/*
  翼联工贸 - Alberti 中国官网 (Static Chinese Site)
  Design system derived from Alberti Umberto Elementor kit
  Primary: #B0223E | Dark header: #0f172a | Light: #f8f9fa | White: #fff
*/
:root {
  --primary: #B0223E;
  --primary-dark: #8a1a30;
  --primary-light: #d4405a;
  --dark: #0f172a;
  --dark-2: #1e293b;
  --text: #1a1a2e;
  --text-light: #4a5568;
  --text-muted: #718096;
  --bg: #f8f9fa;
  --white: #ffffff;
  --border: #e2e8f0;
  --blue: #6AC5EE;
  --container: 1200px;
  --radius: 8px;
  --radius-lg: 16px;
  --shadow: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-lg: 0 12px 48px rgba(0,0,0,0.12);
  --transition: all 0.3s ease;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color: var(--text);
  line-height: 1.7;
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--primary); text-decoration: none; transition: var(--transition); }
a:hover { color: var(--primary-dark); }
img { max-width: 100%; height: auto; display: block; }
ul { list-style: none; }

.container { max-width: var(--container); margin: 0 auto; padding: 0 24px; }

/* ===== HEADER ===== */
.site-header {
  position: sticky; top: 0; z-index: 1000;
  background: var(--dark);
  box-shadow: 0 2px 20px rgba(0,0,0,0.3);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 72px;
}
.logo {
  display: flex; align-items: center; gap: 12px; color: var(--white); font-weight: 700;
  font-size: 1.2rem; text-decoration: none;
}
.logo img { height: 40px; width: auto; }
.logo-text { line-height: 1.2; }
.logo-text small { display: block; font-size: 0.7rem; color: #94a3b8; font-weight: 400; }

.main-nav { display: flex; align-items: center; gap: 4px; }
.main-nav a {
  color: #cbd5e1; padding: 8px 16px; border-radius: 6px; font-size: 0.95rem;
  font-weight: 500; text-decoration: none; transition: var(--transition);
}
.main-nav a:hover, .main-nav a.active { color: var(--white); background: rgba(255,255,255,0.08); }
.main-nav a.cta-btn {
  background: var(--primary); color: var(--white); padding: 8px 20px; margin-left: 8px;
  border-radius: 6px; font-weight: 600;
}
.main-nav a.cta-btn:hover { background: var(--primary-light); color: var(--white); }

.nav-toggle { display: none; flex-direction: column; gap: 5px; cursor: pointer; padding: 8px; background: none; border: none; }
.nav-toggle span { display: block; width: 24px; height: 2px; background: var(--white); border-radius: 2px; transition: var(--transition); }
.nav-toggle.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.nav-toggle.active span:nth-child(2) { opacity: 0; }
.nav-toggle.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ===== HERO ===== */
.hero {
  position: relative; min-height: 600px;
  display: flex; align-items: center;
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; inset: 0;
  background: url('../images/hero-bg.jpg') center/cover no-repeat;
  opacity: 0.25; mix-blend-mode: luminosity;
}
.hero-content { position: relative; z-index: 2; padding: 80px 0; }
.hero-badge {
  display: inline-block; background: var(--primary); color: var(--white);
  padding: 6px 16px; border-radius: 50px; font-size: 0.85rem; font-weight: 600;
  margin-bottom: 20px; letter-spacing: 1px;
}
.hero h1 {
  font-size: clamp(2rem, 5vw, 3.5rem); font-weight: 800; color: var(--white);
  line-height: 1.2; margin-bottom: 16px; max-width: 700px;
}
.hero h1 span { color: var(--primary-light); }
.hero p { font-size: 1.15rem; color: #cbd5e1; max-width: 600px; margin-bottom: 32px; line-height: 1.8; }
.hero-btns { display: flex; gap: 16px; flex-wrap: wrap; }

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 28px; border-radius: 8px; font-size: 1rem; font-weight: 600;
  border: none; cursor: pointer; transition: var(--transition); text-decoration: none;
}
.btn-primary { background: var(--primary); color: var(--white); }
.btn-primary:hover { background: var(--primary-dark); color: var(--white); transform: translateY(-2px); box-shadow: 0 8px 24px rgba(176,34,62,0.4); }
.btn-outline { background: transparent; color: var(--white); border: 2px solid rgba(255,255,255,0.4); }
.btn-outline:hover { border-color: var(--white); background: rgba(255,255,255,0.05); color: var(--white); }

.hero-stats {
  position: relative; z-index: 2; display: flex; gap: 40px;
  padding: 32px 0; border-top: 1px solid rgba(255,255,255,0.1); margin-top: 48px;
}
.stat-item { text-align: center; }
.stat-number { font-size: 2.5rem; font-weight: 800; color: var(--white); line-height: 1; }
.stat-number span { color: var(--primary-light); }
.stat-label { font-size: 0.85rem; color: #94a3b8; margin-top: 4px; }

/* ===== SECTIONS ===== */
.section { padding: 80px 0; }
.section-dark { background: var(--dark); color: var(--white); }
.section-gray { background: var(--bg); }
.section-header { text-align: center; margin-bottom: 60px; }
.section-header h2 {
  font-size: clamp(1.8rem, 3vw, 2.5rem); font-weight: 800;
  margin-bottom: 16px; color: var(--text);
}
.section-dark .section-header h2 { color: var(--white); }
.section-header .subtitle { color: var(--text-muted); font-size: 1.1rem; max-width: 600px; margin: 0 auto; }
.section-dark .section-header .subtitle { color: #94a3b8; }

.section-divider {
  height: 3px; width: 60px; background: var(--primary); margin: 16px auto 0;
  border-radius: 2px;
}

/* ===== APPLICATION GRID ===== */
.app-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.app-card {
  position: relative; border-radius: var(--radius-lg); overflow: hidden;
  aspect-ratio: 4/3; cursor: pointer; display: flex; align-items: flex-end;
}
.app-card::before {
  content: ''; position: absolute; inset: 0;
  background: linear-gradient(to top, rgba(0,0,0,0.8) 0%, rgba(0,0,0,0.2) 100%);
  z-index: 1;
}
.app-card img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s ease; }
.app-card:hover img { transform: scale(1.05); }
.app-card-content { position: relative; z-index: 2; padding: 24px; width: 100%; }
.app-card-content h3 { color: var(--white); font-size: 1.3rem; font-weight: 700; margin-bottom: 4px; }
.app-card-content p { color: #94a3b8; font-size: 0.85rem; display: none; }
.app-card:hover .app-card-content p { display: block; }

/* ===== PRODUCT GRID ===== */
.product-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 24px; }
.product-card {
  background: var(--white); border-radius: var(--radius-lg); overflow: hidden;
  box-shadow: var(--shadow); transition: var(--transition); border: 1px solid var(--border);
}
.product-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); }
.product-card-img {
  aspect-ratio: 4/3; overflow: hidden; background: #f1f5f9;
  display: flex; align-items: center; justify-content: center;
}
.product-card-img img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s ease; }
.product-card:hover .product-card-img img { transform: scale(1.05); }
.product-card-body { padding: 20px; }
.product-card-body h3 { font-size: 1rem; font-weight: 700; margin-bottom: 6px; color: var(--text); line-height: 1.4; }
.product-card-body .product-cat { font-size: 0.8rem; color: var(--primary); font-weight: 600; margin-bottom: 8px; }
.product-card-body .product-desc { font-size: 0.85rem; color: var(--text-muted); line-height: 1.6; margin-bottom: 12px; }
.product-card-body .product-link { font-size: 0.9rem; font-weight: 600; color: var(--primary); display: inline-flex; align-items: center; gap: 4px; }

/* ===== CATEGORY CARDS ===== */
.cat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 24px; }
.cat-card {
  background: var(--white); border-radius: var(--radius-lg); overflow: hidden;
  box-shadow: var(--shadow); border: 1px solid var(--border); transition: var(--transition);
  display: flex; flex-direction: column;
}
.cat-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--primary); }
.cat-card-img { aspect-ratio: 16/9; overflow: hidden; background: #f1f5f9; }
.cat-card-img img { width: 100%; height: 100%; object-fit: cover; }
.cat-card-body { padding: 24px; flex: 1; display: flex; flex-direction: column; }
.cat-card-body h3 { font-size: 1.2rem; font-weight: 700; margin-bottom: 8px; color: var(--text); }
.cat-card-body p { font-size: 0.9rem; color: var(--text-muted); line-height: 1.7; flex: 1; margin-bottom: 16px; }
.cat-card-body .cat-link { font-weight: 600; color: var(--primary); display: inline-flex; align-items: center; gap: 4px; }

/* ===== PRODUCT DETAIL ===== */
.product-hero { background: linear-gradient(135deg, var(--dark) 0%, var(--dark-2) 100%); padding: 60px 0; }
.product-hero-inner { display: flex; gap: 48px; align-items: center; }
.product-hero-img { flex: 1; border-radius: var(--radius-lg); overflow: hidden; }
.product-hero-img img { width: 100%; border-radius: var(--radius-lg); }
.product-hero-info { flex: 1; color: var(--white); }
.product-hero-info h1 { font-size: 2.2rem; font-weight: 800; margin-bottom: 8px; }
.product-hero-info .product-series { color: var(--primary-light); font-weight: 600; margin-bottom: 16px; }
.product-hero-info .product-desc { color: #94a3b8; line-height: 1.8; margin-bottom: 24px; }
.product-hero-info .product-sku { font-size: 0.9rem; color: #64748b; margin-bottom: 20px; }

.product-specs { padding: 60px 0; }
.specs-table { width: 100%; border-collapse: collapse; }
.specs-table tr:nth-child(even) { background: var(--bg); }
.specs-table th { background: var(--dark); color: var(--white); padding: 12px 20px; text-align: left; font-weight: 600; }
.specs-table td { padding: 12px 20px; border-bottom: 1px solid var(--border); }
.specs-table td:first-child { font-weight: 600; color: var(--text); width: 200px; }

/* ===== PROCESS STEPS ===== */
.process-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 24px; }
.process-card {
  background: var(--white); border-radius: var(--radius-lg); padding: 32px 20px;
  text-align: center; box-shadow: var(--shadow); border: 1px solid var(--border);
  position: relative; transition: var(--transition);
}
.process-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: var(--primary); }
.process-number {
  width: 48px; height: 48px; border-radius: 50%; background: var(--primary);
  color: var(--white); display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem; font-weight: 800; margin: 0 auto 16px;
}
.process-card h4 { font-size: 1rem; font-weight: 700; margin-bottom: 8px; color: var(--text); }
.process-card p { font-size: 0.85rem; color: var(--text-muted); line-height: 1.6; }

/* ===== FEATURES ===== */
.features-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.feature-card {
  background: var(--white); border-radius: var(--radius-lg); padding: 32px;
  text-align: center; box-shadow: var(--shadow); border: 1px solid var(--border);
  transition: var(--transition);
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.feature-icon {
  width: 64px; height: 64px; border-radius: 50%; background: rgba(176,34,62,0.1);
  color: var(--primary); display: flex; align-items: center; justify-content: center;
  font-size: 1.8rem; margin: 0 auto 16px;
}
.feature-card h4 { font-size: 1.1rem; font-weight: 700; margin-bottom: 8px; }
.feature-card p { font-size: 0.9rem; color: var(--text-muted); line-height: 1.6; }

/* ===== CTA BANNER ===== */
.cta-banner {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  padding: 64px 0; text-align: center; color: var(--white);
}
.cta-banner h2 { font-size: clamp(1.5rem, 3vw, 2.2rem); font-weight: 800; margin-bottom: 12px; }
.cta-banner p { color: rgba(255,255,255,0.85); margin-bottom: 28px; font-size: 1.1rem; }
.cta-banner .btn { background: var(--white); color: var(--primary); }
.cta-banner .btn:hover { background: #fef2f4; color: var(--primary-dark); transform: translateY(-2px); }

/* ===== CONTACT FORM ===== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; }
.contact-info { }
.contact-info h3 { font-size: 1.4rem; font-weight: 700; margin-bottom: 24px; }
.contact-item { display: flex; gap: 16px; margin-bottom: 24px; }
.contact-icon {
  width: 48px; height: 48px; border-radius: 50%; background: rgba(176,34,62,0.1);
  color: var(--primary); display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem; flex-shrink: 0;
}
.contact-item-text h4 { font-size: 0.95rem; font-weight: 700; margin-bottom: 4px; }
.contact-item-text p { font-size: 0.9rem; color: var(--text-muted); }
.contact-item-text a { color: var(--primary); }

.contact-form { background: var(--white); padding: 40px; border-radius: var(--radius-lg); box-shadow: var(--shadow); border: 1px solid var(--border); }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; font-size: 0.9rem; font-weight: 600; margin-bottom: 6px; }
.form-group input, .form-group textarea, .form-group select {
  width: 100%; padding: 12px 16px; border: 1px solid var(--border); border-radius: 8px;
  font-size: 0.95rem; font-family: inherit; transition: var(--transition); background: var(--bg);
}
.form-group input:focus, .form-group textarea:focus, .form-group select:focus {
  outline: none; border-color: var(--primary); background: var(--white); box-shadow: 0 0 0 3px rgba(176,34,62,0.1);
}
.form-group textarea { min-height: 120px; resize: vertical; }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }

/* ===== FOOTER ===== */
.site-footer { background: var(--dark); color: #94a3b8; padding: 60px 0 0; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 48px; padding-bottom: 40px; border-bottom: 1px solid rgba(255,255,255,0.08); }
.footer-brand h3 { color: var(--white); font-size: 1.2rem; font-weight: 700; margin-bottom: 12px; }
.footer-brand p { font-size: 0.9rem; line-height: 1.7; margin-bottom: 20px; }
.social-links { display: flex; gap: 12px; }
.social-link {
  width: 36px; height: 36px; border-radius: 50%; background: rgba(255,255,255,0.08);
  color: #94a3b8; display: flex; align-items: center; justify-content: center;
  font-size: 0.9rem; transition: var(--transition);
}
.social-link:hover { background: var(--primary); color: var(--white); }

.footer-nav h4 { color: var(--white); font-size: 0.95rem; font-weight: 700; margin-bottom: 16px; }
.footer-nav ul li { margin-bottom: 10px; }
.footer-nav a { color: #94a3b8; font-size: 0.9rem; transition: var(--transition); }
.footer-nav a:hover { color: var(--white); }

.footer-bottom { padding: 24px 0; text-align: center; font-size: 0.85rem; color: #64748b; }
.footer-bottom a { color: #64748b; }
.footer-bottom a:hover { color: var(--primary-light); }

/* ===== BREADCRUMB ===== */
.breadcrumb { padding: 16px 0; background: var(--bg); border-bottom: 1px solid var(--border); }
.breadcrumb-inner { display: flex; align-items: center; gap: 8px; font-size: 0.85rem; color: var(--text-muted); }
.breadcrumb a { color: var(--text-muted); }
.breadcrumb a:hover { color: var(--primary); }
.breadcrumb .sep { color: var(--border); }

/* ===== MOBILE MENU ===== */
@media (max-width: 1024px) {
  .nav-toggle { display: flex; }
  .main-nav {
    display: none; position: absolute; top: 72px; left: 0; right: 0;
    background: var(--dark); flex-direction: column; padding: 16px 24px;
    box-shadow: 0 8px 24px rgba(0,0,0,0.3); gap: 0;
  }
  .main-nav.active { display: flex; }
  .main-nav a { padding: 12px 16px; width: 100%; }
  .main-nav a.cta-btn { margin-left: 0; margin-top: 8px; text-align: center; }

  .app-grid { grid-template-columns: repeat(2, 1fr); }
  .process-grid { grid-template-columns: repeat(2, 1fr); }
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .product-hero-inner { flex-direction: column; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .hero-stats { flex-wrap: wrap; gap: 20px; }
}

@media (max-width: 640px) {
  .app-grid { grid-template-columns: 1fr; }
  .process-grid { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: 1fr; }
  .product-grid { grid-template-columns: 1fr; }
  .cat-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 32px; }
  .form-row { grid-template-columns: 1fr; }
  .hero-stats { flex-direction: column; align-items: flex-start; }
  .section { padding: 48px 0; }
}

/* ===== UTILITY ===== */
.text-center { text-align: center; }
.text-primary { color: var(--primary); }
.mb-0 { margin-bottom: 0; }
.mt-0 { margin-top: 0; }
.lead { font-size: 1.1rem; color: var(--text-muted); line-height: 1.8; }

.back-to-top {
  position: fixed; bottom: 24px; right: 24px; z-index: 999;
  width: 44px; height: 44px; border-radius: 50%;
  background: var(--primary); color: var(--white);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.2rem; cursor: pointer; border: none;
  box-shadow: var(--shadow-lg); opacity: 0; pointer-events: none;
  transition: var(--transition);
}
.back-to-top.visible { opacity: 1; pointer-events: auto; }
.back-to-top:hover { background: var(--primary-dark); transform: translateY(-3px); }

.fade-in { opacity: 0; transform: translateY(20px); transition: opacity 0.6s ease, transform 0.6s ease; }
.fade-in.visible { opacity: 1; transform: none; }

/* ===== PAGE HERO ===== */
.page-hero { background: linear-gradient(135deg, var(--dark) 0%, var(--dark-2) 100%); padding: 80px 0 60px; text-align: center; color: var(--white); }
.page-hero h1 { font-size: clamp(1.8rem, 3.5vw, 2.8rem); font-weight: 800; margin-bottom: 12px; }
.page-hero p { color: #94a3b8; font-size: 1.1rem; max-width: 600px; margin: 0 auto; }

/* ===== BANNER ===== */
.banner-section { position: relative; padding: 64px 0; overflow: hidden; }
.banner-section::before {
  content: ''; position: absolute; inset: 0;
  background-size: cover; background-position: center; opacity: 0.08;
}

/* ===== COMPANY HIGHLIGHTS ===== */
.highlights-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.highlight-card {
  background: var(--white); border-radius: var(--radius-lg); padding: 40px 28px;
  text-align: center; box-shadow: var(--shadow); border: 1px solid var(--border);
  transition: var(--transition);
}
.highlight-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }
.highlight-icon {
  width: 72px; height: 72px; border-radius: 50%;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  color: var(--white); display: flex; align-items: center; justify-content: center;
  font-size: 2rem; margin: 0 auto 20px;
}
.highlight-card h4 { font-size: 1.1rem; font-weight: 700; margin-bottom: 8px; }
.highlight-card p { font-size: 0.9rem; color: var(--text-muted); line-height: 1.7; }

/* ===== FAQ ===== */
.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item { border-bottom: 1px solid var(--border); }
.faq-question {
  display: flex; justify-content: space-between; align-items: center;
  padding: 20px 0; cursor: pointer; font-weight: 600; font-size: 1.05rem;
}
.faq-question::after { content: '+'; font-size: 1.5rem; color: var(--primary); transition: var(--transition); }
.faq-item.open .faq-question::after { content: '−'; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.3s ease, padding 0.3s ease; }
.faq-item.open .faq-answer { max-height: 500px; padding-bottom: 20px; }
.faq-answer p { color: var(--text-muted); line-height: 1.8; }

/* ===== TWO-COLUMN ===== */
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.two-col-img { border-radius: var(--radius-lg); overflow: hidden; }
.two-col-img img { width: 100%; border-radius: var(--radius-lg); }
.two-col-text h2 { font-size: clamp(1.5rem, 3vw, 2.2rem); font-weight: 800; margin-bottom: 16px; }
.two-col-text .subtitle { color: var(--text-muted); margin-bottom: 24px; line-height: 1.8; }
.two-col-text .feature-list { margin: 24px 0; }
.two-col-text .feature-list li { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; font-size: 0.95rem; }
.two-col-text .feature-list li::before {
  content: '✓'; width: 24px; height: 24px; border-radius: 50%;
  background: rgba(176,34,62,0.1); color: var(--primary);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.8rem; font-weight: 700; flex-shrink: 0;
}

@media (max-width: 768px) {
  .two-col { grid-template-columns: 1fr; gap: 32px; }
}

/* ===== SPEC TABLE (PRODUCT PAGE) ===== */
.spec-section { padding: 60px 0; }
.spec-section h3 { font-size: 1.5rem; font-weight: 700; margin-bottom: 24px; }
.param-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.param-item { background: var(--bg); border-radius: var(--radius); padding: 16px 20px; }
.param-item strong { display: block; font-size: 0.8rem; color: var(--text-muted); margin-bottom: 4px; text-transform: uppercase; letter-spacing: 0.5px; }
.param-item span { font-size: 1rem; font-weight: 600; color: var(--text); }

@media (max-width: 768px) { .param-grid { grid-template-columns: 1fr; } }

/* ===== SCROLLBAR ===== */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: #cbd5e1; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #94a3b8; }