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

:root {
    --primary-color: #6366f1;
    --secondary-color: #8b5cf6;
    --accent-color: #ec4899;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-light: #f9fafb;
    --bg-dark: #111827;
    --white: #ffffff;
    --shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Microsoft YaHei', 'PingFang SC', 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    overflow-x: hidden;
    background: var(--bg-light);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 导航栏 */
.navbar {
    background: var(--white);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: var(--transition);
    backdrop-filter: blur(10px);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
}

.nav-brand h1 {
    font-size: 1.8rem;
    margin: 0;
}

.nav-brand h1 a {
    color: var(--primary-color);
    text-decoration: none;
    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;
}

.brand-subtitle {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-left: 0.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
}

.nav-menu a {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
}

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

.nav-menu a.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.search-icon {
    font-size: 1.2rem;
    color: var(--text-dark);
    text-decoration: none;
    transition: var(--transition);
}

.search-icon:hover {
    color: var(--primary-color);
    transform: scale(1.1);
}

.btn-login,
.btn-user {
    padding: 0.5rem 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: 500;
    transition: var(--transition);
    border: none;
    cursor: pointer;
}

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

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

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

/* 按钮样式 */
.btn-primary {
    display: inline-block;
    padding: 0.75rem 2rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: 600;
    transition: var(--transition);
    border: none;
    cursor: pointer;
}

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

/* 章节样式 */
.section-padding {
    padding: 4rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.section-header p {
    color: var(--text-light);
    font-size: 1.1rem;
}

.bg-light {
    background: var(--bg-light);
}

/* 页脚 */
.footer {
    background: var(--bg-dark);
    color: var(--white);
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
    color: var(--white);
}

.footer-section p {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.8;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section ul li a:hover {
    color: var(--white);
    padding-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: var(--white);
        width: 100%;
        text-align: center;
        transition: var(--transition);
        box-shadow: var(--shadow);
        padding: 2rem 0;
        gap: 1rem;
    }

    .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);
    }

    .section-header h2 {
        font-size: 2rem;
    }

    .nav-actions {
        gap: 0.5rem;
    }

    .btn-login,
    .btn-user {
        padding: 0.4rem 1rem;
        font-size: 0.9rem;
    }
}

/* 平滑滚动动画 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

/* 加载动画 */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(99, 102, 241, 0.3);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
}

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