/* ============================================
   AI学习笔记网站 - 主样式表
   采用现代渐变设计风格
   ============================================ */

/* CSS变量定义 */
:root {
    /* 主色调 - 紫蓝渐变 */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    
    /* 辅助色 */
    --accent-color: #f093fb;
    --success-color: #4ade80;
    --warning-color: #fbbf24;
    
    /* 背景色 */
    --bg-primary: #0f0f1a;
    --bg-secondary: #1a1a2e;
    --bg-card: #16162a;
    --bg-hover: #252545;
    
    /* 文字色 */
    --text-primary: #ffffff;
    --text-secondary: #a0a0b0;
    --text-muted: #6b7280;
    
    /* 边框和阴影 */
    --border-color: rgba(255, 255, 255, 0.1);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 30px rgba(102, 126, 234, 0.3);
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 5rem;
    
    /* 圆角 */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-full: 50%;
    
    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* ============================================
   导航栏
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(15, 15, 26, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    transition: var(--transition-normal);
}

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

.nav-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    text-decoration: none;
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 700;
    transition: var(--transition-fast);
}

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

.logo-icon {
    font-size: 1.5rem;
}

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

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

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

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

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

/* 汉堡菜单 */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: var(--spacing-xs);
}

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

/* ============================================
   主页英雄区
   ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xxl) var(--spacing-lg);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 50%, rgba(102, 126, 234, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 80% 50%, rgba(118, 75, 162, 0.15) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    text-align: center;
    max-width: 800px;
    z-index: 1;
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 4.5rem);
    font-weight: 800;
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

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

.hero-subtitle {
    font-size: clamp(1rem, 3vw, 1.25rem);
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition-normal);
    border: none;
    min-width: 140px;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 25px rgba(102, 126, 234, 0.5);
}

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

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

/* 浮动卡片装饰 */
.hero-decoration {
    position: absolute;
    width: 100%;
    height: 100%;
    pointer-events: none;
    overflow: hidden;
}

.floating-card {
    position: absolute;
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: var(--shadow-md);
    animation: float 6s ease-in-out infinite;
}

.card-1 {
    top: 20%;
    left: 10%;
    animation-delay: 0s;
}

.card-2 {
    top: 30%;
    right: 10%;
    animation-delay: 1.5s;
}

.card-3 {
    bottom: 30%;
    left: 15%;
    animation-delay: 3s;
}

.card-4 {
    bottom: 25%;
    right: 15%;
    animation-delay: 4.5s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(2deg);
    }
}

/* ============================================
   统计区
   ============================================ */
.stats {
    padding: var(--spacing-xl) var(--spacing-lg);
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.stats-container {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
    gap: var(--spacing-lg);
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 3rem;
    font-weight: 800;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* ============================================
   通用区块样式
   ============================================ */
section {
    padding: var(--spacing-xxl) var(--spacing-lg);
}

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

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* ============================================
   学习笔记区
   ============================================ */
.notes-section {
    max-width: 1200px;
    margin: 0 auto;
}

.category-tags {
    display: flex;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    flex-wrap: wrap;
}

.tag {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-full);
    color: var(--text-secondary);
    cursor: pointer;
    transition: var(--transition-fast);
    font-size: 0.9rem;
}

.tag:hover,
.tag.active {
    background: var(--primary-gradient);
    border-color: transparent;
    color: white;
}

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

.note-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: var(--transition-normal);
    cursor: pointer;
}

.note-card:hover {
    transform: translateY(-5px);
    border-color: var(--primary-color);
    box-shadow: var(--shadow-glow);
}

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

.note-category {
    padding: 4px 12px;
    background: rgba(102, 126, 234, 0.2);
    color: var(--primary-color);
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 600;
}

.note-date {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.note-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    line-height: 1.4;
}

.note-excerpt {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.note-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-sm);
    border-top: 1px solid var(--border-color);
}

.read-more {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 4px;
    transition: var(--transition-fast);
}

.read-more:hover {
    gap: 8px;
}

/* ============================================
   项目展示区
   ============================================ */
.projects-section {
    background: var(--bg-secondary);
}

.projects-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

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

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

.project-image {
    height: 160px;
    background: var(--primary-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
}

.project-icon {
    font-size: 4rem;
}

.project-info {
    padding: var(--spacing-lg);
}

.project-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.project-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-md);
    line-height: 1.5;
}

.project-tags {
    display: flex;
    gap: var(--spacing-xs);
    flex-wrap: wrap;
    margin-bottom: var(--spacing-md);
}

.project-tag {
    padding: 4px 10px;
    background: var(--bg-hover);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.project-link {
    display: inline-flex;
    align-items: center;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition-fast);
}

.project-link:hover {
    gap: 8px;
}

/* ============================================
   关于我
   ============================================ */
.about-section {
    max-width: 900px;
    margin: 0 auto;
}

.about-container {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
}

.about-image {
    flex-shrink: 0;
}

.avatar {
    width: 150px;
    height: 150px;
    background: var(--primary-gradient);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    box-shadow: var(--shadow-glow);
}

.about-content {
    flex: 1;
}

.about-content .section-title {
    text-align: left;
    margin-bottom: var(--spacing-md);
}

.about-text {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-lg);
}

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

.social-link {
    width: 45px;
    height: 45px;
    background: var(--bg-hover);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    text-decoration: none;
    transition: var(--transition-fast);
}

.social-link:hover {
    background: var(--primary-gradient);
    border-color: transparent;
    transform: translateY(-3px);
}

/* ============================================
   页脚
   ============================================ */
.footer {
    background: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: var(--spacing-xl) var(--spacing-lg);
    text-align: center;
}

.footer-text {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

.footer-subtext {
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* ============================================
   提示弹窗
   ============================================ */
.toast {
    position: fixed;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 2000;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast-message {
    color: var(--text-primary);
    font-weight: 500;
}

/* ============================================
   响应式设计
   ============================================ */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: var(--bg-secondary);
        width: 100%;
        text-align: center;
        transition: var(--transition-normal);
        padding: var(--spacing-lg) 0;
        border-bottom: 1px solid var(--border-color);
    }

    .nav-menu.active {
        left: 0;
    }

    .hamburger {
        display: flex;
    }

    .hamburger.active .bar:nth-child(1) {
        transform: rotate(-45deg) translate(-5px, 6px);
    }

    .hamburger.active .bar:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active .bar:nth-child(3) {
        transform: rotate(45deg) translate(-5px, -6px);
    }

    .floating-card {
        display: none;
    }

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

    .btn {
        width: 100%;
        max-width: 250px;
    }

    .stats-container {
        flex-direction: column;
        gap: var(--spacing-md);
    }

    .about-container {
        flex-direction: column;
        text-align: center;
    }

    .about-content .section-title {
        text-align: center;
    }

    .social-links {
        justify-content: center;
    }

    section {
        padding: var(--spacing-xl) var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .notes-grid,
    .projects-grid {
        grid-template-columns: 1fr;
    }

    .category-tags {
        justify-content: flex-start;
        overflow-x: auto;
        flex-wrap: nowrap;
        padding-bottom: var(--spacing-xs);
    }

    .section-title {
        font-size: 1.75rem;
    }
}

/* ============================================
   动画效果
   ============================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.note-card,
.project-card {
    animation: fadeInUp 0.6s ease forwards;
}

/* 滚动条美化 */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
    background: var(--bg-hover);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}