:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-main: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --gradient: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
}

/* 导航栏 */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 5%;
    background: rgba(15, 23, 42, 0.9);
    backdrop-filter: blur(10px);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 1px solid #334155;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.lang-btn {
    background: transparent;
    border: 1px solid var(--text-secondary);
    color: var(--text-main);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s;
}

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

/* Hero 区域 */
.hero {
    text-align: center;
    padding: 5rem 1rem;
    background: radial-gradient(circle at center, #1e293b 0%, #0f172a 70%);
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.hero p {
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 2rem auto;
}

/* 搜索框 */
.search-box input {
    width: 100%;
    max-width: 400px;
    padding: 1rem;
    border-radius: 12px;
    border: 1px solid #334155;
    background: var(--card-bg);
    color: white;
    outline: none;
}

.search-box input:focus {
    border-color: var(--accent);
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

/* 分类按钮 */
.categories {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    justify-content: center;
    flex-wrap: wrap;
}

.cat-btn {
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
    border: none;
    background: var(--card-bg);
    color: var(--text-secondary);
    cursor: pointer;
    transition: 0.3s;
}

.cat-btn.active, .cat-btn:hover {
    background: var(--accent);
    color: white;
}

/* 卡片网格 */
.ai-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

/* 卡片样式 */
.ai-card {
    background: var(--card-bg);
    border-radius: 16px;
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
    border: 1px solid #334155;
    display: flex;
    flex-direction: column;
}

.ai-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.5);
    border-color: var(--accent);
}

.card-img {
    width: 100%;
    height: 180px;
    object-fit: cover;
    background: #000;
}

.card-content {
    padding: 1.5rem;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.card-title {
    font-size: 1.25rem;
    font-weight: 600;
}

.card-tag {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    border-radius: 12px;
    background: rgba(59, 130, 246, 0.1);
    color: var(--accent);
}

.card-desc {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
    flex-grow: 1;
}

.card-btn {
    display: block;
    text-align: center;
    background: var(--gradient);
    color: white;
    text-decoration: none;
    padding: 0.75rem;
    border-radius: 8px;
    font-weight: 600;
    transition: opacity 0.3s;
}

.card-btn:hover {
    opacity: 0.9;
}

/* 页脚 */
footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-secondary);
    border-top: 1px solid #334155;
    margin-top: 4rem;
}

/* 移动端适配 */
@media (max-width: 768px) {
    .hero h1 { font-size: 2rem; }
    .ai-grid { grid-template-columns: 1fr; }
}