/* ========== CSS Variables — 清爽暖灰·精密制造风 ========== */
:root {
    --bg:              #faf9f7;
    --surface:         #ffffff;
    --surface-alt:     #f4f2ee;
    --text-main:       #1f1f1f;
    --text-secondary:  #6b6b6b;
    --border:          #e8e5df;
    --primary:         #d94f1a;    /* 低饱和暖橙 */
    --primary-light:   #f7c9b6;    /* 浅橙底 */
    --primary-hover:   #c04517;
    --accent:          #2a7d8c;    /* 青蓝灰 */
    --shadow:          rgba(0,0,0,.06);
    --shadow-md:       rgba(0,0,0,.10);
    --shadow-lg:       rgba(0,0,0,.14);
    --radius-sm:       8px;
    --radius-md:       12px;
    --radius-lg:       16px;
    --radius-full:     9999px;
    --transition:      .3s cubic-bezier(.4,0,.2,1);
}

/* ========== Reset & Base ========== */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html {
    scroll-behavior: smooth;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI',
                 'PingFang SC', 'Microsoft YaHei', sans-serif;
    color: var(--text-main);
    background: var(--bg);
    line-height: 1.75;
    overflow-x: hidden;
}

a { text-decoration: none; color: inherit; transition: color var(--transition); }
img { max-width: 100%; display: block; }
ul { list-style: none; }
button, input, textarea { font-family: inherit; outline: none; }

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

/* ========== Utility ========== */
.section-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 1.2px;
    text-transform: uppercase;
    color: var(--primary);
    background: var(--primary-light);
    padding: 6px 16px;
    border-radius: var(--radius-full);
    margin-bottom: 16px;
}
.section-badge::before {
    content: '';
    width: 6px; height: 6px;
    background: var(--primary);
    border-radius: 50%;
}

.section-title {
    font-size: clamp(26px, 3.5vw, 36px);
    font-weight: 700;
    line-height: 1.25;
    letter-spacing: -0.3px;
    color: var(--text-main);
    margin-bottom: 16px;
}

.section-desc {
    font-size: 16px;
    line-height: 1.8;
    color: var(--text-secondary);
    max-width: 560px;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 13px 30px;
    font-size: 15px;
    font-weight: 600;
    border-radius: var(--radius-sm);
    border: 2px solid transparent;
    cursor: pointer;
    transition: all var(--transition);
    letter-spacing: .3px;
}
.btn-primary {
    background: var(--primary);
    color: #fff;
}
.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(217,79,26,.25);
}
.btn-outline {
    background: transparent;
    color: var(--primary);
    border-color: var(--primary);
}
.btn-outline:hover {
    background: var(--primary);
    color: #fff;
    transform: translateY(-2px);
}
.btn-white {
    background: #fff;
    color: var(--primary);
}
.btn-white:hover {
    background: #f5f5f5;
    transform: translateY(-2px);
}

.text-gradient {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* ========== Top Bar ========== */
.top-bar {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 10px 0;
    font-size: 13px;
    color: var(--text-secondary);
}
.top-bar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.top-bar a { color: var(--text-secondary); }
.top-bar a:hover { color: var(--primary); }
.top-bar i { margin-right: 6px; color: var(--primary); }
.top-social { display: flex; gap: 14px; }
.top-social a {
    width: 30px; height: 30px;
    display: flex; align-items: center; justify-content: center;
    border-radius: 50%;
    background: var(--surface-alt);
    font-size: 13px;
}
.top-social a:hover {
    background: var(--primary);
    color: #fff;
}

/* ========== Navbar ========== */
.navbar {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: box-shadow var(--transition);
}
.navbar.scrolled {
    box-shadow: 0 2px 16px var(--shadow-md);
}
.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}
.logo {
    font-size: 22px;
    font-weight: 800;
    letter-spacing: 1.5px;
    color: var(--text-main);
}
.logo span { color: var(--primary); }

.nav-links {
    display: flex;
    align-items: center;
    gap: 6px;
}
.nav-links a {
    padding: 8px 16px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: var(--radius-sm);
    transition: all var(--transition);
    position: relative;
}
.nav-links a:hover,
.nav-links a.active {
    color: var(--primary);
    background: var(--primary-light);
}
.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: 2px; left: 50%; transform: translateX(-50%);
    width: 18px; height: 2px;
    background: var(--primary);
    border-radius: 1px;
}

.nav-right {
    display: flex;
    align-items: center;
    gap: 12px;
}
.lang-switch {
    font-size: 13px;
    font-weight: 500;
    color: var(--text-secondary);
    padding: 6px 12px;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    cursor: pointer;
    background: var(--surface);
}
.lang-switch:hover { border-color: var(--primary); color: var(--primary); }

/* Hamburger */
.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    padding: 6px;
    z-index: 1001;
}
.hamburger span {
    width: 24px; height: 2px;
    background: var(--text-main);
    border-radius: 2px;
    transition: all var(--transition);
}
.hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* Mobile Nav */
.mobile-nav {
    display: none;
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: var(--surface);
    z-index: 999;
    padding: 100px 32px 40px;
    flex-direction: column;
    gap: 4px;
    overflow-y: auto;
}
.mobile-nav.active { display: flex; }
.mobile-nav a {
    padding: 14px 16px;
    font-size: 16px;
    font-weight: 500;
    color: var(--text-main);
    border-radius: var(--radius-sm);
}
.mobile-nav a:hover,
.mobile-nav a.active { color: var(--primary); background: var(--primary-light); }
.mobile-nav .btn { margin-top: 16px; text-align: center; justify-content: center; }



/* ========== CTA Section ========== */
.cta-section {
    padding: 80px 0;
    background: var(--surface);
}
.cta-box {
    background: linear-gradient(135deg, var(--primary) 0%, #c04517 100%);
    border-radius: var(--radius-lg);
    padding: 64px 48px;
    text-align: center;
    color: #fff;
}
.cta-box h2 {
    font-size: clamp(24px, 3vw, 36px);
    font-weight: 700;
    margin-bottom: 16px;
}
.cta-box p {
    font-size: 16px;
    opacity: .9;
    margin-bottom: 32px;
    max-width: 520px;
    margin-left: auto; margin-right: auto;
}
.cta-box .btn-white { font-size: 16px; padding: 14px 36px; }

/* ========== Footer ========== */
.footer {
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: 72px 0 48px;
}
.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr 1fr 1.2fr;
    gap: 40px;
    margin-bottom: 48px;
}
.footer-brand .logo { margin-bottom: 16px; }
.footer-brand p {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 20px;
}
.footer-social { display: flex; gap: 10px; }
.footer-social a {
    width: 38px; height: 38px;
    display: flex; align-items: center; justify-content: center;
    border-radius: 50%;
    background: var(--surface-alt);
    color: var(--text-secondary);
    font-size: 15px;
}
.footer-social a:hover { background: var(--primary); color: #fff; }

.footer-col h4 {
    font-size: 14px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-main);
    margin-bottom: 18px;
}
.footer-col ul li { margin-bottom: 10px; }
.footer-col ul li a {
    font-size: 14px;
    color: var(--text-secondary);
}
.footer-col ul li a:hover { color: var(--primary); }

.footer-contact p {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}
.footer-contact i { color: var(--primary); width: 16px; }

.footer-bottom {
    border-top: 1px solid var(--border);
    padding-top: 24px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 13px;
    color: var(--text-secondary);
}

/* ========== Back to Top ========== */
.back-to-top {
    position: fixed;
    bottom: 32px; right: 32px;
    width: 44px; height: 44px;
    background: var(--primary);
    color: #fff;
    border: none;
    border-radius: 50%;
    font-size: 18px;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: all var(--transition);
    z-index: 999;
    display: flex; align-items: center; justify-content: center;
    box-shadow: 0 4px 16px rgba(217,79,26,.25);
}
.back-to-top.visible {
    opacity: 1; visibility: visible; transform: translateY(0);
}
.back-to-top:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
}

/* ========== Scroll Animation ========== */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity .7s ease, transform .7s ease;
}
.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========== Responsive ========== */
@media (max-width: 1200px) {
    .footer-grid { grid-template-columns: 1.5fr 1fr 1fr 1fr 1.5fr; }
}

@media (max-width: 1024px) {
    .hero .container { grid-template-columns: 1fr; gap: 40px; }
    .hero-content { max-width: 100%; }
    .hero-image img { height: 100%; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
    .products-grid { grid-template-columns: repeat(2, 1fr); }
    .why-grid { grid-template-columns: 1fr; gap: 48px; }
    .why-right { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: 1fr 1fr 1fr 1.5fr; gap: 32px; }
}

@media (max-width: 768px) {
    .top-bar { display: none; }
    .nav-links, .nav-right .btn { display: none; }
    .hamburger { display: flex; }
    .hero { padding: 64px 0 56px; }
    .hero h1 { font-size: clamp(28px, 6vw, 40px); }
    .hero-buttons { flex-direction: column; }
    .hero-buttons .btn { width: 100%; justify-content: center; }
    .hero-image img { height: 260px; }
    .stats-grid { grid-template-columns: 1fr 1fr; gap: 16px; }
    .stat-number { font-size: 28px; }
    .products-grid { grid-template-columns: 1fr; }
    .product-img { height: 200px; }
    .why-features { grid-template-columns: 1fr; }
    .why-right { grid-template-columns: 1fr; }
    .grid4 { grid-template-columns: 1fr; }
    .grid4-item { padding: 32px 28px; }
    .cert-logos { gap: 28px; }
    .cta-box { padding: 48px 28px; }
    .footer-grid { grid-template-columns: 1fr 1fr; gap: 28px; }
    .footer-bottom { flex-direction: column; gap: 12px; text-align: center; }
}

@media (max-width: 480px) {
    .container { padding: 0 16px; }
    .hero { padding: 48px 0 40px; }
    .hero h1 { font-size: clamp(24px, 7vw, 32px); }
    .stats-grid { grid-template-columns: 1fr 1fr; gap: 12px; }
    .stat-item { padding: 16px 8px; }
    .stat-number { font-size: 24px; }
    .stat-label { font-size: 12px; }
    .section-title { font-size: clamp(22px, 5vw, 28px); }
    .why-grid { gap: 32px; }
    .grid4-item { padding: 24px 20px; }
    .cta-box { padding: 36px 20px; }
    .footer-grid { grid-template-columns: 1fr; }
}