/* ====================
       1. 基础设置与变量
       ==================== */
    :root {
        --primary-color: #0069b4; /* CATL 蓝 */
        --secondary-color: #004d85;
        --text-dark: #333333;
        --text-gray: #666666;
        --text-light: #ffffff;
        --bg-light: #f9f9f9;
        --transition-speed: 0.4s;
        --card-shadow: 0 10px 30px rgba(0,0,0,0.08);
        --card-hover-shadow: 0 20px 40px rgba(0,0,0,0.15);
    }

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

    body {
        font-family: "Helvetica Neue", Helvetica, Arial, "Microsoft YaHei", sans-serif;
        color: var(--text-dark);
        line-height: 1.6;
        overflow-x: hidden;
        background-color: #fff;
    }

    ul { list-style: none; }
    a { text-decoration: none; color: inherit; }
    img { max-width: 100%; display: block; }
    
.hero {
    height: 100vh;
    width: 100%;
    background: linear-gradient(rgba(0,0,0,0.3), rgba(0,0,0,0.3)), url('/css/img/hx.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed; /* 简单的视差效果 */
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    color: white;
    padding: 0 20px;
}

.hero h1 {
    font-size: 4rem;
    margin-bottom: 20px;
    text-shadow: 0 2px 10px rgba(0,0,0,0.3);
    opacity: 0;
    transform: translateY(30px);
    animation: fadeUp 1s forwards 0.5s;
}

.hero p {
    font-size: 1.5rem;
    max-width: 800px;
    margin-bottom: 40px;
    opacity: 0;
    transform: translateY(30px);
    animation: fadeUp 1s forwards 0.8s;
}

.btn {
    padding: 15px 40px;
    border-radius: 50px;
    border: 2px solid white;
    color: white;
    font-size: 1.1rem;
    transition: all 0.3s;
    cursor: pointer;
    opacity: 0;
    animation: fadeUp 1s forwards 1.1s;
}

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

/* ====================
   4. 核心技术展示 (Grid 布局)
   ==================== */
.section {
    padding: 100px 5%;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 20px;
    color: var(--text-dark);
}

.section-subtitle {
    text-align: center;
    color: var(--text-gray);
    margin-bottom: 60px;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.tech-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--card-shadow);
    transition: all var(--transition-speed);
    position: relative;
    cursor: pointer;
    /* 初始隐藏，用于滚动动画 */
    opacity: 0;
    transform: translateY(50px);
}

.tech-card.visible {
    opacity: 1;
    transform: translateY(0);
}

.tech-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--card-hover-shadow);
}

.card-img-wrapper {
    height: 250px;
    overflow: hidden;
    position: relative;
}

.card-img-wrapper img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.6s ease;
}

.tech-card:hover .card-img-wrapper img {
    transform: scale(1.1);
}

.card-content {
    padding: 30px;
}

.card-content h3 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: var(--text-dark);
}

.card-content p {
    color: var(--text-gray);
    font-size: 0.95rem;
    margin-bottom: 20px;
}

.card-link {
    color: var(--primary-color);
    font-weight: 600;
    display: inline-flex;
    align-items: center;
}

.card-link::after {
    content: '→';
    margin-left: 8px;
    transition: transform 0.3s;
}

.tech-card:hover .card-link::after {
    transform: translateX(5px);
}

/* ====================
   5. 解决方案 Tab 切换 (交互优化)
   ==================== */
.solutions-section {
    background-color: var(--bg-light);
}

.tabs-nav {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-bottom: 50px;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 12px 30px;
    border: 1px solid #ddd;
    border-radius: 30px;
    background: transparent;
    cursor: pointer;
    font-size: 1rem;
    color: var(--text-gray);
    transition: all 0.3s;
}

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

.tab-content {
    display: none;
    animation: fadeIn 0.5s ease;
}

.tab-content.active {
    display: block;
}

/* 模拟数据表格布局 */
.data-table-container {
    background: white;
    border-radius: 12px;
    padding: 40px;
    box-shadow: var(--card-shadow);
}

.spec-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
    text-align: center;
}

.spec-item h4 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 10px;
    font-family: 'Arial', sans-serif;
}

.spec-item p {
    font-size: 0.9rem;
    color: var(--text-gray);
}

/* ====================
   6. 动画关键帧
   ==================== */
@keyframes fadeUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* 移动端适配 */
@media (max-width: 768px) {
    .hero h1 { font-size: 2.5rem; }
    .spec-grid { grid-template-columns: 1fr 1fr; gap: 40px; }
    .navbar { padding: 15px 20px; }
    .nav-links { display: none; } /* 简化处理，隐藏菜单 */
}

.cta { 
    background: #0066cc; 
    color: #fff; 
    padding: 12px 35px; 
    text-decoration: none; 
    border-radius: 30px; 
    font-weight: 600; 
    display: inline-block; 
    margin:20px auto;
    width:200px;
    display:block;
}
.cta:hover { 
    background: #004499; 
    transform: translateY(-2px); 
    transition: all 0.3s; 
}