/* ========================================
   零一万物官网样式表
   字体：思源黑体 (Noto Sans SC)
   ======================================== */

/* CSS Reset & 基础样式 */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 颜色变量 */
    --color-primary: #000000;
    --color-secondary: #333333;
    --color-text: #4a4a4a;
    --color-text-light: #666666;
    --color-border: #e5e5e5;
    --color-bg: #ffffff;
    --color-bg-light: #f8f9fa;
    --color-accent: #0066ff;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* 字体 */
    --font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: 16px;
    line-height: 1.6;
    color: var(--color-text);
    background-color: var(--color-bg);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

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

ul {
    list-style: none;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    font-size: 1rem;
    font-weight: 500;
    border-radius: 4px;
    transition: all var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background-color: var(--color-secondary);
    transform: translateY(-2px);
}

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

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

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

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

/* ========================================
   导航栏
   ======================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    padding: var(--spacing-sm) 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-primary);
}

.logo-text {
    letter-spacing: 0.5px;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-link {
    font-size: 0.95rem;
    color: var(--color-text);
    font-weight: 400;
    position: relative;
    padding: 0.25rem 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-primary);
    transition: width var(--transition-normal);
}

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

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

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

.lang-switcher {
    display: flex;
    align-items: center;
    gap: 4px;
}

.lang-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--color-text);
    padding: 0.25rem 0.5rem;
    transition: all var(--transition-fast);
    font-family: var(--font-family);
}

.lang-btn:hover {
    color: var(--color-primary);
}

.lang-btn.active {
    color: var(--color-primary);
    font-weight: 700;
}

.lang-divider {
    color: var(--color-border);
    font-size: 0.95rem;
}

.lang-switch {
    font-size: 0.95rem;
    color: var(--color-text);
    font-weight: 500;
}

.lang-switch:hover {
    color: var(--color-primary);
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.mobile-menu-btn span {
    width: 24px;
    height: 2px;
    background-color: var(--color-primary);
    transition: all var(--transition-normal);
}

/* ========================================
   Hero 区域
   ======================================== */
.hero {
    padding: 120px 0 80px;
    background: linear-gradient(135deg, #f8f9fa 0%, #ffffff 100%);
    min-height: 80vh;
    display: flex;
    align-items: center;
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
}

.hero-content {
    max-width: 600px;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--color-primary);
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--color-text);
    margin-bottom: var(--spacing-sm);
}

.hero-slogan {
    font-size: 1.125rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-lg);
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
}

.hero-visual {
    display: flex;
    justify-content: center;
    align-items: center;
}

.hero-graphic {
    width: 400px;
    height: 400px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 50%;
    position: relative;
    overflow: hidden;
}

.hero-graphic::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80%;
    height: 80%;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: translate(-50%, -50%) scale(1);
        opacity: 0.5;
    }
    50% {
        transform: translate(-50%, -50%) scale(1.1);
        opacity: 0.3;
    }
}

/* ========================================
   新闻中心
   ======================================== */
.news-section {
    padding: var(--spacing-2xl) 0;
    background-color: var(--color-bg);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--color-primary);
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

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

.news-card {
    padding: var(--spacing-lg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    transition: all var(--transition-normal);
    background-color: var(--color-bg);
}

.news-card:hover {
    border-color: var(--color-primary);
    transform: translateY(-4px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.news-card.featured {
    grid-column: span 2;
    background-color: var(--color-bg-light);
}

.news-date {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-sm);
}

.news-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
    line-height: 1.4;
}

.news-excerpt {
    font-size: 0.95rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.news-link {
    font-size: 0.95rem;
    color: var(--color-accent);
    font-weight: 500;
}

.news-link:hover {
    text-decoration: underline;
}

/* ========================================
   Yi 基座模型
   ======================================== */
.models-section {
    padding: var(--spacing-2xl) 0;
    background-color: var(--color-bg-light);
}

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

.model-card {
    padding: var(--spacing-xl);
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    text-align: center;
    transition: all var(--transition-normal);
    position: relative;
}

.model-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}

.model-card.highlight {
    border-color: var(--color-primary);
    background: linear-gradient(135deg, #f8f9fa 0%, #ffffff 100%);
}

.model-badge {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    background-color: var(--color-primary);
    color: var(--color-bg);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.model-name {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.model-desc {
    font-size: 1rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
}

.model-features {
    text-align: left;
    margin-bottom: var(--spacing-lg);
}

.model-features li {
    padding: 0.5rem 0;
    color: var(--color-text);
    position: relative;
    padding-left: 1.5rem;
}

.model-features li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--color-accent);
    font-weight: 700;
}

/* ========================================
   愿景区域
   ======================================== */
.vision-section {
    padding: var(--spacing-2xl) 0;
    background: linear-gradient(135deg, #000000 0%, #333333 100%);
    color: var(--color-bg);
    text-align: center;
}

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

.vision-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
}

.vision-text {
    font-size: 1.75rem;
    font-weight: 500;
    margin-bottom: var(--spacing-md);
    line-height: 1.4;
}

.vision-subtext {
    font-size: 1.125rem;
    opacity: 0.8;
}

/* ========================================
   页脚
   ======================================== */
.footer {
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
    background-color: var(--color-bg);
    border-top: 1px solid var(--color-border);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-heading {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
}

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

.footer-links a {
    font-size: 0.95rem;
    color: var(--color-text-light);
}

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

.footer-bottom {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
}

.footer-info p {
    font-size: 0.875rem;
    color: var(--color-text-light);
    margin-bottom: 0.5rem;
}

.footer-info a {
    color: var(--color-text-light);
}

.footer-info a:hover {
    color: var(--color-primary);
}

.footer-legal {
    display: flex;
    gap: var(--spacing-md);
}

.footer-legal a {
    font-size: 0.875rem;
    color: var(--color-text-light);
}

.footer-legal a:hover {
    color: var(--color-primary);
}

/* ========================================
   响应式设计
   ======================================== */
@media (max-width: 1024px) {
    .news-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .news-card.featured {
        grid-column: span 1;
    }
    
    .models-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background-color: var(--color-bg);
        flex-direction: column;
        padding: var(--spacing-md);
        border-bottom: 1px solid var(--color-border);
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .mobile-menu-btn.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    
    .mobile-menu-btn.active span:nth-child(2) {
        opacity: 0;
    }
    
    .mobile-menu-btn.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
    
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content {
        max-width: 100%;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .hero-buttons {
        justify-content: center;
        flex-wrap: wrap;
    }
    
    .hero-visual {
        order: -1;
    }
    
    .hero-graphic {
        width: 280px;
        height: 280px;
    }
    
    .news-grid {
        grid-template-columns: 1fr;
    }
    
    .models-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .footer-bottom {
        flex-direction: column;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .section-title {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 100px 0 60px;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .btn {
        padding: 0.625rem 1.5rem;
        font-size: 0.95rem;
    }
}