字可读性优化类 */
.readable-width {
    max-width: 65ch;
    margin-left: auto;
    margin-right: auto;
}

.text-balance {
    text-wrap: balance; /* 优化标题换行 */
}

/* 阶段1: 优化链接的可读性 */
a:focus-visible {
    outline: 2px solid var(--primary-blue);
    outline-offset: 3px;
    border-radius: 2px;
}

/* 阶段2: 交互反馈工具类 */
.interactive {
    transition: all var(--transition-normal);
    cursor: pointer;
}

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

.interactive:active {
    transform: scale(0.98);
}

/* 阶段2: 禁用状态样式 */
.disabled,
[disabled] {
    opacity: 0.6;
    cursor: not-allowed;
    pointer-events: none;
}

/* 改进的容器系统 */
.container-narrow {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--element-spacing);
}

.container-wide {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--element-spacing);
}

.container-fluid {
    width: 100%;
    padding: 0 var(--element-spacing);
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.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;
}

/* 统一的状态指示器系统 */
.status-indicator {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-full);
    font-size: 0.85rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.status-success {
    background: rgba(124, 179, 66, 0.1);
    color: var(--success-green);
    border: 1px solid rgba(124, 179, 66, 0.2);
}

.status-warning {
    background: rgba(255, 167, 38, 0.1);
    color: var(--warning-yellow);
    border: 1px solid rgba(255, 167, 38, 0.2);
}

.status-error {
    background: rgba(239, 83, 80, 0.1);
    color: var(--error-red);
    border: 1px solid rgba(239, 83, 80, 0.2);
}

.status-info {
    background: rgba(0, 122, 255, 0.1);
    color: var(--primary-blue);
    border: 1px solid rgba(0, 122, 255, 0.2);
}

/* 改进的加载状态 */
.loading-language {
    transition: opacity var(--transition-normal);
}

.loading-language * {
    pointer-events: none;
}

/* 高对比度模式支持 */
@media (prefers-contrast: high) {
    :root {
        --glass-bg: rgba(255, 255, 255, 0.1);
        --glass-border: rgba(255, 255, 255, 0.3);
        --text-secondary: #ffffff;
    }
    
    .card {
        border-width: 2px;
    }
    
    .btn {
        border: 2px solid transparent;
    }
    
    .btn:focus {
        border-color: currentColor;
    }
}

/* 响应式图片系统 */
.responsive-image {
    width: 100%;
    height: auto;
    border-radius: var(--radius-lg);
    transition: all var(--transition-normal);
}

.responsive-image:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-lg);
}

.image-placeholder {
    background: var(--gradient-glass);
    border: 2px dashed var(--glass-border);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    color: var(--text-muted);
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* 阶段3: 增强的内容分组和视觉层次 */
.content-section {
    margin: var(--section-spacing) 0; /* 阶段3: 使用响应式间距 */
    padding: var(--spacing-2xl) 0;
    position: relative;
}

.content-section + .content-section {
    border-top: 1px solid rgba(255, 255, 255, 0.08);
    padding-top: var(--section-spacing); /* 阶段3: 增加分隔后的顶部间距 */
}

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

.section-title {
    position: relative;
    display: inline-block;
    margin-bottom: var(--spacing-md);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary-blue), var(--soft-blue));
    border-radius: 2px;
}

.section-subtitle {
    font-size: clamp(1rem, 2.5vw, 1.25rem);
    color: var(--text-muted);
    font-weight: 400;
    max-width: 60ch;
    margin: 0 auto;
}

/* 阶段3: 优化的内容网格系统 */
.content-grid {
    display: grid;
    gap: var(--spacing-xl); /* 阶段3: 保持xl间距 */
    margin-top: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

/* 阶段3: 响应式网格，避免卡片过小 */
.content-grid.two-col {
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 400px), 1fr));
}

.content-grid.three-col {
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 320px), 1fr));
}

.content-grid.four-col {
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 280px), 1fr));
}

/* 阶段3: 桌面端增加间距 */
@media (min-width: 1024px) {
    .content-grid {
        gap: var(--spacing-2xl);
    }
}

/* Print Styles */
@media print {
    nav, .language-selector, .mobile-menu-toggle {
        display: none;
    }
    
    body {
        background: white;
        color: black;
    }
}