/* ============================================
   CSS变量 - 设计系统
   ============================================ */
:root {
    /* 主题色 - 静谧蓝 */
    --primary-color: #5B7C99;
    --primary-hover: #4A6580;
    
    /* 黑白灰色系 */
    --color-black: #1A1A1A;
    --color-dark-gray: #333333;
    --color-medium-gray: #666666;
    --color-light-gray: #999999;
    --color-border: #E0E0E0;
    --color-background: #F8F8F8;
    --color-white: #FFFFFF;
    
    /* 字体 */
    --font-primary: 'Open Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    /* 字体大小 */
    --font-size-xs: 12px;
    --font-size-sm: 14px;
    --font-size-base: 16px;
    --font-size-lg: 18px;
    --font-size-xl: 24px;
    --font-size-2xl: 32px;
    --font-size-3xl: 48px;
    
    /* 字重 */
    --font-weight-light: 300;
    --font-weight-regular: 400;
    --font-weight-medium: 600;
    --font-weight-bold: 700;
    
    /* 间距 */
    --spacing-xs: 8px;
    --spacing-sm: 16px;
    --spacing-md: 24px;
    --spacing-lg: 32px;
    --spacing-xl: 48px;
    --spacing-2xl: 64px;
    --spacing-3xl: 96px;
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    
    /* 过渡 */
    --transition-fast: all 0.2s ease;
    --transition-normal: all 0.3s ease;
    --transition-slow: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    
    /* 布局 */
    --container-max-width: 1200px;
    --content-max-width: 720px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-regular);
    line-height: 1.6;
    color: var(--color-dark-gray);
    background: var(--color-white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

a {
    color: inherit;
    text-decoration: none;
    transition: var(--transition-fast);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

/* ============================================
   主导航
   ============================================ */
.site-header {
    position: sticky;
    top: 0;
    background: var(--color-white);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    transition: var(--transition-normal);
}

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

.main-navigation {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 90px;
}

/* Logo */
.site-logo a {
    display: inline-block;
    line-height: 1;
}

.site-logo .logo-image {
    height: 60px;
    width: auto;
    display: block;
}

/* 桌面端菜单 */
.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
    margin: 0;
}

.nav-menu > li {
    position: relative;
}

.nav-menu > li > a {
    display: block;
    padding: var(--spacing-sm) 0;
    font-size: var(--font-size-sm);
    font-weight: var(--font-weight-medium);
    letter-spacing: 0.5px;
    color: var(--color-dark-gray);
    position: relative;
}

/* 下划线动画 */
.nav-menu > li > a::after {
    content: '';
    position: absolute;
    bottom: 8px;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transform: translateX(-50%);
    transition: var(--transition-slow);
}

.nav-menu > li > a:hover::after,
.nav-menu > li > a.active::after {
    width: 100%;
}

.nav-menu > li > a:hover {
    color: var(--primary-color);
}

/* 下拉菜单 */
.sub-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: var(--color-white);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    list-style: none;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: var(--transition-slow);
    padding: var(--spacing-sm) 0;
}

.menu-item-has-children:hover .sub-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.sub-menu li a {
    display: block;
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-sm);
    color: var(--color-dark-gray);
    transition: var(--transition-fast);
}

.sub-menu li a:hover {
    background: var(--color-background);
    color: var(--primary-color);
}

/* 搜索按钮 */
.nav-search button {
    background: none;
    border: none;
    cursor: pointer;
    color: var(--color-dark-gray);
    padding: var(--spacing-xs);
    transition: var(--transition-fast);
}

.nav-search button:hover {
    color: var(--primary-color);
}

/* 移动端菜单按钮 */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.mobile-menu-toggle span {
    width: 25px;
    height: 2px;
    background: var(--color-dark-gray);
    transition: var(--transition-fast);
}

/* ============================================
   Hero区域
   ============================================ */
.hero-section {
    position: relative;
    height: 70vh;
    min-height: 500px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    z-index: 1;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, rgba(0,0,0,0.3), rgba(0,0,0,0.5));
    z-index: 2;
}

.hero-content {
    position: relative;
    z-index: 3;
    text-align: center;
    color: var(--color-white);
    max-width: 800px;
    padding: 0 var(--spacing-md);
}

.hero-title {
    font-size: 56px;
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.hero-subtitle {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-light);
    margin-bottom: var(--spacing-xl);
    opacity: 0.95;
}

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

/* ============================================
   按钮
   ============================================ */
.btn {
    display: inline-block;
    padding: 14px 32px;
    font-size: var(--font-size-base);
    font-weight: var(--font-weight-medium);
    text-align: center;
    border-radius: var(--radius-sm);
    transition: var(--transition-fast);
    cursor: pointer;
    border: 2px solid transparent;
}

.btn:not(.btn-outline) {
    background: var(--primary-color);
    color: var(--color-white);
}

.btn:not(.btn-outline):hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-outline {
    background: transparent;
    color: var(--color-white);
    border-color: var(--color-white);
}

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

/* ============================================
   区块标题
   ============================================ */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section-title {
    font-size: 42px;
    font-weight: var(--font-weight-bold);
    color: var(--color-black);
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-medium-gray);
    font-weight: var(--font-weight-light);
}

/* ============================================
   精选文章区
   ============================================ */
.featured-section {
    padding: var(--spacing-3xl) 0;
}

.articles-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.article-card {
    background: var(--color-white);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: var(--transition-normal);
    border: 1px solid var(--color-border);
}

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

.article-image {
    position: relative;
    overflow: hidden;
    aspect-ratio: 3/4;
}

.article-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-slow);
}

.article-card:hover .article-image img {
    transform: scale(1.05);
}

.article-content {
    padding: var(--spacing-md);
}

.article-category {
    display: inline-block;
    font-size: var(--font-size-xs);
    font-weight: var(--font-weight-medium);
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.article-title {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    color: var(--color-black);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.article-title a {
    color: inherit;
}

.article-title a:hover {
    color: var(--primary-color);
}

.article-excerpt {
    font-size: var(--font-size-sm);
    color: var(--color-medium-gray);
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
}

.article-meta {
    display: flex;
    gap: var(--spacing-md);
    font-size: var(--font-size-xs);
    color: var(--color-light-gray);
}

/* ============================================
   分类展示区
   ============================================ */
.categories-section {
    padding: var(--spacing-3xl) 0;
    background: var(--color-background);
}

.categories-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-md);
}

.category-card {
    position: relative;
    height: 300px;
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: var(--transition-normal);
}

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

.category-card-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-slow);
}

.category-card:hover .category-card-image {
    transform: scale(1.1);
}

.category-card-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    padding: var(--spacing-lg);
    background: linear-gradient(to top, rgba(0,0,0,0.8), transparent);
    color: var(--color-white);
}

.category-card-title {
    font-size: var(--font-size-xl);
    font-weight: var(--font-weight-bold);
    margin-bottom: var(--spacing-xs);
}

.category-card-count {
    font-size: var(--font-size-sm);
    opacity: 0.9;
}

/* ============================================
   页脚
   ============================================ */
.site-footer {
    background: var(--color-dark-gray);
    color: var(--color-light-gray);
    padding: var(--spacing-2xl) 0 var(--spacing-md);
    margin-top: var(--spacing-3xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-section h3 {
    color: var(--color-white);
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
}

.footer-section p {
    font-size: var(--font-size-sm);
    line-height: 1.8;
}

.footer-menu {
    list-style: none;
}

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

.footer-menu a {
    font-size: var(--font-size-sm);
    color: var(--color-light-gray);
}

.footer-menu a:hover {
    color: var(--color-white);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: var(--spacing-md);
    text-align: center;
    font-size: var(--font-size-sm);
}

/* ============================================
   辅助类
   ============================================ */
.text-center {
    text-align: center;
}

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

/* ============================================
   响应式设计
   ============================================ */

/* 平板端 */
@media (max-width: 992px) {
    .articles-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .categories-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .footer-content {
        grid-template-columns: repeat(2, 1fr);
    }
}

/* 移动端 */
@media (max-width: 768px) {
    /* 导航 */
    .main-navigation {
        height: 70px;
    }

    .nav-menu {
        position: fixed;
        top: 70px;
        right: -100%;
        width: 280px;
        height: calc(100vh - 70px);
        background: var(--color-white);
        flex-direction: column;
        padding: var(--spacing-lg);
        box-shadow: var(--shadow-lg);
        transition: var(--transition-normal);
        overflow-y: auto;
    }

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

    .nav-menu > li {
        width: 100%;
    }

    .nav-menu > li > a::after {
        display: none;
    }

    .sub-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        border: none;
        padding-left: var(--spacing-md);
        margin-top: var(--spacing-xs);
        display: none;
    }

    .menu-item-has-children.active .sub-menu {
        display: block;
    }

    .mobile-menu-toggle {
        display: flex;
    }

    .mobile-menu-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .mobile-menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .mobile-menu-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -7px);
    }

    /* Hero */
    .hero-section {
        height: 60vh;
        min-height: 400px;
    }

    .hero-title {
        font-size: 40px;
    }

    .hero-subtitle {
        font-size: var(--font-size-base);
    }

    .hero-cta {
        flex-direction: column;
    }

    .hero-cta .btn {
        width: 100%;
    }

    /* 文章网格 */
    .articles-grid {
        grid-template-columns: 1fr;
    }

    /* 分类网格 */
    .categories-grid {
        grid-template-columns: 1fr;
    }

    /* 页脚 */
    .footer-content {
        grid-template-columns: 1fr;
    }
}

/* 超小屏幕 */
@media (max-width: 480px) {
    .hero-title {
        font-size: 32px;
    }

    .section-title {
        font-size: 36px;
    }

    .category-card {
        height: 250px;
    }
}



/* ============================================
   Header & Navigation
   ============================================ */
.site-header {
    position: sticky;
    top: 0;
    background: #FFFFFF;
    border-bottom: 1px solid #E5E5E5;
    z-index: 1000;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

.header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 90px;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}

.site-logo .logo-image {
    height: 80px;
    width: auto;
}

.main-nav {
    display: flex;
    align-items: center;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
    margin: 0;
    padding: 0;
}

.nav-menu li a {
    font-size: 15px;
    font-weight: 500;
    color: #2D2D2D;
    transition: all 0.15s ease;
    letter-spacing: 0.3px;
}

.nav-menu li a:hover,
.nav-menu li a.active {
    color: #8B9A7E;
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
    color: #2D2D2D;
}

.mobile-nav-overlay {
    display: none;
}

.mobile-nav-menu {
    display: none;
}

/* Dropdown Menu */
.dropdown {
    position: relative;
}

.dropdown-toggle {
    cursor: pointer;
}

.dropdown-toggle .arrow {
    font-size: 10px;
    margin-left: 4px;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    background: #FFFFFF;
    border: 1px solid #E5E5E5;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    min-width: 200px;
    padding: 12px 0;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.3s ease;
    z-index: 1000;
}

.dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-menu a {
    display: block;
    padding: 10px 20px;
    color: #2D2D2D;
    font-size: 14px;
    transition: all 0.2s ease;
}

.dropdown-menu a:hover {
    background: #F8F8F8;
    color: #8B9A7E;
}

.dropdown-divider {
    height: 1px;
    background: #E5E5E5;
    margin: 8px 0;
}

@media (max-width: 768px) {
    .main-nav {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
}

/* ============================================
   Footer
   ============================================ */
.site-footer {
    background: #374151;
    color: #A8A8A8;
    padding: 64px 0 32px;
    margin-top: 80px;
}

.footer-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 32px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 64px;
    margin-bottom: 48px;
}

.footer-about {
    max-width: 400px;
}

.footer-column {
}

.footer-title {
    color: #FFFFFF;
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 20px;
    text-transform: uppercase;
    letter-spacing: 1px;
}

.footer-description {
    font-size: 14px;
    line-height: 1.8;
    margin-bottom: 0;
    color: #B8B8B8;
}

.footer-links {
    list-style: none;
    margin: 0;
    padding: 0;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a {
    color: #B8B8B8;
    font-size: 14px;
    transition: all 0.2s ease;
}

.footer-links a:hover {
    color: #FFFFFF;
    padding-left: 4px;
}

.social-links {
    display: flex;
    gap: 12px;
}

.social-links a {
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    color: #FFFFFF;
    transition: all 0.3s ease;
}

.social-links a:hover {
    background: #8B9A7E;
    transform: translateY(-2px);
}

.newsletter-form {
    display: flex;
    gap: 8px;
    margin-top: 12px;
}

.newsletter-form input {
    flex: 1;
    padding: 10px 14px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 4px;
    background: rgba(255, 255, 255, 0.05);
    color: #FFFFFF;
    font-size: 14px;
}

.newsletter-form input::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

.newsletter-form button {
    padding: 10px 20px;
    background: #8B9A7E;
    color: #FFFFFF;
    border: none;
    border-radius: 4px;
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.newsletter-form button:hover {
    background: #6F7D64;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 32px;
    text-align: center;
}

.footer-bottom p {
    font-size: 13px;
    color: #999999;
}

@media (max-width: 992px) {
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 48px;
    }
    
    .footer-about {
        grid-column: 1 / -1;
        max-width: 100%;
    }
}

@media (max-width: 768px) {
    .site-footer {
        padding: 48px 0 24px;
        margin-top: 64px;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }
    
    .footer-about {
        grid-column: auto;
    }
}