/* ========================================
   西夏建筑数字研究平台 - 主样式表
   Western Xia Architecture Research Platform
   ======================================== */

/* CSS Variables */
:root {
    /* 品牌色 - 西夏文化灵感 */
    --color-primary: #8B4513;      /* 陶土棕 - 西夏陶俑 */
    --color-primary-dark: #5D2E0C;
    --color-primary-light: #A65E2E;
    --color-accent: #C9A227;       /* 金色 - 佛教元素 */
    --color-accent-light: #E5C76B;
    
    /* 辅助色 */
    --color-secondary: #2C5F7C;    /* 靛蓝 - 西夏服饰 */
    --color-secondary-light: #4A7A9A;
    --color-tertiary: #6B4423;     /* 深褐 - 建筑木构 */
    
    /* 中性色 */
    --color-bg: #FDFCFA;
    --color-bg-alt: #F5F3EF;
    --color-bg-dark: #1A1A1A;
    --color-text: #2D2D2D;
    --color-text-light: #5A5A5A;
    --color-text-muted: #8A8A8A;
    --color-border: #E5E2DC;
    
    /* 功能色 */
    --color-success: #4A7C59;
    --color-warning: #B8860B;
    --color-error: #8B3A3A;
    
    /* 字体 */
    --font-serif: 'Noto Serif SC', 'Source Han Serif SC', 'SimSun', serif;
    --font-sans: 'Noto Sans SC', 'Source Han Sans SC', 'Microsoft YaHei', sans-serif;
    
    /* 间距 */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
    --space-4xl: 6rem;
    
    /* 圆角 */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --radius-full: 9999px;
    
    /* 阴影 */
    --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 -2px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.1);
    
    /* 过渡 */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    font-size: 1rem;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

ul, ol {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

/* Container */
.container {
    width: 100%;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--space-lg);
}

/* ========================================
   Navigation
   ======================================== */
.main-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(253, 252, 250, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--space-md) var(--space-xl);
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.logo-icon {
    font-size: 1.75rem;
    color: var(--color-primary);
}

.logo-text {
    display: flex;
    flex-direction: column;
}

.logo-main {
    font-family: var(--font-serif);
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
    line-height: 1.3;
}

.logo-sub {
    font-size: 0.625rem;
    color: var(--color-text-muted);
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--space-xs);
}

.nav-links a {
    padding: var(--space-sm) var(--space-md);
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-light);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--color-primary);
    background: rgba(139, 69, 19, 0.08);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.btn-search {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-full);
    color: var(--color-text-light);
    transition: all var(--transition-fast);
}

.btn-search:hover {
    background: var(--color-bg-alt);
    color: var(--color-primary);
}

.btn-login {
    padding: var(--space-sm) var(--space-lg);
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-primary);
    border: 1.5px solid var(--color-primary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

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

/* ========================================
   Hero Section
   ======================================== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 72px;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, #FDFCFA 0%, #F5F0E8 50%, #EDE5D8 100%);
}

.hero-pattern {
    position: absolute;
    inset: 0;
    opacity: 0.03;
    background-image: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M30 0L60 30L30 60L0 30L30 0z' fill='%238B4513' fill-opacity='1'/%3E%3C/svg%3E");
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--space-4xl) var(--space-xl);
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-4xl);
    align-items: center;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: var(--space-sm) var(--space-md);
    background: rgba(201, 162, 39, 0.15);
    border: 1px solid rgba(201, 162, 39, 0.3);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    color: var(--color-tertiary);
    margin-bottom: var(--space-xl);
}

.badge-icon {
    color: var(--color-accent);
}

.hero-title {
    margin-bottom: var(--space-lg);
}

.title-main {
    display: block;
    font-family: var(--font-serif);
    font-size: 4rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.1;
    letter-spacing: 0.05em;
}

.title-sub {
    display: block;
    font-family: var(--font-sans);
    font-size: 2rem;
    font-weight: 300;
    color: var(--color-text-light);
    margin-top: var(--space-sm);
    letter-spacing: 0.1em;
}

.hero-desc {
    font-size: 1.125rem;
    color: var(--color-text-light);
    line-height: 1.8;
    margin-bottom: var(--space-2xl);
    max-width: 540px;
}

.hero-stats {
    display: flex;
    gap: var(--space-2xl);
    margin-bottom: var(--space-2xl);
}

.stat-item {
    display: flex;
    flex-direction: column;
}

.stat-number {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-top: var(--space-xs);
}

.hero-actions {
    display: flex;
    gap: var(--space-md);
}

/* Hero Visual - Tomb Structure */
.hero-visual {
    display: flex;
    align-items: center;
    justify-content: center;
}

.tomb-preview {
    position: relative;
    width: 320px;
    height: 400px;
}

.tomb-structure {
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-end;
}

.tomb-level {
    background: linear-gradient(180deg, #A67B5B 0%, #8B6914 100%);
    border-radius: 4px;
    box-shadow: 0 4px 20px rgba(139, 69, 19, 0.3);
}

.level-3 {
    width: 80px;
    height: 60px;
    clip-path: polygon(50% 0%, 100% 100%, 0% 100%);
    background: linear-gradient(180deg, #C9A227 0%, #A67B5B 100%);
}

.level-2 {
    width: 160px;
    height: 80px;
    margin-top: -10px;
}

.level-1 {
    width: 240px;
    height: 100px;
    margin-top: -10px;
}

.tomb-base {
    width: 280px;
    height: 40px;
    background: linear-gradient(180deg, #6B4423 0%, #4A3728 100%);
    border-radius: 4px;
    margin-top: -5px;
}

.tomb-glow {
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 400px;
    height: 200px;
    background: radial-gradient(ellipse at center, rgba(201, 162, 39, 0.2) 0%, transparent 70%);
    pointer-events: none;
}

/* ========================================
   Buttons
   ======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-sm);
    padding: var(--space-md) var(--space-xl);
    font-size: 1rem;
    font-weight: 500;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.btn-primary {
    background: var(--color-primary);
    color: white;
    box-shadow: 0 4px 14px rgba(139, 69, 19, 0.3);
}

.btn-primary:hover {
    background: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(139, 69, 19, 0.4);
}

.btn-secondary {
    background: transparent;
    color: var(--color-primary);
    border: 1.5px solid var(--color-primary);
}

.btn-secondary:hover {
    background: rgba(139, 69, 19, 0.08);
}

.btn-outline {
    background: transparent;
    color: var(--color-primary);
    border: 1px solid var(--color-border);
}

.btn-outline:hover {
    border-color: var(--color-primary);
    background: rgba(139, 69, 19, 0.05);
}

.btn-small {
    padding: var(--space-sm) var(--space-md);
    font-size: 0.875rem;
}

/* ========================================
   Section Styles
   ======================================== */
section {
    padding: var(--space-4xl) 0;
}

.section-header {
    text-align: center;
    max-width: 640px;
    margin: 0 auto var(--space-3xl);
}

.section-tag {
    display: inline-block;
    padding: var(--space-xs) var(--space-md);
    background: rgba(139, 69, 19, 0.08);
    color: var(--color-primary);
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: var(--radius-full);
    margin-bottom: var(--space-md);
}

.section-header h2 {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-md);
}

.section-header p {
    font-size: 1.125rem;
    color: var(--color-text-light);
}

/* ========================================
   Features Section
   ======================================== */
.features {
    background: var(--color-bg-alt);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-xl);
}

.feature-card {
    background: white;
    padding: var(--space-2xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    border: 1px solid var(--color-border);
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--color-primary-light);
}

.feature-icon {
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, rgba(139, 69, 19, 0.1) 0%, rgba(201, 162, 39, 0.1) 100%);
    border-radius: var(--radius-md);
    color: var(--color-primary);
    margin-bottom: var(--space-lg);
}

.feature-card h3 {
    font-family: var(--font-serif);
    font-size: 1.375rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-md);
}

.feature-card > p {
    color: var(--color-text-light);
    line-height: 1.7;
    margin-bottom: var(--space-lg);
}

.feature-meta {
    display: flex;
    gap: var(--space-sm);
    margin-bottom: var(--space-lg);
}

.meta-item {
    padding: var(--space-xs) var(--space-sm);
    background: var(--color-bg-alt);
    color: var(--color-text-muted);
    font-size: 0.75rem;
    border-radius: var(--radius-sm);
}

.feature-link {
    font-weight: 500;
    color: var(--color-primary);
    transition: all var(--transition-fast);
}

.feature-link:hover {
    color: var(--color-primary-dark);
    padding-left: var(--space-sm);
}

/* ========================================
   Publications Section
   ======================================== */
.publications {
    background: white;
}

.pub-tabs {
    display: flex;
    justify-content: center;
    gap: var(--space-sm);
    margin-bottom: var(--space-2xl);
}

.tab-btn {
    padding: var(--space-sm) var(--space-lg);
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-text-light);
    border-radius: var(--radius-full);
    transition: all var(--transition-fast);
}

.tab-btn:hover {
    color: var(--color-primary);
    background: rgba(139, 69, 19, 0.05);
}

.tab-btn.active {
    color: white;
    background: var(--color-primary);
}

.pub-list {
    display: none;
}

.pub-list.active {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-xl);
}

.pub-item {
    padding: var(--space-xl);
    background: var(--color-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    transition: all var(--transition-fast);
}

.pub-item:hover {
    border-color: var(--color-primary-light);
    box-shadow: var(--shadow-md);
}

.pub-type {
    display: inline-block;
    padding: var(--space-xs) var(--space-sm);
    background: rgba(44, 95, 124, 0.1);
    color: var(--color-secondary);
    font-size: 0.75rem;
    font-weight: 500;
    border-radius: var(--radius-sm);
    margin-bottom: var(--space-md);
}

.pub-title {
    font-family: var(--font-serif);
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
    line-height: 1.5;
    margin-bottom: var(--space-sm);
}

.pub-authors,
.pub-source {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-bottom: var(--space-xs);
}

.pub-meta {
    display: flex;
    gap: var(--space-md);
    margin: var(--space-md) 0;
    padding-top: var(--space-md);
    border-top: 1px solid var(--color-border);
    font-size: 0.8125rem;
    color: var(--color-text-muted);
}

.pub-actions {
    display: flex;
    gap: var(--space-sm);
}

.pub-more {
    text-align: center;
    margin-top: var(--space-2xl);
}

/* ========================================
   Data Update Section
   ======================================== */
.data-update {
    background: linear-gradient(180deg, var(--color-bg-alt) 0%, var(--color-bg) 100%);
}

.update-flow {
    display: flex;
    align-items: flex-start;
    justify-content: center;
    gap: var(--space-md);
    margin-bottom: var(--space-3xl);
    flex-wrap: wrap;
}

.flow-step {
    flex: 1;
    min-width: 220px;
    max-width: 260px;
    text-align: center;
    padding: var(--space-xl);
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    position: relative;
}

.step-number {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-primary);
    color: white;
    font-size: 0.75rem;
    font-weight: 700;
    border-radius: var(--radius-full);
}

.step-icon {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.flow-step h3 {
    font-family: var(--font-serif);
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-md);
}

.flow-step ul {
    text-align: left;
}

.flow-step li {
    font-size: 0.875rem;
    color: var(--color-text-light);
    padding: var(--space-xs) 0;
    padding-left: var(--space-md);
    position: relative;
}

.flow-step li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--color-accent);
}

.flow-arrow {
    font-size: 1.5rem;
    color: var(--color-accent);
    align-self: center;
}

.update-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-lg);
    max-width: 900px;
    margin: 0 auto;
}

.update-item {
    text-align: center;
    padding: var(--space-lg);
    background: white;
    border-radius: var(--radius-md);
    border: 1px solid var(--color-border);
}

.update-label {
    display: block;
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-bottom: var(--space-xs);
}

.update-value {
    display: block;
    font-family: var(--font-serif);
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-primary);
}

/* ========================================
   Tools Section
   ======================================== */
.tools {
    background: white;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-lg);
}

.tool-card {
    padding: var(--space-xl);
    background: var(--color-bg);
    border-radius: var(--radius-lg);
    border: 1px solid var(--color-border);
    transition: all var(--transition-base);
}

.tool-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary-light);
}

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

.tool-badge {
    padding: var(--space-xs) var(--space-sm);
    background: rgba(201, 162, 39, 0.15);
    color: var(--color-tertiary);
    font-size: 0.6875rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.tool-card h3 {
    font-family: var(--font-serif);
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--color-text);
}

.tool-card > p {
    font-size: 0.9375rem;
    color: var(--color-text-light);
    line-height: 1.6;
    margin-bottom: var(--space-md);
}

.tool-features {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-xs);
    margin-bottom: var(--space-lg);
}

.tool-features span {
    padding: var(--space-xs) var(--space-sm);
    background: white;
    color: var(--color-text-muted);
    font-size: 0.75rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--color-border);
}

/* ========================================
   Partners Section
   ======================================== */
.partners {
    background: var(--color-bg-alt);
}

.partners-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-lg);
}

.partner-card {
    padding: var(--space-xl);
    background: white;
    border-radius: var(--radius-lg);
    text-align: center;
    border: 1px solid var(--color-border);
    transition: all var(--transition-fast);
}

.partner-card:hover {
    border-color: var(--color-primary-light);
    box-shadow: var(--shadow-md);
}

.partner-logo {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.partner-card h4 {
    font-family: var(--font-serif);
    font-size: 1.0625rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--space-xs);
}

.partner-card p {
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

/* ========================================
   Footer
   ======================================== */
.main-footer {
    background: var(--color-bg-dark);
    color: var(--color-text-muted);
    padding: var(--space-4xl) 0 var(--space-xl);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: var(--space-3xl);
    margin-bottom: var(--space-3xl);
}

.footer-brand .logo {
    margin-bottom: var(--space-lg);
}

.footer-brand .logo-main {
    color: white;
}

.footer-brand > p {
    line-height: 1.8;
    margin-bottom: var(--space-lg);
}

.footer-contact p {
    margin-bottom: var(--space-xs);
}

.footer-links h4 {
    color: white;
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--space-lg);
}

.footer-links li {
    margin-bottom: var(--space-sm);
}

.footer-links a {
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--color-accent-light);
}

.footer-bottom {
    padding-top: var(--space-xl);
    border-top: 1px solid rgba(255,255,255,0.1);
    text-align: center;
    font-size: 0.875rem;
}

.footer-bottom p:first-child {
    margin-bottom: var(--space-xs);
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1200px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-stats {
        justify-content: center;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .hero-visual {
        display: none;
    }
    
    .title-main {
        font-size: 3rem;
    }
    
    .title-sub {
        font-size: 1.5rem;
    }
}

@media (max-width: 992px) {
    .nav-links {
        display: none;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .pub-list.active {
        grid-template-columns: 1fr;
    }
    
    .tools-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .partners-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .update-flow {
        flex-direction: column;
        align-items: center;
    }
    
    .flow-arrow {
        transform: rotate(90deg);
    }
    
    .update-stats {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 576px) {
    .hero-stats {
        flex-wrap: wrap;
        gap: var(--space-lg);
    }
    
    .tools-grid {
        grid-template-columns: 1fr;
    }
    
    .partners-grid {
        grid-template-columns: 1fr;
    }
    
    .update-stats {
        grid-template-columns: 1fr;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
    }
    
    .title-main {
        font-size: 2.25rem;
    }
    
    .title-sub {
        font-size: 1.125rem;
    }
}

/* ========================================
   Animations
   ======================================== */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.7;
    }
}

.animate-fadeInUp {
    animation: fadeInUp 0.6s ease forwards;
}

/* Scroll reveal */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}