/* 全局样式 Global Styles */
:root {
    --primary-color: #00f5d4;
    --secondary-color: #1b9aaa;
    --text-color: #f5f5f5;
    --bg-color: #0f0f0f;
    --section-bg: #1a1a1a;
    --spacing: 1rem;
}

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

body {
    font-family: 'Arial', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* 头部样式 Header Styles */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(15, 15, 15, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 0;
}

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

.logo {
    font-size: 1.8rem;
    font-weight: bold;
    color: var(--primary-color);
    text-transform: uppercase;
    letter-spacing: 2px;
}

.language-selector {
    display: flex;
    list-style: none;
    gap: 1rem;
}

.lang-btn {
    background: none;
    border: none;
    color: #888;
    cursor: pointer;
    font-size: 0.9rem;
    padding: 0.3rem 0.8rem;
    border-radius: 4px;
    transition: all 0.3s ease;
}

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

.lang-btn.active {
    background-color: var(--primary-color);
    color: #000;
}

/* 语言显示控制 Language Display Control */
[class*="lang-"] {
    display: none;
}

.lang-en {
    display: block;
}

/* 英语按钮默认激活 English button active by default */
html[lang="en"] .lang-en,
html[lang="zh"] .lang-zh,
html[lang="ja"] .lang-ja,
html[lang="ko"] .lang-ko,
html[lang="es"] .lang-es {
    display: block;
}

/* 主区域样式 Hero Section */
#hero {
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    min-height: 100vh;
    background: linear-gradient(rgba(0,0,0,0.7), rgba(0,0,0,0.8)), url('videos/feature.mp4');
    background-size: cover;
    background-position: center;
    position: relative;
    overflow: hidden;
}

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

#hero .container {
    position: relative;
    z-index: 1;
}

#hero h1 {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1rem;
    color: var(--primary-color);
    text-shadow: 0 0 20px rgba(0, 245, 212, 0.8);
    letter-spacing: 4px;
}

.hero-subtitle p {
    font-size: 1.5rem;
    max-width: 700px;
    margin: 0 auto;
}

/* 内容区域 Content Sections */
section {
    padding: 7rem 0 5rem;
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--primary-color);
    position: relative;
    display: inline-block;
    left: 50%;
    transform: translateX(-50%);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 60%;
    height: 3px;
    background: linear-gradient(90deg, transparent, var(--primary-color), transparent);
}

.section-description {
    max-width: 800px;
    margin: 0 auto 4rem auto;
    text-align: center;
    font-size: 1.1rem;
    line-height: 1.8;
}

/* 视频网格 Video Grid - 采用不规则排版 */
.video-grid {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    grid-auto-rows: minmax(160px, auto);
    gap: 1.5rem;
    margin-bottom: 2rem;
    padding: 0 1rem;
    position: relative;
}

/* 不规则视频项大小 */
.video-item {
    position: relative;
    overflow: hidden;
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    grid-column: span 4;
    grid-row: span 1;
    min-height: 200px;
    transform: translateY(0);
    opacity: 0.95;
}

/* 特殊大小的视频项 */
.video-item:nth-child(1) {
    grid-column: span 5;
    grid-row: span 2;
    min-height: 320px;
}

.video-item:nth-child(2) {
    grid-column: span 7;
    grid-row: span 1;
}

.video-item:nth-child(4) {
    grid-column: span 6;
    grid-row: span 2;
    min-height: 300px;
}

.video-item:nth-child(5) {
    grid-column: span 6;
    grid-row: span 1;
}

.video-item:nth-child(8) {
    grid-column: span 8;
    grid-row: span 1;
}

.video-item:nth-child(9) {
    grid-column: span 4;
    grid-row: span 2;
    min-height: 280px;
}

/* 人物中心视频布局特殊处理 */
#human-centric .video-item:nth-child(1) {
    grid-column: span 8;
    grid-row: span 2;
}

#human-centric .video-item:nth-child(2) {
    grid-column: span 4;
    grid-row: span 1;
}

#human-centric .video-item:nth-child(3) {
    grid-column: span 4;
    grid-row: span 1;
}

/* 参考视频特殊布局 */
#generate-by-references .video-item:nth-child(3) {
    grid-column: span 8;
    grid-row: span 1;
}

#generate-by-references .video-item:nth-child(4) {
    grid-column: span 4;
    grid-row: span 1;
}

.video-item:hover {
    transform: translateY(-8px) scale(1.03);
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.6), 0 0 20px rgba(0, 245, 212, 0.2);
    z-index: 10;
    opacity: 1;
}

.video-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, rgba(0,0,0,0.1), rgba(0,0,0,0.4));
    z-index: 1;
    opacity: 0.5;
    transition: opacity 0.3s ease;
}

.video-item:hover::before {
    opacity: 0;
}

.video-item video {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.5s ease;
}

.video-item:hover video {
    transform: scale(1.05);
}

/* 各部分背景颜色 Section Background Colors */
#introducing, #human-centric {
    background-color: var(--section-bg);
}

/* FAQ 栏目 FAQ Columns */
.faq-columns {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 2rem;
}

.faq-column h3 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
}

.faq-item {
    margin-bottom: 1.5rem;
}

.faq-question {
    font-weight: bold;
    margin-bottom: 0.5rem;
}

/* 页脚 Footer */
footer {
    background-color: #000;
    padding: 2rem 0;
    text-align: center;
}

.footer-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

/* 响应式设计 Responsive Design */
@media (max-width: 992px) {
    .section-title {
        font-size: 2rem;
    }
    
    #hero h1 {
        font-size: 3rem;
    }
    
    .hero-subtitle p {
        font-size: 1.2rem;
    }
    
    .video-grid {
        grid-template-columns: repeat(8, 1fr);
    }
    
    .video-item {
        grid-column: span 4;
    }
    
    .video-item:nth-child(1) {
        grid-column: span 5;
    }
    
    .video-item:nth-child(3) {
        grid-column: span 3;
    }
}

@media (max-width: 768px) {
    .video-grid {
        grid-template-columns: repeat(6, 1fr);
    }
    
    .video-item,
    .video-item:nth-child(n) {
        grid-column: span 3;
        grid-row: span 1;
    }
    
    .video-item:nth-child(1),
    .video-item:nth-child(4),
    #human-centric .video-item:nth-child(1) {
        grid-column: span 6;
        grid-row: span 1;
    }
    
    .section-title {
        font-size: 1.8rem;
    }
    
    #hero h1 {
        font-size: 2.5rem;
    }
    
    .hero-subtitle p {
        font-size: 1.1rem;
    }
}

@media (max-width: 576px) {
    .container {
        padding: 0 1.5rem;
    }
    
    section {
        padding: 4rem 0;
    }
    
    .video-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.8rem;
    }
    
    .video-item,
    .video-item:nth-child(n) {
        grid-column: span 2;
    }
    
    .faq-columns {
        grid-template-columns: 1fr;
    }
    
    #hero h1 {
        font-size: 2rem;
    }
    
    .hero-subtitle p {
        font-size: 1rem;
    }
    
    .language-selector {
        gap: 0.5rem;
    }
    
    .lang-btn {
        padding: 0.2rem 0.5rem;
        font-size: 0.8rem;
    }
}

/* 为不同部分设置特殊布局 */
#introducing .video-grid {
    grid-auto-flow: dense;
}

#introducing .video-item:nth-child(3) {
    grid-column: span 6;
    grid-row: span 1;
}

#introducing .video-item:nth-child(6) {
    grid-column: span 8;
    grid-row: span 1;
}

#introducing .video-item:nth-child(7) {
    grid-column: span 4;
    grid-row: span 2;
}

#generate-from-images .video-grid {
    grid-template-rows: repeat(3, minmax(200px, auto));
}

#generate-from-images .video-item:nth-child(1) {
    grid-column: span 8;
    grid-row: span 2;
    min-height: 360px;
}

#generate-from-images .video-item:nth-child(2) {
    grid-column: span 4;
    grid-row: span 1;
}

#generate-from-images .video-item:nth-child(3) {
    grid-column: 9 / span 4;
    grid-row: 2 / span 1;
}

#generate-from-images .video-item:nth-child(4) {
    grid-column: 1 / span 5;
    grid-row: 3 / span 1;
}

#generate-from-images .video-item:nth-child(5) {
    grid-column: 6 / span 3;
    grid-row: 3 / span 1;
}

#generate-from-images .video-item:nth-child(6) {
    grid-column: 9 / span 4;
    grid-row: 3 / span 1;
}

@media (max-width: 768px) {
    #introducing .video-item:nth-child(n),
    #generate-from-images .video-item:nth-child(n),
    #generate-by-references .video-item:nth-child(n),
    #human-centric .video-item:nth-child(n) {
        grid-column: span 3;
        grid-row: span 1;
        min-height: 180px;
    }
    
    #introducing .video-item:nth-child(1),
    #generate-from-images .video-item:nth-child(1),
    #human-centric .video-item:nth-child(1) {
        grid-column: span 6;
        min-height: 240px;
    }
}

/* 视频项动画效果 */
@keyframes fadeUp {
    0% {
        opacity: 0;
        transform: translateY(20px);
    }
    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

#introducing .video-item:nth-child(1) { animation: fadeUp 0.6s ease-out 0.1s both; }
#introducing .video-item:nth-child(2) { animation: fadeUp 0.6s ease-out 0.2s both; }
#introducing .video-item:nth-child(3) { animation: fadeUp 0.6s ease-out 0.3s both; }
#introducing .video-item:nth-child(4) { animation: fadeUp 0.6s ease-out 0.4s both; }
#introducing .video-item:nth-child(5) { animation: fadeUp 0.6s ease-out 0.5s both; }
#introducing .video-item:nth-child(6) { animation: fadeUp 0.6s ease-out 0.6s both; }
#introducing .video-item:nth-child(7) { animation: fadeUp 0.6s ease-out 0.7s both; }
#introducing .video-item:nth-child(8) { animation: fadeUp 0.6s ease-out 0.8s both; }
#introducing .video-item:nth-child(9) { animation: fadeUp 0.6s ease-out 0.9s both; }

#generate-from-images .video-item:nth-child(1) { animation: fadeUp 0.6s ease-out 0.1s both; }
#generate-from-images .video-item:nth-child(2) { animation: fadeUp 0.6s ease-out 0.2s both; }
#generate-from-images .video-item:nth-child(3) { animation: fadeUp 0.6s ease-out 0.3s both; }
#generate-from-images .video-item:nth-child(4) { animation: fadeUp 0.6s ease-out 0.4s both; }
#generate-from-images .video-item:nth-child(5) { animation: fadeUp 0.6s ease-out 0.5s both; }
#generate-from-images .video-item:nth-child(6) { animation: fadeUp 0.6s ease-out 0.6s both; }