* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Roboto, system-ui, sans-serif;
}

body {
    background: #f9fafc;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    color: #1e293b;
}

/* 导航栏 */
.navbar {
    background: #ffffff;
    padding: 1rem 5%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: 0 4px 12px rgba(0,0,0,0.03);
    border-bottom: 2px solid #e9edf4;
    flex-wrap: wrap;
}

.logo {
    font-size: 1.6rem;
    font-weight: 600;
    color: #0f3b5e;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    text-decoration: none;
    font-weight: 500;
    color: #334155;
    padding: 0.5rem 0.25rem;
    transition: 0.2s;
    border-bottom: 2px solid transparent;
}

.nav-links a:hover,
.nav-links a.active {
    color: #0277bd;
    border-bottom-color: #0277bd;
}

.cart-icon {
    font-size: 1.7rem;
    cursor: default;
    opacity: 0.7;
}

/* 主内容区 */
main {
    flex: 1;
    max-width: 1300px;
    width: 90%;
    margin: 2rem auto;
}

/* 首页卡片网格 默认由index内style强制两列，此为基础 */
.category-grid {
    display: grid;
    gap: 2rem;
    margin-bottom: 3rem;
}

.card {
    background: white;
    border-radius: 24px;
    padding: 1.5rem 1.5rem 2rem;
    box-shadow: 0 12px 24px -8px rgba(0, 32, 64, 0.1);
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
    cursor: pointer;
    border: 1px solid #edf2f9;
}

.card:hover {
    transform: translateY(-6px);
    box-shadow: 0 24px 32px -10px rgba(0,79,158,0.2);
}

.card h2 {
    font-size: 1.7rem;
    font-weight: 600;
    margin: 1rem 0 0.5rem;
}

.card p {
    color: #475569;
    margin-bottom: 1.5rem;
}

.tag {
    background: #e1f0fa;
    padding: 0.4rem 1.2rem;
    border-radius: 40px;
    color: #0369a1;
    font-weight: 500;
    font-size: 0.95rem;
}

.info-section {
    background: white;
    padding: 2rem;
    border-radius: 24px;
    line-height: 1.8;
    border: 1px solid #e9edf4;
    margin-top: 2rem;
}

/* 页面标题 (子页面) */
.page-title {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #0b3a5a;
    border-left: 8px solid #0284c7;
    padding-left: 1.2rem;
}

.page-subtitle {
    color: #4a627a;
    margin-bottom: 2.5rem;
    font-size: 1.2rem;
    margin-left: 2rem;
}

/* 产品网格 (三种机器人卡片) */
.product-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin: 2.5rem 0;
}

.product-card {
    background: white;
    border-radius: 28px;
    padding: 1.8rem 1.5rem 2rem;
    box-shadow: 0 15px 30px rgba(0, 30, 60, 0.07);
    transition: 0.25s ease;
    display: flex;
    flex-direction: column;
    border: 1px solid #e2eaf2;
}

.product-card:hover {
    box-shadow: 0 24px 40px -12px #0284c755;
}

/* 注意：图片样式已由各页面内嵌 style 统一为 1:1 居中，此基础样式保留宽高自适应 */
.product-img {
    margin-bottom: 1.2rem;
    border-radius: 20px;
    overflow: hidden;
}

.product-card h3 {
    font-size: 1.8rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.product-card p {
    color: #475569;
    flex: 1;
    margin-bottom: 1.2rem;
}

.price {
    font-size: 2rem;
    font-weight: 700;
    color: #1b4f6e;
    margin: 0.5rem 0 1.2rem;
}

.buy-btn {
    background: #0277bd;
    color: white;
    border: none;
    padding: 1rem 0;
    font-size: 1.3rem;
    font-weight: 600;
    border-radius: 50px;
    cursor: pointer;
    transition: 0.15s;
    box-shadow: 0 8px 14px -7px #025b91;
    margin-top: 0.2rem;
}

.buy-btn:hover {
    background: #015f9b;
    transform: scale(1.02);
}

.demo-hint {
    background: #e6f2fc;
    padding: 0.8rem 1.5rem;
    border-radius: 60px;
    display: inline-block;
    margin: 1rem 0 2rem;
    color: #0369a1;
    font-weight: 500;
}

/* 页脚 */
footer {
    text-align: center;
    padding: 2rem;
    background: #ffffff;
    border-top: 1px solid #dde3ed;
    color: #4b6584;
    margin-top: 2rem;
}

/* 移动端适应 */
@media (max-width: 650px) {
    .navbar {
        flex-direction: column;
        gap: 0.8rem;
    }
    .nav-links {
        gap: 1rem;
        flex-wrap: wrap;
        justify-content: center;
    }
    .page-title {
        font-size: 2rem;
    }
    .product-grid {
        grid-template-columns: 1fr;
    }
}