/* ===== 基础样式重置 ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #667eea;
    --primary-dark: #5a67d8;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-light: #718096;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-dark: #1a202c;
    --card-shadow: 0 10px 40px rgba(0, 0, 0, 0.1);
    --card-hover-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease;
    --border-radius: 16px;
    --border-radius-sm: 8px;
}

html {
    scroll-behavior: smooth;
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== 头部导航 ===== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    box-shadow: 0 1px 20px rgba(0, 0, 0, 0.05);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 16px 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
}

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

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    padding: 8px 16px;
    border-radius: var(--border-radius-sm);
    transition: var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
    background: rgba(102, 126, 234, 0.1);
}

/* ===== 主横幅区域 ===== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    padding: 120px 24px 80px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
}

.hero-content {
    text-align: center;
    z-index: 1;
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 5rem);
    font-weight: 700;
    margin-bottom: 24px;
}

.gradient-text {
    background: linear-gradient(135deg, #ffffff 0%, #e0e7ff 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-shadow: 0 4px 30px rgba(0, 0, 0, 0.15);
}

.hero-subtitle {
    font-size: 1.25rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 40px;
    font-weight: 300;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: 14px 32px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: var(--transition);
    cursor: pointer;
}

.btn-primary {
    background: white;
    color: var(--primary-color);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.5);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-3px);
}

/* 浮动卡片装饰 */
.hero-decoration {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    pointer-events: none;
}

.floating-card {
    position: absolute;
    background: rgba(255, 255, 255, 0.95);
    padding: 20px 28px;
    border-radius: var(--border-radius);
    box-shadow: var(--card-shadow);
    display: flex;
    align-items: center;
    gap: 12px;
    animation: float 6s ease-in-out infinite;
}

.floating-card span {
    font-size: 2rem;
}

.floating-card p {
    font-weight: 600;
    color: var(--text-primary);
    white-space: nowrap;
}

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

.card-2 {
    top: 60%;
    right: 8%;
    animation-delay: 2s;
}

.card-3 {
    bottom: 15%;
    left: 15%;
    animation-delay: 4s;
}

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

/* ===== 笔记区域 ===== */
.notes-section {
    padding: 100px 0;
    background: var(--bg-secondary);
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 60px;
    color: var(--text-primary);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -12px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    border-radius: 2px;
}

.notes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
    gap: 32px;
}

.note-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 32px;
    box-shadow: var(--card-shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.note-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transition: var(--transition);
}

.note-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--card-hover-shadow);
}

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

.note-icon {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.note-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.note-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.7;
    margin-bottom: 20px;
}

.note-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.tag {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

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

/* ===== 分类区域 ===== */
.categories-section {
    padding: 100px 0;
    background: var(--bg-primary);
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 24px;
}

.category-card {
    background: linear-gradient(135deg, var(--bg-secondary) 0%, white 100%);
    border-radius: var(--border-radius);
    padding: 32px 24px;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    transition: var(--transition);
    border: 1px solid rgba(0, 0, 0, 0.05);
}

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

.category-icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.category-card h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.category-card p {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* ===== 关于区域 ===== */
.about-section {
    padding: 100px 0;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.about-section .section-title {
    color: white;
}

.about-section .section-title::after {
    background: rgba(255, 255, 255, 0.5);
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
}

.about-text {
    background: rgba(255, 255, 255, 0.95);
    border-radius: var(--border-radius);
    padding: 48px;
    box-shadow: var(--card-shadow);
}

.about-text p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 16px;
    line-height: 1.8;
}

.about-text strong {
    color: var(--primary-color);
}

.about-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
    margin-top: 32px;
    padding-top: 32px;
    border-top: 1px solid rgba(0, 0, 0, 0.1);
}

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

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* ===== 页脚 ===== */
.footer {
    background: var(--bg-dark);
    padding: 48px 0;
}

.footer-content {
    text-align: center;
}

.footer-brand {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-bottom: 16px;
}

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

.footer-brand .logo-text {
    font-size: 1.25rem;
    font-weight: 600;
    color: white;
}

.footer-text {
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.9rem;
    margin-bottom: 8px;
}

.footer-icp {
    margin-top: 8px;
}

.footer-icp a {
    color: rgba(255, 255, 255, 0.5);
    text-decoration: none;
    font-size: 0.85rem;
    transition: var(--transition);
}

.footer-icp a:hover {
    color: rgba(255, 255, 255, 0.8);
}

/* ===== 响应式设计 ===== */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .hero {
        padding: 100px 20px 60px;
    }
    
    .floating-card {
        display: none;
    }
    
    .notes-grid {
        grid-template-columns: 1fr;
    }
    
    .about-stats {
        flex-direction: column;
        gap: 24px;
    }
    
    .about-text {
        padding: 32px 24px;
    }
}

@media (max-width: 480px) {
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn {
        width: 100%;
        max-width: 280px;
        text-align: center;
    }
    
    .categories-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}