/* ==========================================
   全局样式
   ========================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 主色调 */
    --primary-color: #667eea;
    --primary-dark: #5568d3;
    --primary-light: #7c93f5;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    
    /* 中性色 */
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-light: #718096;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
    
    /* 渐变色 */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-light: linear-gradient(135deg, #a8edea 0%, #fed6e3 100%);
    
    /* 阴影 */
    --shadow-sm: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    
    /* 字体 */
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Helvetica Neue', Helvetica, Arial, sans-serif;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* 边框圆角 */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* 过渡 */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 300ms ease-in-out;
    --transition-slow: 500ms ease-in-out;
}

html {
    scroll-behavior: smooth;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section {
    padding: var(--spacing-2xl) 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: var(--spacing-xl);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subsection-title {
    font-size: 1.75rem;
    font-weight: 600;
    margin: var(--spacing-xl) 0 var(--spacing-lg);
    color: var(--text-primary);
}

/* ==========================================
   导航栏
   ========================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: var(--transition-base);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm) var(--spacing-lg);
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: var(--transition-fast);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition-base);
}

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

.nav-link:hover::after,
.nav-link.active::after {
    width: 80%;
}

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    border-radius: 3px;
    transition: var(--transition-base);
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #667eea15 0%, #764ba215 100%);
    padding-top: 80px;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

.hero-title .highlight {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-light);
    margin-bottom: var(--spacing-xl);
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition-base);
    display: inline-block;
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
}

.social-link {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    transition: var(--transition-base);
    text-decoration: none;
    font-size: 1.25rem;
}

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

.hero-image {
    display: flex;
    justify-content: center;
}

.profile-card {
    background: white;
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-xl);
    text-align: center;
    animation: float 6s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

.profile-placeholder {
    width: 200px;
    height: 200px;
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 5rem;
    color: white;
    margin-bottom: var(--spacing-lg);
}

.profile-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-number {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-light);
}

/* ==========================================
   关于我
   ========================================== */
.about {
    background: var(--bg-primary);
}

.about-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.about-text p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
    font-size: 1.125rem;
    line-height: 1.8;
    text-align: justify;
}

.about-highlights {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    width: 100%;
}

.highlight-card {
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition-base);
}

.highlight-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.highlight-icon {
    width: 60px;
    height: 60px;
    margin: 0 auto var(--spacing-md);
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.75rem;
}

.highlight-card h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.highlight-card p {
    color: var(--text-light);
    font-size: 0.875rem;
}

/* ==========================================
   教育背景
   ========================================== */
.education {
    background: var(--bg-secondary);
}

.timeline {
    position: relative;
    margin-bottom: var(--spacing-xl);
}

.timeline-item {
    position: relative;
    padding-left: var(--spacing-xl);
}

.timeline-dot {
    position: absolute;
    left: 0;
    top: 8px;
    width: 16px;
    height: 16px;
    background: var(--gradient-primary);
    border-radius: 50%;
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.2);
}

.timeline-content {
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

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

.timeline-header h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.timeline-date {
    color: var(--text-light);
    font-size: 0.875rem;
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
}

.timeline-subtitle {
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: var(--spacing-md);
}

.timeline-details {
    list-style: none;
    padding: 0;
    margin-top: var(--spacing-sm);
}

.timeline-details li {
    padding: var(--spacing-xs) 0;
    color: var(--text-secondary);
    display: flex;
    align-items: flex-start;
}

.timeline-details li strong {
    color: var(--text-primary);
    margin-right: var(--spacing-xs);
    white-space: nowrap;
}

.awards {
    margin-top: var(--spacing-xl);
}

.award-card {
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    display: flex;
    gap: var(--spacing-lg);
    align-items: center;
    transition: var(--transition-base);
}

.award-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.award-icon {
    width: 80px;
    height: 80px;
    background: var(--gradient-secondary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 2.5rem;
    flex-shrink: 0;
}

.award-content h4 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.award-content p {
    color: var(--text-secondary);
}

/* ==========================================
   经历
   ========================================== */
.experience {
    background: var(--bg-primary);
}

.experience-grid {
    display: grid;
    gap: var(--spacing-xl);
}

.experience-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
}

.experience-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-5px);
}

.experience-card.featured {
    background: linear-gradient(135deg, #667eea05 0%, #764ba205 100%);
    border: 2px solid var(--primary-light);
}

.experience-header {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.experience-icon {
    width: 60px;
    height: 60px;
    background: var(--gradient-primary);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.75rem;
    flex-shrink: 0;
}

.experience-info h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.experience-company {
    color: var(--text-secondary);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.experience-date {
    color: var(--text-light);
    font-size: 0.875rem;
}

.experience-achievement {
    margin-bottom: var(--spacing-md);
}

.experience-achievement:last-child {
    margin-bottom: 0;
}

.badge {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.badge-primary {
    background: linear-gradient(135deg, #667eea20, #764ba220);
    color: var(--primary-color);
}

.badge-success {
    background: linear-gradient(135deg, #10b98120, #22c55e20);
    color: #059669;
}

.badge-warning {
    background: linear-gradient(135deg, #f59e0b20, #f97316f20);
    color: #d97706;
}

.badge-info {
    background: linear-gradient(135deg, #3b82f620, #06b6d420);
    color: #0284c7;
}

.experience-achievement p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-top: var(--spacing-xs);
}

.experience-list {
    list-style: none;
    padding: 0;
}

.experience-list li {
    padding: var(--spacing-sm) 0;
    padding-left: var(--spacing-lg);
    color: var(--text-secondary);
    position: relative;
}

.experience-list li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* ==========================================
   技能
   ========================================== */
.skills {
    background: var(--bg-secondary);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.skill-category {
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
}

.skill-category:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.skill-category-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.skill-category-header i {
    font-size: 2rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.skill-category-header h3 {
    font-size: 1.25rem;
    color: var(--text-primary);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.skill-tag {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    color: var(--text-secondary);
    font-size: 0.875rem;
    transition: var(--transition-fast);
    cursor: default;
}

.skill-tag:hover {
    background: var(--gradient-primary);
    color: white;
    transform: translateY(-2px);
}

/* ==========================================
   联系我
   ========================================== */
.contact {
    background: var(--bg-primary);
}

.contact-intro {
    text-align: center;
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
}

.contact-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.contact-card {
    background: white;
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition-base);
}

.contact-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.contact-icon {
    width: 70px;
    height: 70px;
    margin: 0 auto var(--spacing-md);
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 2rem;
}

.contact-card h4 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.contact-card a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition-fast);
}

.contact-card a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.contact-card p {
    color: var(--text-secondary);
}

/* ==========================================
   页脚
   ========================================== */
.footer {
    background: var(--text-primary);
    color: white;
    text-align: center;
    padding: var(--spacing-xl) 0;
}

.footer p {
    margin-bottom: var(--spacing-xs);
}

.footer-subtitle {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.875rem;
}

/* ==========================================
   返回顶部按钮
   ========================================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    box-shadow: var(--shadow-lg);
    transition: var(--transition-base);
    z-index: 999;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.back-to-top.show {
    display: flex;
}

/* ==========================================
   响应式设计
   ========================================== */
@media (max-width: 968px) {
    .hero-content {
        grid-template-columns: 1fr;
    }
    
    .hero-image {
        order: -1;
    }
    
    .about-content {
        grid-template-columns: 1fr;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: var(--transition-base);
        box-shadow: var(--shadow-lg);
        padding: var(--spacing-lg) 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
}

@media (max-width: 768px) {
    .section-title {
        font-size: 2rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .profile-stats {
        grid-template-columns: 1fr;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-cards {
        grid-template-columns: 1fr;
    }
    
    .timeline-header {
        flex-direction: column;
        align-items: flex-start;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .section {
        padding: var(--spacing-xl) 0;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .profile-placeholder {
        width: 150px;
        height: 150px;
        font-size: 4rem;
    }
    
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
    }
}

/* ==========================================
   动画效果
   ========================================== */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn var(--transition-slow) ease-out;
}

/* 打印样式 */
@media print {
    .navbar,
    .back-to-top,
    .hero-buttons,
    .social-links {
        display: none;
    }
    
    .section {
        page-break-inside: avoid;
    }
}

/* ==========================================
   我的频道
   ========================================== */
.channels {
    background: var(--bg-primary);
}

.channels-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
}

.channel-card {
    background: white;
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
    display: flex;
    flex-direction: column;
}

.channel-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.channel-image {
    width: 100%;
    height: 200px;
    background: var(--bg-secondary);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.channel-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.placeholder-img {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-light);
}

.placeholder-img i {
    font-size: 3rem;
    color: #ff0000; /* YouTube red */
}

.channel-info {
    padding: var(--spacing-lg);
    text-align: center;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.channel-info h3 {
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.channel-info p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    flex-grow: 1;
}

.btn-sm {
    padding: var(--spacing-xs) var(--spacing-md);
    font-size: 0.875rem;
}