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

:root {
    --primary: #0097a7;
    --primary-dark: #006064;
    --primary-light: #4dd0e1;
    --primary-bg: #e0f7fa;
    --accent: #ff6f00;
    --text-primary: #1a1a2e;
    --text-secondary: #5a6a7a;
    --text-light: #8a9aaa;
    --bg-white: #fff;
    --bg-gray: #f0f3f7;
    --bg-dark: #0b1a2a;
    --bg-dark-alt: #112233;
    --border-color: #d0d8e0;
    --border-light: #e4e8ee;
    --shadow: 0 4px 24px rgba(0,0,0,0.06);
    --shadow-hover: 0 12px 40px rgba(0,0,0,0.10);
    --radius: 8px;
    --radius-lg: 16px;
    --transition: 0.30s cubic-bezier(0.4, 0, 0.2, 1);
    --font-mono: 'Cascadia Code', 'Fira Code', 'Consolas', monospace;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
    overflow-y: scroll;
    scrollbar-gutter: stable;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
    background: var(--bg-white);
}

a { color: inherit; text-decoration: none; }
ul { list-style: none; }

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

.container-wide {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 24px;
}

.section-header {
    text-align: center;
    margin-bottom: 48px;
}

.section-tag {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--primary);
    background: var(--primary-bg);
    padding: 4px 14px;
    border-radius: 20px;
    letter-spacing: 2px;
    text-transform: uppercase;
    margin-bottom: 12px;
}

.section-title {
    font-size: 2rem;
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 8px;
    line-height: 1.25;
}

.section-desc {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 640px;
    margin: 0 auto;
    line-height: 1.7;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 28px;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: 6px;
    border: 1.5px solid transparent;
    cursor: pointer;
    transition: var(--transition);
    gap: 8px;
}

.btn-primary {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

.btn-primary:hover {
    background: var(--primary-dark);
    border-color: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(0,151,167,0.3);
}

.btn-outline {
    background: transparent;
    color: var(--primary);
    border-color: var(--primary);
}

.btn-outline:hover {
    background: var(--primary);
    color: #fff;
}

.btn-white {
    background: #fff;
    color: var(--text-primary);
    border-color: #fff;
}

.btn-white:hover {
    background: rgba(255,255,255,0.85);
    transform: translateY(-1px);
}

.btn-block { width: 100%; }

.badge {
    display: inline-block;
    font-size: 0.72rem;
    font-weight: 700;
    padding: 4px 12px;
    border-radius: 4px;
    letter-spacing: 0.3px;
}

.badge-steel {
    background: #e0e4e8;
    color: #3a4a5a;
}

.badge-aluminum {
    background: #d0e8f0;
    color: #0a6a8a;
}

.badge-stainless {
    background: #e8e4e0;
    color: #6a5a4a;
}

.badge-cyan {
    background: var(--primary-bg);
    color: var(--primary);
}

.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(11, 26, 42, 0.96);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(255,255,255,0.06);
    transition: var(--transition);
}

.header.scrolled {
    background: rgba(11, 26, 42, 0.98);
    box-shadow: 0 2px 30px rgba(0,0,0,0.2);
}

.header-inner {
    display: flex;
    align-items: center;
    height: 68px;
    gap: 32px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    flex-shrink: 0;
}

.logo-img {
    width: auto;
    height: 36px;
}

.logo-text {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--primary-light);
    letter-spacing: 1px;
}

.logo-text span {
    color: var(--primary-light);
}

.nav {
    margin-right: auto;
}

.nav-list ul {
    display: flex;
    list-style: none;
    align-items: center;
    gap: 4px;
    margin: 0;
    padding: 0;
}

.nav-link {
    padding: 8px 16px;
    font-size: 0.9rem;
    font-weight: 500;
    color: rgba(255,255,255,0.7);
    border-radius: 6px;
    transition: var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: #fff;
    background: rgba(255,255,255,0.08);
}

.header .nav-phone-wrap {
    display: flex;
    align-items: center;
    gap: 16px;
}

.header-inner .nav-phone-wrap .nav-phone,
.header .nav-phone,
header .nav-phone {
    display: flex !important;
    align-items: center !important;
    gap: 8px !important;
    color: var(--primary-light) !important;
    font-size: 1.4rem !important;
    font-weight: 700 !important;
    white-space: nowrap !important;
    text-decoration: none !important;
    letter-spacing: normal !important;
    line-height: normal !important;
    width: auto !important;
    padding: 0 !important;
    margin: 0 !important;
    border: none !important;
    background: none !important;
    text-transform: none !important;
}

.header-inner .nav-phone-wrap .nav-phone .fa,
.header .nav-phone .fa,
header .nav-phone .fa {
    font-size: 1.1rem !important;
    color: var(--primary-light) !important;
    width: auto !important;
    height: auto !important;
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: #fff;
    border-radius: 2px;
    transition: var(--transition);
}

.footer {
    background: var(--bg-dark);
    color: rgba(255,255,255,0.65);
    padding: 64px 0 0;
}

.footer-top {
    display: grid;
    grid-template-columns: 1.6fr 1fr 1fr 1fr 0.8fr;
    gap: 40px;
    padding-bottom: 48px;
    border-bottom: 1px solid rgba(255,255,255,0.06);
}

.footer-brand {
    padding-right: 40px;
    font-size: 0.9rem;
    line-height: 1.7;
    color: rgba(255,255,255,0.5);
}

.footer-logo-sm {
    width: 32px;
    height: 32px;
    margin-bottom: 12px;
    filter: brightness(0) invert(1);
}

.footer h4 {
    font-size: 0.85rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 20px;
    letter-spacing: 1px;
    text-transform: uppercase;
}

.footer ul { display: flex; flex-direction: column; gap: 10px; }

.footer a {
    font-size: 0.88rem;
    color: rgba(255,255,255,0.5);
    transition: var(--transition);
}

.footer a:hover {
    color: var(--primary-light);
    padding-left: 4px;
}

.footer-links-qr ul {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.footer-qr-img img {
    width: 150px;
    height: 150px;
    border-radius: 8px;
    object-fit: cover;
}

.footer-bottom {
    padding: 20px 0;
    text-align: center;
    font-size: 0.82rem;
    color: rgba(255,255,255,0.3);
}

.footer-bottom a {
    color: rgba(255,255,255,0.4);
}

.footer-bottom a:hover {
    color: var(--primary-light);
}

.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 44px;
    height: 44px;
    border-radius: 8px;
    background: var(--primary);
    color: #fff;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
    display: flex;
    align-items: center;
    justify-content: center;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
}

@media (max-width: 992px) {
    .header-inner { gap: 16px; }
    .nav-list {
        position: fixed;
        top: 68px;
        left: 0;
        width: 100%;
        background: rgba(11,26,42,0.98);
        padding: 16px 24px;
        max-height: 0;
        overflow: hidden;
        transition: max-height 0.35s ease;
        border-bottom: 1px solid rgba(255,255,255,0.06);
    }
    .nav-list.open { max-height: 500px; }
    .nav-list ul { flex-direction: column; align-items: stretch; gap: 2px; }
    .nav-toggle { display: flex; }
    .header .nav-phone-wrap { gap: 8px; }
    .header .nav-phone { font-size: 1rem !important; }
    .footer-top { grid-template-columns: 1fr 1fr; gap: 30px; }
}

@media (max-width: 768px) {
    .footer-top { grid-template-columns: 1fr; gap: 24px; }
    .container { padding: 0 16px; }
}