:root {
    --primary-green: #303296;
    --dark-gray: #374151;
    --light-gray: #f3f4f6;
    --white: #ffffff;
    --text-gray: #6b7280;
    --black: #000;
    --container-max: 1400px;
}

* { margin:0; padding:0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif; line-height:1.6; color:#333; }
.container { max-width: 1400px; margin:0 auto; padding:0 10px; }

/* Header */
.header { background: var(--white); box-shadow: 0 2px 10px rgba(0,0,0,0.1); position: fixed; top:0; width:100%; z-index:1000; padding:0; }
.nav { display:flex; justify-content: space-between; align-items:center; padding:1rem 0; min-height:80px; }
.logo { height:40px; display:flex; align-items:center; }
.logo img { height:100%; width:auto; max-height:40px; }
.nav-links { display:flex; list-style:none; gap:2rem; }
.nav-links li { position:relative; }
.dropdown-menu { position:absolute; top:100%; left:0; background: var(--white); border:1px solid #e5e7eb; box-shadow:0 10px 24px rgba(0,0,0,.08); border-radius:6px; padding:8px 0; min-width:180px; display:none; z-index:1001; }
.dropdown-menu li { list-style:none; }
.dropdown-menu a { display:block; padding:10px 14px; color:#374151; text-decoration:none; white-space:nowrap; }
.dropdown-menu a:hover { background:#f3f4f6; color: var(--primary-green); }
.nav-links li:hover > .dropdown-menu { display:block; }
.nav-links a { text-decoration:none; color: var(--dark-gray); font-weight:500; transition: color .3s; display:flex; align-items:center; gap:.3rem; }
.nav-links a:hover, .nav-links a.active { color: var(--primary-green); }
.nav-actions { display:flex; align-items:center; gap:1rem; }
.search-icon { width:16px; height:16px; border:2px solid #374151; border-radius:50%; position:relative; cursor:pointer; }
.search-icon::after { content:""; position:absolute; bottom:-4px; right:-4px; width:6px; height:2px; background:#374151; transform:rotate(45deg); }

/* Mobile menu */
.mobile-menu-toggle { display:none; flex-direction:column; justify-content: space-around; width:24px; height:24px; background:transparent; border:none; cursor:pointer; padding:0; z-index:1002; }
.mobile-menu-toggle span { width:100%; height:2px; background: var(--dark-gray); transition: all .3s ease; transform-origin:center; }
.mobile-menu { position:fixed; top:0; left:-100%; width:280px; height:100vh; background: var(--white); box-shadow:2px 0 10px rgba(0,0,0,.1); transition:left .3s ease; z-index:1001; padding-top:80px; overflow-y:auto; }
.mobile-menu.active { left:0; }
.mobile-menu ul { list-style:none; }
.mobile-menu li { border-bottom:1px solid #e5e7eb; }
.mobile-menu a { display:block; padding:1rem 1.5rem; color: var(--dark-gray); text-decoration:none; font-weight:500; transition: background-color .3s; }
.mobile-menu a:hover, .mobile-menu a.active { background:#f3f4f6; color: var(--primary-green); }
.mobile-overlay { position:fixed; inset:0; background: rgba(0,0,0,.5); z-index:1000; display:none; }
.mobile-overlay.active { display:block; }

/* Hero */
.hero {
    background: url('../images/154898373842521we9f.png') center/cover no-repeat;
    color: var(--white);
    height: 600px;
    margin-top: 0;
    position: relative;
    display: flex;
    align-items: center;
}
.hero::before { content:""; position:absolute; inset:0; background: rgba(0,0,0,.35); z-index:1; }
.hero-content { position:relative; z-index:2; text-align:center; }
.hero h1 { font-size: 3rem; font-weight: 800; margin-bottom: .5rem; text-shadow: 2px 2px 4px rgba(0,0,0,.5); }
.hero-subtitle { color:#e5e7eb; }

/* Main */
.main-content { position:relative; z-index:3; margin-top:-80px; padding: 0 0 4rem 0; }

/* Separated Background Visual above grid */
.showcase-hero { position: relative; border-radius: 0; overflow: hidden; margin-bottom: 24px; }
.showcase-hero__bg { height: 120px; background: url('../images/jpg80-t4-width1920(6).webp') center/cover no-repeat; filter: contrast(1.05) brightness(.95); }
.showcase-hero__content { position: absolute; inset: 0; display: none; place-items: center; text-align: center; color: #fff; }
.showcase-hero__title { font-size: 2.4rem; font-weight: 900; text-shadow: 0 6px 28px rgba(0,0,0,.45); letter-spacing: .02em; }
.showcase-hero__subtitle { margin-top: .5rem; opacity: .9; }

/* Product Showcase Section */
.product-showcase { background: #fff; margin-bottom: 2rem; }
.showcase-header { text-align: center; margin-bottom: 2rem; }
.showcase-title { font-size: 2.2rem; font-weight: 800; color: var(--black); margin-bottom: .6rem; }
.showcase-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.showcase-item { display: flex; flex-direction: column; align-items: stretch; background:#fff; border:none; border-radius:0; padding:20px; box-shadow:0 10px 30px rgba(0,0,0,.08); transition: box-shadow .25s ease; cursor: default; }
.showcase-item:hover { box-shadow:0 12px 30px rgba(0,0,0,.12); }
.product-brand { display: none; font-size: 1.5rem; font-weight: 700; color: #16a34a; margin-bottom: 1rem; text-align: center; }
.product-image { width: 100%; height: 260px; display: flex; align-items: center; justify-content: center; margin-bottom: 16px; }
.product-image img { max-width: 100%; max-height: 100%; object-fit: contain; transition: transform .3s ease, filter .3s ease; }
.showcase-item:hover .product-image img { transform: scale(1.06); filter: brightness(1.06) contrast(1.05); }
.product-info { /*background: #f3f4f6;*/ padding: 18px 22px; border-radius: 0; text-align: left; width: 100%; }
.product-model { font-size: 1.35rem; font-weight: 800; color: #111827; margin-bottom: 8px; transition: color .25s ease, transform .25s ease; }
.showcase-item:hover .product-model { color: #303296; }
.product-desc { font-size: .98rem; color: #4b5563; line-height: 1.65; }
.standards-section { background: var(--white); box-shadow: 0 10px 30px rgba(0,0,0,.1); border:1px solid #e5e7eb; border-radius:10px; padding:28px 30px; }
.section-head { text-align:center; margin-bottom: 2rem; }
.section-title { font-size: 2.2rem; font-weight: 800; color: var(--black); margin-bottom: .6rem; }
.section-desc { color: var(--text-gray); }
.standards-grid { display:grid; grid-template-columns: repeat(3, 1fr); gap:24px; }
.standard-card { background:#fff; border:1px solid #e5e7eb; border-radius:8px; box-shadow:0 6px 20px rgba(0,0,0,.06); padding:14px; text-decoration:none; color:inherit; transition: all .25s ease; display:flex; flex-direction:column; align-items:center; justify-content:center; }
.standard-card:hover { transform: translateY(-4px); box-shadow:0 12px 28px rgba(0,0,0,.12); border-color: var(--primary-green); }
.standard-card img { width:100%; height:220px; object-fit:contain; display:block; transition: transform .3s ease, filter .3s ease; }
.standard-card:hover img { transform: scale(1.05); filter: brightness(1.1); }
.standard-title { text-align:center; color:#374151; font-weight:700; margin-top:10px; font-size:14px; letter-spacing:.04em; }

/* Footer */
.footer { background:#1f2937; color:#fff; padding:3rem 0 2rem; /*margin-top: 4rem;*/ }
.footer-container { max-width:1400px; margin:0 auto; padding:0 10px; }
.footer-mission { font-size:1.5rem; font-weight:500; margin-bottom:3rem; color:rgba(204,204,204,1); line-height:1.6; max-width:600px; }
.footer-content { display:grid; grid-template-columns:1fr 1fr 1fr 1fr; gap:2rem; margin-bottom:2rem; }
.footer-column h3 { font-size:1.1rem; font-weight:700; margin-bottom:1rem; color:#fff; }
.footer-column ul { list-style:none; padding:0; }
.footer-column li { margin-bottom:.5rem; }
.footer-column a { color:#d1d5db; text-decoration:none; font-size:.9rem; transition:color .3s; }
.footer-column a:hover { color:#fff; }
.social-icons { display:flex; gap:1rem; margin-top:2rem; margin-bottom:2rem; }
.social-icon { width:40px; height:40px; border-radius:50%; display:flex; align-items:center; justify-content:center; text-decoration:none; transition:transform .3s; overflow:hidden; }
.social-icon:hover { transform:scale(1.1); }
.social-icon img { width:100%; height:100%; object-fit:cover; border-radius:50%; }
.footer-bottom { border-top:1px solid #374151; padding-top:1.5rem; display:flex; justify-content:space-between; align-items:center; color:#9ca3af; font-size:.9rem; }

/* Responsive */
@media (max-width: 1024px){ 
    .standards-grid { grid-template-columns: repeat(2, 1fr); }
    .showcase-grid { grid-template-columns: repeat(2, 1fr); }
    .product-image { height: 220px; }
}
@media (max-width: 768px){
    .container { padding: 0 15px; }
    .nav-links { display:none; }
    .mobile-menu-toggle { display:flex; }
    .hero { height: 320px; background-position: center top; }
    .main-content { margin-top:-80px; }
    .standards-grid { grid-template-columns: 1fr; }
    .showcase-grid { grid-template-columns: 1fr; }
    .showcase-hero { margin-bottom: 16px; }
    .showcase-hero__bg { height: 120px; }
    .showcase-title { font-size: 1.6rem; }
    .product-brand { font-size: 1.3rem; }
    .showcase-header { margin-bottom: 1rem; }
    .showcase-item { padding: 14px; }
    .product-image { height: 200px; }
    .product-info { padding: 12px 14px; }
    .product-model { font-size: 1.1rem; }
    .product-desc { font-size: .92rem; }
    .footer-content { grid-template-columns: 1fr; }
    .footer-bottom { flex-direction: column; gap: .75rem; align-items: flex-start; }
}

/* Brand VI section */
.brand-vi { background:#f3f4f6; padding: 60px 0 40px; }
.brand-title { font-size: 2rem; font-weight:800; color:#000; margin-bottom:.5rem; }
.brand-subtitle { color:#374151; margin-bottom: 1.5rem; }
.brand-grid { display:grid; grid-template-columns: repeat(2, 1fr); grid-template-rows: auto auto; gap: 20px; }
.brand-item { background:#fff; border:1px solid #e5e7eb; border-radius:8px; overflow:hidden; box-shadow: 0 6px 20px rgba(0,0,0,.06); position:relative; }
.brand-item img { width:100%; height:100%; display:block; object-fit:cover; transition: transform .3s ease, filter .3s ease; }
.brand-item:hover img { transform: scale(1.08); filter: brightness(1.15) contrast(1.1); }
.brand-caption { position:absolute; top:12px; left:12px; padding:6px 10px; background: rgba(0,0,0,.55); color:#fff; font-weight:600; font-size:14px; border-radius:4px; line-height:1; pointer-events:none; }
/* Remove spanning to keep strict 2x2 */

/*我加的*/
.brand-item .social-icon {
    width: auto;
    height: auto;
    border-radius: 0;
    display: block; /* 确保链接不影响图片布局 */
}

    .brand-item .social-icon img {
        width: 100%;
        height: 100%;
        border-radius: 0;
        object-fit: cover;
    }


@media (max-width: 1024px){
    .brand-grid { grid-template-columns: 1fr 1fr; }
    .brand-item--wide { grid-column: 1 / -1; }
}
@media (max-width: 768px){
    .brand-grid { grid-template-columns: 1fr; }
}