:root {
    --primary: #2563eb;
    --primary-light: #3b82f6;
    --primary-dark: #1d4ed8;
    --secondary: #6366f1;
    --accent: #8b5cf6;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;

    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-light: #f8fafc;

    --bg-primary: #ffffff;
    --bg-secondary: #f1f5f9;
    --bg-tertiary: #e2e8f0;

    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --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);

    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans", Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
    line-height: 1.5;
    font-weight: 400;
    color: var(--text-primary);
    background-color: #f5f7fa;
    font-synthesis: none;
    text-rendering: optimizeLegibility;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* 自定义滚动条 */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: #a1a1a1;
}

/* 全局动画 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in {
    animation: fadeIn 0.6s ease-out forwards;
}

/* 渐变背景 */
.gradient-bg {
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
}

/* 悬停效果 */
.card-hover {
    transition: all 0.3s ease;
}

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

/* 通用类 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.relative.group .dropdown {
    opacity: 0;
    transform: translateY(-6px);
    transition: opacity .16s ease, transform .16s ease;
    pointer-events: none;
    /* 默认不可点 */
}

.relative.group.open .dropdown {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
    /* 展开时可交互 */
}

.flex {
    display: flex;
}

.flex-col {
    flex-direction: column;
}

.items-center {
    align-items: center;
}

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

.justify-between {
    justify-content: space-between;
}

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

.font-bold {
    font-weight: 700;
}

.font-semibold {
    font-weight: 600;
}

.rounded-xl {
    border-radius: var(--radius-xl);
}

.rounded-2xl {
    border-radius: var(--radius-2xl);
}

.rounded-full {
    border-radius: 9999px;
}

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

.shadow-lg {
    box-shadow: var(--shadow-lg);
}

.shadow-xl {
    box-shadow: var(--shadow-xl);
}

.transition-all {
    transition: all 0.3s ease;
}

/* 导航栏 */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 50;
    background-color: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(8px);
    box-shadow: var(--shadow-sm);
}

.nav-container {
    padding: 0.75rem 1rem;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-logo-icon {
    background-color: var(--primary);
    color: white;
    padding: 0.5rem;
    border-radius: var(--radius-lg);
}

.nav-logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    background: linear-gradient(to right, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.nav-links {
    display: none;
    gap: 1.5rem;
}

@media (min-width: 768px) {
    .nav-links {
        display: flex;
    }
}

.nav-link {
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: color 0.2s ease;
}

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

.nav-toggle {
    display: block;
    background: none;
    border: none;
    color: var(--text-primary);
    cursor: pointer;
}

@media (min-width: 768px) {
    .nav-toggle {
        display: none;
    }
}

.nav-dropdown {
    display: none;
    background-color: white;
    box-shadow: var(--shadow-lg);
}

.nav-dropdown.show {
    display: block;
}

.nav-dropdown-container {
    padding: 0.5rem 0;
}

.nav-dropdown-link {
    display: block;
    padding: 0.75rem 1rem;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all 0.2s ease;
}

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

/* 英雄区域 */
.hero {
    padding-top: 8rem;
    padding-bottom: 5rem;
}

@media (min-width: 768px) {
    .hero {
        padding-top: 10rem;
        padding-bottom: 8rem;
    }
}

.hero-content {
    max-width: 4xl;
    margin: 0 auto;
    text-align: center;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

@media (min-width: 768px) {
    .hero-title {
        font-size: 3rem;
    }
}

@media (min-width: 1024px) {
    .hero-title {
        font-size: 3.5rem;
    }
}

.hero-title-gradient {
    background: linear-gradient(to right, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.hero-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    line-height: 1.6;
}

@media (min-width: 768px) {
    .hero-subtitle {
        font-size: 1.25rem;
    }
}

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

.btn {
    padding: 0.75rem 2rem;
    font-weight: 500;
    border-radius: var(--radius-xl);
    border: none;
    cursor: pointer;
    transition: all 0.2s ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    box-shadow: var(--shadow-xl);
}

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

.btn-secondary:hover {
    background-color: var(--bg-secondary);
    box-shadow: var(--shadow-lg);
}

/* 亮点概览 */
.highlights {
    margin-top: 5rem;
    display: grid;
    grid-template-columns: 1fr;
    gap: 1.5rem;
}

@media (min-width: 768px) {
    .highlights {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (min-width: 1024px) {
    .highlights {
        grid-template-columns: repeat(5, 1fr);
    }
}

.highlight-card {
    background-color: white;
    padding: 1.5rem;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    transition: all 0.3s ease;
}

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

.highlight-icon {
    width: 3rem;
    height: 3rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: rgba(59, 130, 246, 0.1);
    color: var(--primary);
    border-radius: 50%;
    margin-bottom: 1rem;
}

.highlight-title {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.highlight-desc {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* 通用章节样式 */
.section {
    padding: 5rem 1rem;
}

.section-white {
    background-color: white;
}

.section-header {
    text-align: center;
    max-width: 3xl;
    margin: 0 auto 3rem;
}

.section-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 4rem;
    height: 4rem;
    background-color: rgba(59, 130, 246, 0.1);
    color: var(--primary);
    border-radius: 50%;
    margin-bottom: 1rem;
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

@media (min-width: 768px) {
    .section-title {
        font-size: 2.5rem;
    }
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* 卡片网格 */
.cards-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
    margin-bottom: 4rem;
}

@media (min-width: 768px) {
    .cards-grid.cols-2 {
        grid-template-columns: repeat(2, 1fr);
    }

    .cards-grid.cols-3 {
        grid-template-columns: repeat(3, 1fr);
    }
}

.feature-card {
    background-color: white;
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    transition: all 0.3s ease;
    border: 1px solid var(--bg-tertiary);
}

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

.feature-card-content {
    padding: 1.5rem;
}

.feature-icon {
    width: 3.5rem;
    height: 3.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: rgba(59, 130, 246, 0.1);
    color: var(--primary);
    border-radius: var(--radius-xl);
    margin-bottom: 1rem;
}

.feature-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.feature-description {
    color: var(--text-secondary);
    margin-bottom: 1.25rem;
}

.feature-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.feature-item {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
}

.feature-item-icon {
    color: var(--success);
    margin-top: 0.125rem;
    flex-shrink: 0;
}

.feature-item-text {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* 章节图片 */
.section-image {
    margin-top: 4rem;
    border-radius: var(--radius-2xl);
    overflow: hidden;
    box-shadow: var(--shadow-xl);
}

.section-image img {
    width: 100%;
    height: auto;
    display: block;
}

/* CTA 区域 */
.cta {
    background: linear-gradient(to right, var(--primary), var(--secondary));
    color: white;
    padding: 5rem 1rem;
}

.cta-content {
    max-width: 2xl;
    margin: 0 auto;
    text-align: center;
}

.cta-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
}

@media (min-width: 768px) {
    .cta-title {
        font-size: 2.5rem;
    }
}

.cta-subtitle {
    font-size: 1.125rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 2.5rem;
}

.cta-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
}

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

.btn-cta-primary:hover {
    background-color: rgba(255, 255, 255, 0.9);
    box-shadow: var(--shadow-xl);
}

.btn-cta-secondary {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    box-shadow: var(--shadow-lg);
}

.btn-cta-secondary:hover {
    background-color: rgba(255, 255, 255, 0.3);
    box-shadow: var(--shadow-xl);
}

/* 页脚 */
.footer {
    background-color: #0f172a;
    color: #94a3b8;
    padding: 3rem 1rem;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
}

@media (min-width: 768px) {
    .footer-content {
        flex-direction: row;
        justify-content: space-between;
    }
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.footer-logo-icon {
    background-color: var(--primary);
    color: white;
    padding: 0.5rem;
    border-radius: var(--radius-lg);
}

.footer-logo-text {
    font-size: 1.25rem;
    font-weight: 700;
    color: white;
}

.footer-copyright {
    font-size: 0.875rem;
}

/* 响应式调整 */
@media (max-width: 767px) {
    .container {
        padding: 0 0.5rem;
    }

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

    .section-subtitle,
    .hero-subtitle {
        font-size: 1rem;
    }

    .btn {
        padding: 0.625rem 1.5rem;
        font-size: 0.875rem;
    }
}