/* 全局重置+核心配色（活力蓝+活力橙+浅灰）+ SEO基础优化 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "Roboto", "Microsoft YaHei", sans-serif;
    scroll-behavior: smooth;
}

:root {
    --primary: #0066CC;    /* 主色-活力蓝（科技、专业） */
    --accent: #FF7A00;     /* 强调色-活力橙（运动、活力） */
    --light: #F8F9FA;      /* 浅灰背景（清爽、科技） */
    --gray: #6C757D;       /* 中性灰文本 */
    --dark-gray: #212529;  /* 深灰文本 */
    --shadow: 0 4px 15px rgba(0, 102, 204, 0.1); /* 科技风阴影 */
    --hover-shadow: 0 8px 25px rgba(0, 102, 204, 0.18); /* 悬浮增强阴影 */
    --gradient: linear-gradient(135deg, #0066CC, #0088FF); /* 蓝调科技渐变 */
    --orange-gradient: linear-gradient(135deg, #FF7A00, #FF9933); /* 橙调活力渐变 */
}

body {
    background-color: var(--light);
    color: var(--dark-gray);
    line-height: 1.7;
    overflow-x: hidden;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* 通用容器（科技风宽边距+不对称布局）+ SEO语义化 */
.container {
    width: 92%;
    max-width: 1500px;
    margin: 0 auto;
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

ul {
    list-style: none;
}

/* 架构差异化：PC端侧边固定导航（区别于滚动吸顶/折叠导航） */
.sidebar-nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 260px;
    height: 100vh;
    background: var(--gradient);
    color: #FFFFFF;
    padding: 40px 20px;
    box-shadow: var(--shadow);
    z-index: 999;
    overflow-y: auto;
}

.logo {
    font-size: 30px;
    font-weight: 700;
    color: #FFFFFF;
    margin-bottom: 60px;
    text-align: center;
    letter-spacing: 2px;
}

.logo span {
    color: var(--accent);
}

.nav-menu {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.nav-menu li a {
    color: rgba(255, 255, 255, 0.9);
    font-size: 18px;
    font-weight: 500;
    padding: 10px 15px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav-menu li a.active {
    background-color: rgba(255, 255, 255, 0.2);
    color: var(--accent);
}

.nav-menu li a:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: #FFFFFF;
}

/* 移动端架构差异化：顶部折叠导航（区别于侧滑导航） */
.mobile-header {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: var(--gradient);
    padding: 15px 20px;
    z-index: 999;
}

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

.mobile-logo {
    font-size: 24px;
    color: #FFFFFF;
    font-weight: 700;
}

.mobile-logo span {
    color: var(--accent);
}

.mobile-nav-toggle {
    color: #FFFFFF;
    font-size: 24px;
    cursor: pointer;
}

.mobile-nav-menu {
    position: fixed;
    top: 70px;
    left: 0;
    width: 100%;
    background-color: var(--primary);
    flex-direction: column;
    padding: 20px;
    display: none;
}

.mobile-nav-menu.active {
    display: flex;
}

.mobile-nav-menu li {
    margin-bottom: 20px;
}

.mobile-nav-menu li a {
    color: #FFFFFF;
    font-size: 16px;
}

/* 主内容区（适配侧边导航） */
.main-content {
    margin-left: 260px;
    flex: 1;
}

/* Banner区域（差异化：科技感全屏+不对称布局） */
.banner {
    height: 100vh;
    background: url("https://tse-mm.bing.com/th?q=Bsports 必一中国 科技运动装备 全屏场景") center/cover no-repeat;
    position: relative;
    display: flex;
    align-items: center;
    padding-left: 80px;
}

.banner::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to right, rgba(0, 102, 204, 0.8), rgba(0, 102, 204, 0.4));
}

.banner-content {
    position: relative;
    z-index: 2;
    max-width: 700px;
}

.banner-content h1 {
    font-size: 52px;
    color: #FFFFFF;
    margin-bottom: 25px;
    line-height: 1.2;
}

.banner-content h1 span {
    color: var(--accent);
}

.banner-content p {
    font-size: 20px;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: 40px;
}

.banner-btn {
    display: inline-block;
    padding: 16px 45px;
    background: var(--orange-gradient);
    color: #FFFFFF;
    border-radius: 8px;
    font-weight: 600;
    font-size: 18px;
    transition: all 0.3s ease;
    box-shadow: var(--shadow);
}

.banner-btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--hover-shadow);
}

/* 核心模块（差异化：科技风卡片+不对称网格） */
.section {
    padding: 100px 0;
    position: relative;
}

.section:nth-child(even) {
    background-color: #FFFFFF;
}

.section-title {
    font-size: 36px;
    color: var(--primary);
    margin-bottom: 50px;
    position: relative;
    padding-left: 20px;
    border-left: 5px solid var(--accent);
}

/* 中国本土化科技优势（差异化文案+科技卡片） */
.advantage-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(380px, 1fr));
    gap: 35px;
    margin-top: 30px;
}

.advantage-card {
    background-color: var(--light);
    padding: 45px 35px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    border-left: 4px solid var(--accent);
    transition: all 0.4s ease;
}

.advantage-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--hover-shadow);
}

.advantage-card h3 {
    color: var(--primary);
    font-size: 24px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 15px;
}

.advantage-card h3 i {
    color: var(--accent);
    font-size: 30px;
}

.advantage-card p {
    color: var(--gray);
    font-size: 16px;
    line-height: 1.8;
}

/* 产品中心（差异化：科技感场景卡片+中国场景分类） */
.product-filter {
    display: flex;
    gap: 15px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.product-filter-btn {
    padding: 10px 25px;
    background-color: var(--light);
    border: none;
    border-radius: 6px;
    font-size: 16px;
    font-weight: 600;
    color: var(--primary);
    cursor: pointer;
    transition: all 0.3s ease;
}

.product-filter-btn.active {
    background: var(--gradient);
    color: #FFFFFF;
}

.product-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 30px;
}

.product-card {
    background-color: #FFFFFF;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: all 0.4s ease;
}

.product-card:hover {
    box-shadow: var(--hover-shadow);
}

.product-card img {
    width: 100%;
    height: 240px;
    object-fit: cover;
    transition: all 0.4s ease;
}

.product-card:hover img {
    transform: scale(1.05);
}

.product-card .product-info {
    padding: 30px;
}

.product-card .product-info h3 {
    color: var(--primary);
    font-size: 22px;
    margin-bottom: 15px;
}

.product-card .product-info p {
    color: var(--gray);
    font-size: 16px;
    line-height: 1.7;
}

/* 新闻资讯（差异化：科技风列表+橙色时间戳） */
.news-list {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.news-item {
    display: grid;
    grid-template-columns: 2fr 5fr;
    gap: 25px;
    background-color: #FFFFFF;
    padding: 25px;
    border-radius: 10px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.news-item:hover {
    box-shadow: var(--hover-shadow);
}

.news-item-img {
    width: 100%;
    height: 180px;
    border-radius: 8px;
    overflow: hidden;
}

.news-item-img img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.news-item-content {
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.news-item-content .news-date {
    color: var(--accent);
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 8px;
}

.news-item-content .news-title {
    color: var(--primary);
    font-size: 20px;
    margin-bottom: 12px;
}

.news-item-content .news-desc {
    color: var(--gray);
    font-size: 16px;
    line-height: 1.7;
}

/* 案例展示（差异化：全屏案例+科技渐变叠加） */
.case-list {
    display: flex;
    flex-direction: column;
    gap: 40px;
}

.case-item {
    height: 480px;
    border-radius: 15px;
    overflow: hidden;
    position: relative;
    box-shadow: var(--shadow);
}

.case-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: all 0.5s ease;
}

.case-item:hover img {
    transform: scale(1.08);
}

.case-item .case-info {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 40px;
    background: linear-gradient(to top, var(--primary), transparent);
    color: #FFFFFF;
}

.case-item .case-info h3 {
    font-size: 26px;
    margin-bottom: 15px;
    color: var(--accent);
}

.case-item .case-info p {
    font-size: 16px;
    line-height: 1.8;
    opacity: 0.9;
    max-width: 900px;
}

/* 联系我们（差异化：中国区域化布局+科技表单） */
.contact-wrap {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.contact-info {
    background: var(--gradient);
    color: #FFFFFF;
    padding: 45px;
    border-radius: 12px;
}

.contact-info h3 {
    font-size: 26px;
    margin-bottom: 35px;
    color: #FFFFFF;
}

.contact-region {
    margin-bottom: 25px;
}

.contact-region h4 {
    font-size: 20px;
    margin-bottom: 12px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    padding-bottom: 8px;
}

.contact-region p {
    font-size: 16px;
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.contact-form form {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.contact-form input, .contact-form textarea, .contact-form select {
    padding: 16px;
    border: 1px solid #E0E0E0;
    border-radius: 8px;
    font-size: 16px;
    color: var(--dark-gray);
    background-color: var(--light);
    transition: all 0.3s ease;
}

.contact-form input:focus, .contact-form textarea:focus, .contact-form select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(255, 122, 0, 0.1);
}

.contact-form button {
    padding: 16px;
    background: var(--orange-gradient);
    color: #FFFFFF;
    border: none;
    border-radius: 8px;
    font-size: 18px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
}

.contact-form button:hover {
    transform: translateY(-3px);
    box-shadow: var(--hover-shadow);
}

/* 底部（差异化：科技风+中国元素） */
.footer {
    background-color: var(--primary);
    color: #FFFFFF;
    padding: 60px 0 30px;
    margin-left: 260px;
}

.footer-top {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-logo {
    font-size: 28px;
    font-weight: 700;
    color: #FFFFFF;
    margin-bottom: 20px;
}

.footer-logo span {
    color: var(--accent);
}

.footer-desc {
    color: rgba(255, 255, 255, 0.7);
    font-size: 16px;
    line-height: 1.8;
}

.footer-links h4 {
    font-size: 20px;
    margin-bottom: 20px;
    color: var(--accent);
}

.footer-links ul li {
    margin-bottom: 12px;
}

.footer-links ul li a {
    color: rgba(255, 255, 255, 0.7);
    transition: all 0.3s ease;
}

.footer-links ul li a:hover {
    color: var(--accent);
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 14px;
    color: rgba(255, 255, 255, 0.7);
}

/* 响应式适配（差异化：移动端重构为顶部导航） */
@media (max-width: 1200px) {
    .sidebar-nav {
        display: none;
    }
    .main-content, .footer {
        margin-left: 0;
    }
    .banner {
        padding-left: 40px;
    }
    .contact-wrap {
        grid-template-columns: 1fr;
    }
    .news-item {
        grid-template-columns: 1fr;
    }
    .news-item-img {
        height: 220px;
    }
}

@media (max-width: 992px) {
    .mobile-header {
        display: block;
    }
    .banner-content h1 {
        font-size: 40px;
    }
    .section-title {
        font-size: 30px;
    }
    .case-item {
        height: 400px;
    }
}

@media (max-width: 576px) {
    .banner {
        padding-left: 20px;
        height: 80vh;
    }
    .banner-content h1 {
        font-size: 30px;
    }
    .banner-content p {
        font-size: 16px;
    }
    .section {
        padding: 70px 0;
    }
    .advantage-grid, .product-grid {
        grid-template-columns: 1fr;
    }
    .case-item {
        height: 320px;
    }
    .case-item .case-info {
        padding: 20px;
    }
    .contact-info {
        padding: 30px;
    }
}