/* ==================================================
   全局重置 & 基础样式
   ================================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, Helvetica, sans-serif;
}

html {
    scroll-behavior: smooth;
}

body {
    background: #f8fafc;
    color: #333;
    line-height: 1.6;
    padding-top: 60px; /* 为固定导航留出空间 */
}

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

img {
    display: block;
}

/* 容器：居中、宽度自适应 */
.container {
    width: 94%;
    max-width: 1200px;
    margin: 0 auto;
}

/* 公用标题样式（带装饰线） */
.section-title {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 14px;
    margin-bottom: 40px;
}

.section-title .line {
    width: 80px;
    height: 1px;
    background: #999;
}

.section-title h2 {
    font-size: 28px;
    font-weight: 600;
    color: #222;
    letter-spacing: 0.5px;
}

/* ==================================================
   顶部导航栏（固定）
   ================================================== */
.header {
    width: 100%;
    height: 60px;
    background: #000;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 9999;
}

.header-wrap {
    width: 94%;
    max-width: 1200px;
    height: 100%;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Logo 链接 */
.logo-link {
    display: flex;
    align-items: center;
    text-decoration: none;
}

.logo-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

/* ★★★ Logo 图片样式：固定大小，自适应内容 ★★★ */
.logo-img {
    width: 36px;      /* 固定宽度 */
    height: 36px;     /* 固定高度 */
    object-fit: contain; /* 保持比例，不拉伸变形 */
    display: block;
    flex-shrink: 0;   /* 防止缩放时被压缩 */
}

.logo-text {
    color: #fff;
    font-size: 18px;
    font-weight: 600;
    letter-spacing: 1px;
}

/* 桌面端导航 */
.nav-pc {
    display: flex;
    gap: 34px;
}

.nav-pc a {
    color: #ccc;
    font-size: 14px;
}

.nav-pc a:hover,
.nav-pc a.active {
    color: #63a4ff; /* 当前页面高亮 */
}

/* 移动端菜单按钮（默认隐藏） */
.menu-btn {
    display: none;
    color: #fff;
    font-size: 24px;
    cursor: pointer;
}

/* 移动端下拉菜单（默认隐藏） */
.nav-mobile {
    display: none;
    background: #111;
    flex-direction: column;
    padding: 20px 3%;
    gap: 16px;
}

.nav-mobile.show {
    display: flex;
}

.nav-mobile a {
    color: #ddd;
    font-size: 16px;
}

.nav-mobile a.active {
    color: #63a4ff;
}

/* ==================================================
   About 页面主区域
   ================================================== */
.about-page {
    padding: 60px 0 50px;
    background: #f8fafc;
}

/* ---- 公司概况（双栏布局） ---- */
.about-intro {
    display: flex;
    gap: 40px;
    align-items: center;
    background: #fff;
    border-radius: 24px;
    padding: 44px 48px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.04);
    margin-bottom: 50px;
}

.about-intro-text {
    flex: 2;
}

.about-intro-text h3 {
    font-size: 30px;
    font-weight: 700;
    color: #222;
    margin-bottom: 4px;
}

.about-intro-text h3 span {
    color: #63a4ff;
    font-weight: 400;
    font-size: 22px;
}

.about-location {
    font-size: 14px;
    color: #666;
    margin-bottom: 14px;
}

.about-location i {
    color: #63a4ff;
    margin-right: 8px;
}

/* 业务范围标签 */
.about-biz {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 14px;
    margin-bottom: 18px;
}

.about-biz span {
    background: #f0f4ff;
    padding: 4px 16px;
    border-radius: 30px;
    font-size: 13px;
    color: #1a1e25;
    display: inline-flex;
    align-items: center;
    gap: 6px;
}

.about-biz span i {
    color: #63a4ff;
}

/* 公司描述 */
.about-desc {
    font-size: 15px;
    color: #444;
    line-height: 1.8;
}

.about-desc strong {
    color: #1a1e25;
}

/* 右侧图片占位 */
.about-intro-image {
    flex: 1;
    min-width: 160px;
}

.about-image-placeholder {
    background: linear-gradient(145deg, #eef2f7, #dde3ec);
    border-radius: 18px;
    aspect-ratio: 4/3;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: #6a7a8a;
    font-size: 18px;
    transition: all 0.3s ease;
}

.about-image-placeholder i {
    font-size: 52px;
    margin-bottom: 8px;
    color: #63a4ff;
}

/* ---- 技术实力卡片网格 ---- */
.tech-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    margin-bottom: 40px;
}

.tech-card {
    background: #fff;
    padding: 26px 18px;
    border-radius: 18px;
    text-align: center;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
    transition: all 0.3s ease;
}

.tech-card:hover {
    transform: translateY(-6px);
    box-shadow: 0 12px 36px rgba(0, 0, 0, 0.07);
}

.tech-icon {
    width: 60px;
    height: 60px;
    background: #ebf3ff;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 14px;
    color: #63a4ff;
    font-size: 28px;
}

.tech-card h4 {
    font-size: 17px;
    margin-bottom: 6px;
    color: #222;
}

.tech-card p {
    font-size: 13px;
    color: #666;
    line-height: 1.6;
}

/* ---- 认证 + 核心优势（双栏） ---- */
.about-cert-advantages {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 30px;
    background: #fff;
    border-radius: 24px;
    padding: 40px 44px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.04);
    margin: 30px 0 44px;
}

.about-cert {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.cert-badge {
    display: flex;
    align-items: center;
    gap: 16px;
}

.cert-badge i {
    font-size: 40px;
    color: #63a4ff;
}

.cert-badge h4 {
    font-size: 20px;
    color: #222;
    margin-bottom: 2px;
}

.cert-badge p {
    font-size: 13px;
    color: #666;
}

.cert-desc {
    font-size: 14px;
    color: #444;
    line-height: 1.7;
    padding-left: 4px;
}

.about-advantages h4 {
    font-size: 20px;
    color: #222;
    margin-bottom: 14px;
}

.advantage-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.advantage-list li {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 15px;
    color: #444;
}

.advantage-list li i {
    color: #63a4ff;
    width: 24px;
    text-align: center;
    font-size: 18px;
}

/* ---- 联系方式卡片 ---- */
.contact-cards {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    margin-top: 20px;
}

.contact-card {
    background: #fff;
    padding: 22px 26px;
    border-radius: 18px;
    display: flex;
    align-items: center;
    gap: 20px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
    transition: all 0.3s ease;
}

.contact-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.06);
}

.contact-card i {
    font-size: 30px;
    color: #63a4ff;
    width: 44px;
    text-align: center;
}

.contact-card h4 {
    font-size: 13px;
    color: #999;
    font-weight: 400;
    margin-bottom: 2px;
}

.contact-card p {
    font-size: 16px;
    font-weight: 500;
    color: #222;
}

.contact-card a {
    color: #222;
}

.contact-card a:hover {
    color: #63a4ff;
}

/* ==================================================
   页脚 Footer
   ================================================== */
.footer {
    background: #0a0a0a;
    color: #aaa;
    padding: 40px 0 30px;
    font-size: 14px;
    border-top: 1px solid rgba(255, 255, 255, 0.04);
    margin-top: 30px;
}

.footer-wrap {
    display: flex;
    align-items: flex-start;
    gap: 40px;
}

.footer-left {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-right {
    display: flex;
    align-items: flex-end;
    justify-content: flex-end;
    flex-shrink: 0;
}

.footer-brand h3 {
    color: #fff;
    font-size: 22px;
    font-weight: 700;
    letter-spacing: 0.5px;
}

.footer-brand h3 span {
    color: #63a4ff;
    font-weight: 400;
    font-size: 16px;
}

.footer-info {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.footer-info p {
    font-size: 13px;
    color: #999;
    display: flex;
    align-items: center;
    gap: 10px;
    line-height: 1.6;
}

.footer-info p i {
    color: #63a4ff;
    width: 18px;
    font-size: 14px;
    text-align: center;
    flex-shrink: 0;
}

.footer-social {
    display: flex;
    gap: 16px;
    margin: 6px 0;
}

.footer-social a {
    width: 42px;
    height: 42px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.06);
    color: #ccc;
    font-size: 18px;
    transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.footer-social a:hover {
    transform: scale(1.15);
    background: #63a4ff;
    color: #fff;
    box-shadow: 0 0 12px rgba(99, 164, 255, 0.25);
}

.footer-copyright {
    margin-top: 6px;
    padding-top: 12px;
    border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer-copyright p {
    font-size: 12px;
    color: #666;
}

/* 返回顶部按钮（默认隐藏，滚动后显示） */
.back-to-top {
    width: 52px;
    height: 52px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.12);
    background: rgba(255, 255, 255, 0.04);
    color: #ccc;
    font-size: 20px;
    cursor: pointer;
    transition: all 0.35s cubic-bezier(0.16, 1, 0.3, 1);
    display: flex;
    align-items: center;
    justify-content: center;
    backdrop-filter: blur(4px);
    opacity: 0;          /* 初始不可见 */
    pointer-events: none; /* 不可点击 */
}

.back-to-top:hover {
    background: #63a4ff;
    border-color: #63a4ff;
    color: #fff;
    transform: translateY(-4px) scale(1.04);
    box-shadow: 0 8px 28px rgba(99, 164, 255, 0.28);
}

/* ==================================================
   响应式布局
   ================================================== */

/* 平板及以下 */
@media (max-width: 992px) {
    /* 隐藏桌面导航，显示菜单按钮 */
    .nav-pc {
        display: none;
    }
    .menu-btn {
        display: block;
    }

    /* 公司概况改为上下排列 */
    .about-intro {
        flex-direction: column;
        padding: 32px 28px;
    }
    .about-intro-image {
        width: 100%;
    }

    /* 技术实力卡片改为2列 */
    .tech-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    /* 认证+优势改为单列 */
    .about-cert-advantages {
        grid-template-columns: 1fr;
        padding: 32px 28px;
    }

    /* 联系方式改为单列 */
    .contact-cards {
        grid-template-columns: 1fr;
    }

    /* 页脚调整为上下排列 */
    .footer-wrap {
        flex-direction: column;
        gap: 24px;
    }
    .footer-right {
        align-items: center;
        justify-content: center;
    }
}

/* 手机 */
@media (max-width: 768px) {
    .about-intro {
        padding: 24px 18px;
    }
    .about-intro-text h3 {
        font-size: 24px;
    }
    .tech-grid {
        grid-template-columns: 1fr; /* 改为单列 */
    }
    .footer-brand h3 {
        font-size: 20px;
    }
    .footer-info p {
        font-size: 12px;
        align-items: flex-start;
    }
    .footer-social {
        justify-content: center;
    }
    .footer-social a {
        width: 36px;
        height: 36px;
        font-size: 16px;
    }
}

/* 小屏手机 */
@media (max-width: 576px) {
    .section-title h2 {
        font-size: 22px;
    }
    .about-intro {
        padding: 20px 16px;
    }
    .about-intro-text h3 {
        font-size: 20px;
    }
    .about-biz span {
        font-size: 12px;
        padding: 2px 12px;
    }
    .about-desc {
        font-size: 14px;
    }
    .tech-card {
        padding: 20px 14px;
    }
    .about-cert-advantages {
        padding: 24px 18px;
    }
    .contact-card {
        padding: 18px 20px;
    }
    .footer {
        padding: 30px 0 20px;
    }
    .back-to-top {
        width: 44px;
        height: 44px;
        font-size: 16px;
    }
}