/* ========================================
   GitHub 个人主页 - 样式表
   ======================================== */

/* CSS 变量 */
:root {
    /* 颜色 */
    --primary: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --secondary: #f472b6;
    --accent: #22d3ee;
    --success: #34d399;
    --warning: #fbbf24;
    --danger: #f87171;

    /* 背景 */
    --bg-body: #0f172a;
    --bg-card: rgba(30, 41, 59, 0.6);
    --bg-card-hover: rgba(30, 41, 59, 0.8);
    --bg-nav: rgba(15, 23, 42, 0.85);
    --bg-input: rgba(30, 41, 59, 0.5);

    /* 文字 */
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;
    --text-inverse: #0f172a;

    /* 边框 */
    --border-color: rgba(148, 163, 184, 0.15);
    --border-radius: 12px;
    --border-radius-sm: 8px;
    --border-radius-lg: 16px;

    /* 间距 */
    --section-padding: 100px;
    --container-max-width: 1200px;

    /* 动画 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* 阴影 */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);

    /* 字体 */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
}

/* 浅色主题 */
[data-theme="light"] {
    --bg-body: #f8fafc;
    --bg-card: rgba(255, 255, 255, 0.7);
    --bg-card-hover: rgba(255, 255, 255, 0.9);
    --bg-nav: rgba(248, 250, 252, 0.85);
    --bg-input: rgba(255, 255, 255, 0.5);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --text-inverse: #f8fafc;
    --border-color: rgba(148, 163, 184, 0.2);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.15);
}

/* 重置样式 */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-body);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

a {
    color: inherit;
    text-decoration: none;
}

ul {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

/* 加载动画 */
.loader {
    position: fixed;
    inset: 0;
    background: var(--bg-body);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 9999;
    transition: opacity 0.5s ease, visibility 0.5s ease;
}

.loader.hidden {
    opacity: 0;
    visibility: hidden;
}

.loader-spinner {
    width: 50px;
    height: 50px;
    border: 3px solid var(--border-color);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

.loader-text {
    margin-top: 1rem;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.loader-text span {
    animation: fadeInOut 1.4s infinite;
}

.loader-text span:nth-child(2) { animation-delay: 0.2s; }
.loader-text span:nth-child(3) { animation-delay: 0.4s; }

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

@keyframes fadeInOut {
    0%, 100% { opacity: 0; }
    50% { opacity: 1; }
}

/* 粒子背景 */
#particle-canvas {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    pointer-events: none;
}

/* ========================================
   导航栏
   ======================================== */

.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 1rem 0;
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    background: var(--bg-nav);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: var(--shadow-md);
    padding: 0.75rem 0;
}

.nav-container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-logo i {
    font-size: 1.5rem;
    color: var(--primary);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.nav-link {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: var(--border-radius-sm);
    transition: all var(--transition-fast);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary);
    background: rgba(99, 102, 241, 0.1);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.theme-toggle {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    color: var(--text-secondary);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    font-size: 1rem;
}

.theme-toggle:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.mobile-menu-toggle {
    display: none;
    width: 40px;
    height: 40px;
    border: none;
    background: none;
    cursor: pointer;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    padding: 8px;
}

.mobile-menu-toggle span {
    display: block;
    width: 100%;
    height: 2px;
    background: var(--text-primary);
    border-radius: 2px;
    transition: all var(--transition-fast);
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* ========================================
   英雄区域
   ======================================== */

.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 6rem 2rem 4rem;
    position: relative;
}

.hero-content {
    max-width: 800px;
    animation: fadeInUp 1s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-avatar {
    position: relative;
    display: inline-block;
    margin-bottom: 2rem;
}

.avatar-wrapper {
    position: relative;
    width: 160px;
    height: 160px;
    margin: 0 auto;
}

.avatar-img {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--primary);
    position: relative;
    z-index: 2;
}

.avatar-ring {
    position: absolute;
    inset: -8px;
    border-radius: 50%;
    border: 2px dashed var(--primary-light);
    animation: rotateRing 20s linear infinite;
}

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

.status-indicator {
    position: absolute;
    bottom: 10px;
    right: 10px;
    z-index: 3;
    width: 24px;
    height: 24px;
    background: var(--bg-body);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.status-dot {
    width: 14px;
    height: 14px;
    background: var(--success);
    border-radius: 50%;
    animation: pulse 2s ease infinite;
}

@keyframes pulse {
    0%, 100% { box-shadow: 0 0 0 0 rgba(52, 211, 153, 0.4); }
    50% { box-shadow: 0 0 0 8px rgba(52, 211, 153, 0); }
}

.hero-title {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary), var(--accent), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    background-size: 200% 200%;
    animation: gradientShift 5s ease infinite;
}

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

.hero-subtitle {
    font-size: clamp(1.25rem, 2.5vw, 1.75rem);
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    font-family: var(--font-mono);
    min-height: 2.5rem;
}

.typing-cursor {
    color: var(--primary);
    animation: blink 1s step-end infinite;
}

@keyframes blink {
    50% { opacity: 0; }
}

.hero-desc {
    font-size: 1.125rem;
    color: var(--text-muted);
    margin-bottom: 2.5rem;
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 2.5rem;
}

.hero-social {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.social-link {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.125rem;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

.social-link:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-muted);
    font-size: 0.75rem;
    animation: bounce 2s ease infinite;
}

.scroll-mouse {
    width: 22px;
    height: 36px;
    border: 2px solid var(--text-muted);
    border-radius: 11px;
    position: relative;
}

.scroll-wheel {
    width: 4px;
    height: 8px;
    background: var(--text-muted);
    border-radius: 2px;
    position: absolute;
    top: 6px;
    left: 50%;
    transform: translateX(-50%);
    animation: scrollWheel 2s ease infinite;
}

@keyframes scrollWheel {
    0%, 100% { top: 6px; opacity: 1; }
    50% { top: 18px; opacity: 0; }
}

@keyframes bounce {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(10px); }
}

/* ========================================
   按钮
   ======================================== */

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    font-size: 0.9375rem;
    font-weight: 600;
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
    cursor: pointer;
    border: none;
    font-family: inherit;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    color: white;
    box-shadow: 0 4px 14px rgba(99, 102, 241, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
    background: var(--bg-card);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-card-hover);
    border-color: var(--primary);
    transform: translateY(-2px);
}

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

.btn-outline:hover {
    border-color: var(--primary);
    color: var(--primary);
    transform: translateY(-2px);
}

.btn-full {
    width: 100%;
    justify-content: center;
}

/* ========================================
   通用区域样式
   ======================================== */

.section {
    padding: var(--section-padding) 0;
}

.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-tag {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--primary);
    letter-spacing: 0.2em;
    margin-bottom: 0.75rem;
}

.section-title {
    font-size: clamp(2rem, 4vw, 2.75rem);
    font-weight: 800;
    margin-bottom: 1rem;
}

.section-line {
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 2px;
    margin: 0 auto;
}

/* ========================================
   关于区域
   ======================================== */

.about-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.about-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    text-align: center;
    transition: all var(--transition-normal);
    backdrop-filter: blur(8px);
}

.about-card:hover {
    transform: translateY(-8px);
    border-color: var(--primary);
    box-shadow: var(--shadow-lg);
    background: var(--bg-card-hover);
}

.about-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--border-radius);
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    font-size: 1.5rem;
    color: white;
}

.about-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.about-card p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

/* ========================================
   技能区域
   ======================================== */

.skills-content {
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

.skill-category-title {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 1.25rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-primary);
}

.skill-category-title i {
    color: var(--primary);
    font-size: 1.25rem;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.skill-tag {
    display: inline-flex;
    align-items: center;
    padding: 0.625rem 1.25rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 100px;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
    cursor: default;
    position: relative;
    overflow: hidden;
}

.skill-tag::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 0 0 100px 100px;
    transition: width 0.6s ease;
    width: 0;
}

.skill-tag:hover {
    color: var(--text-primary);
    border-color: var(--primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.skill-tag:hover::before {
    width: 100%;
}

/* ========================================
   项目区域
   ======================================== */

.projects-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    transition: all var(--transition-normal);
    backdrop-filter: blur(8px);
}

.project-card:hover {
    transform: translateY(-8px);
    border-color: var(--primary);
    box-shadow: var(--shadow-lg);
}

.project-image {
    position: relative;
    height: 220px;
    overflow: hidden;
}

.project-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    color: white;
    opacity: 0.9;
}

.project-overlay {
    position: absolute;
    inset: 0;
    background: rgba(15, 23, 42, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.project-card:hover .project-overlay {
    opacity: 1;
}

.project-links {
    display: flex;
    gap: 1rem;
}

.project-link {
    background: transparent;
    color: white;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    opacity: 0;
    transition: opacity var(--transition-normal);
    pointer-events: none;
}

.project-card:hover .project-link {
    opacity: 1;
}

.project-link:hover {
    color: var(--primary-light);
}

.project-info {
    padding: 1.5rem;
}

.project-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
}

.project-desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1.25rem;
    line-height: 1.7;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.25rem;
}

.tech-tag {
    padding: 0.25rem 0.75rem;
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-light);
    border-radius: 100px;
    font-size: 0.75rem;
    font-weight: 600;
    font-family: var(--font-mono);
}

.project-stats {
    display: flex;
    gap: 1.25rem;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.project-stats span {
    display: flex;
    align-items: center;
    gap: 0.375rem;
}

.project-stats i {
    font-size: 0.75rem;
}

.projects-more {
    text-align: center;
}

/* ========================================
   统计区域
   ======================================== */

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    text-align: center;
    transition: all var(--transition-normal);
    backdrop-filter: blur(8px);
}

.stat-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary);
}

.stat-icon {
    width: 50px;
    height: 50px;
    border-radius: var(--border-radius);
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
    font-size: 1.25rem;
    color: white;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-family: var(--font-mono);
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
}

.stats-charts {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.chart-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 1.5rem;
    overflow: hidden;
    transition: all var(--transition-normal);
}

.chart-card:hover {
    border-color: var(--primary);
}

.chart-card img {
    width: 100%;
    height: auto;
    border-radius: var(--border-radius-sm);
}

.chart-card.full-width {
    grid-column: 1 / -1;
}

.stats-extra {
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

/* ========================================
   联系区域
   ======================================== */

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: start;
}

.contact-info h3 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.contact-info > p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.7;
}

.contact-items {
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.contact-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--border-radius);
    background: linear-gradient(135deg, var(--primary), var(--primary-dark));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.125rem;
    flex-shrink: 0;
}

.contact-detail {
    display: flex;
    flex-direction: column;
}

.contact-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
    margin-bottom: 0.25rem;
}

.contact-detail a,
.contact-detail span:last-child {
    color: var(--text-primary);
    font-weight: 500;
    transition: color var(--transition-fast);
}

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

.contact-form {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 2rem;
    backdrop-filter: blur(8px);
}

.form-group {
    position: relative;
    margin-bottom: 1.5rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 1rem;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    color: var(--text-primary);
    font-family: inherit;
    font-size: 0.9375rem;
    transition: all var(--transition-fast);
    outline: none;
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

.form-group label {
    position: absolute;
    left: 1rem;
    top: 1rem;
    color: var(--text-muted);
    font-size: 0.9375rem;
    pointer-events: none;
    transition: all var(--transition-fast);
    background: var(--bg-input);
    padding: 0 0.25rem;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group input:not(:placeholder-shown),
.form-group textarea:not(:placeholder-shown) {
    border-color: var(--primary);
}

.form-group input:focus ~ label,
.form-group textarea:focus ~ label,
.form-group input:not(:placeholder-shown) ~ label,
.form-group textarea:not(:placeholder-shown) ~ label {
    top: -0.5rem;
    left: 0.75rem;
    font-size: 0.75rem;
    color: var(--primary);
    background: var(--bg-card);
}

/* ========================================
   页脚
   ======================================== */

.footer {
    background: rgba(15, 23, 42, 0.5);
    border-top: 1px solid var(--border-color);
    padding: 4rem 0 2rem;
}

[data-theme="light"] .footer {
    background: rgba(248, 250, 252, 0.5);
}

.footer-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 4rem;
    margin-bottom: 3rem;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.footer-logo i {
    color: var(--primary);
    font-size: 1.5rem;
}

.footer-brand p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    max-width: 300px;
}

.footer-links {
    display: flex;
    gap: 4rem;
}

.footer-links-group h4 {
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: 1rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-muted);
}

.footer-links-group a {
    display: block;
    color: var(--text-secondary);
    font-size: 0.875rem;
    padding: 0.375rem 0;
    transition: color var(--transition-fast);
}

.footer-links-group a:hover {
    color: var(--primary);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.875rem;
}

.footer-bottom i {
    color: var(--danger);
}

.footer-year {
    margin-top: 0.5rem;
}

/* ========================================
   回到顶部
   ======================================== */

.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.125rem;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
    transition: all var(--transition-normal);
    z-index: 999;
    box-shadow: var(--shadow-lg);
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
    box-shadow: var(--shadow-glow);
}

/* ========================================
   动画类
   ======================================== */

.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========================================
   响应式设计
   ======================================== */

@media (max-width: 1024px) {
    .about-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .projects-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .contact-content {
        gap: 2rem;
    }
}

@media (max-width: 768px) {
    :root {
        --section-padding: 60px;
    }

    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        right: 0;
        background: var(--bg-nav);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 1.5rem;
        gap: 0.5rem;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-normal);
        box-shadow: var(--shadow-lg);
    }

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

    .nav-link {
        width: 100%;
        text-align: center;
        padding: 0.75rem;
    }

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

    .hero {
        padding: 5rem 1.5rem 3rem;
    }

    .about-grid {
        grid-template-columns: 1fr;
    }

    .projects-grid {
        grid-template-columns: 1fr;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 1rem;
    }

    .stats-charts {
        grid-template-columns: 1fr;
    }

    .contact-content {
        grid-template-columns: 1fr;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .footer-links {
        gap: 2rem;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        max-width: 280px;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 1rem;
    }

    .avatar-wrapper {
        width: 120px;
        height: 120px;
    }

    .stat-number {
        font-size: 1.75rem;
    }

    .stat-card {
        padding: 1.5rem 1rem;
    }
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    html {
        scroll-behavior: auto;
    }
}