:root {
  --primary: #15395B;
  --primary-dark: #0f2a42;
  --secondary: #33383D;
  --silver: #C2CAD2;
  --silver-dark: #9AA6B0;
  --bg: #F4F7FA;
  --white: #FFFFFF;
  --text: #2A3036;
  --text-light: #5D646C;
  --border: #DDE3E8;
  --radius: 6px;
  --shadow: 0 4px 20px rgba(21,57,91,0.08);
  --shadow-hover: 0 8px 30px rgba(21,57,91,0.14);
  --transition: 0.25s ease;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0; padding: 0;
  font-family: "Microsoft YaHei", "SimHei", "Heiti SC", Arial, sans-serif;
  color: var(--text); background: var(--bg);
  line-height: 1.7;
}
img, svg { max-width: 100%; height: auto; display: block; }
a { color: var(--primary); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--primary-dark); }

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* Header */
.site-header {
  background: var(--white); border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 1000; box-shadow: 0 2px 10px rgba(0,0,0,0.04);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between; height: 80px;
}
.logo { display: flex; align-items: center; }
.logo img { height: 50px; width: auto; }

.nav-links {
  display: flex; align-items: center; gap: 10px; list-style: none; margin: 0; padding: 0;
}
.nav-links a {
  display: block; padding: 8px 12px; color: var(--text); font-size: 15px; font-weight: 500;
  border-radius: var(--radius);
}
.nav-links a:hover, .nav-links a.active {
  color: var(--primary); background: rgba(21,57,91,0.06);
}

.mobile-menu-btn {
  display: none; background: none; border: 1px solid var(--border); border-radius: var(--radius);
  padding: 8px 10px; cursor: pointer;
}
.mobile-menu-btn span {
  display: block; width: 22px; height: 2px; background: var(--secondary); margin: 5px 0; transition: var(--transition);
}

/* Hero */
.hero {
  position: relative; height: 520px; overflow: hidden;
  display: flex; align-items: center; justify-content: center; text-align: center;
}
.hero-bg {
  position: absolute; inset: 0; z-index: 0;
  background: linear-gradient(135deg, rgba(21,57,91,0.88), rgba(51,56,61,0.82)), url('../images/banner.svg');
  background-size: cover; background-position: center;
}
.hero-content { position: relative; z-index: 1; color: var(--white); max-width: 900px; padding: 0 20px; }
.hero h1 { font-size: 36px; margin: 0 0 18px; letter-spacing: 1px; line-height: 1.3; }
.hero p { font-size: 18px; margin: 0 0 30px; opacity: 0.92; }

.btn {
  display: inline-block; padding: 12px 28px; border-radius: var(--radius); font-size: 15px;
  font-weight: 600; transition: var(--transition); border: 2px solid transparent; cursor: pointer;
}
.btn-primary { background: var(--primary); color: var(--white); }
.btn-primary:hover { background: var(--primary-dark); color: var(--white); }
.btn-outline { border-color: var(--white); color: var(--white); background: rgba(255,255,255,0.08); }
.btn-outline:hover { background: var(--white); color: var(--primary); }

/* Sections */
.section { padding: 70px 0; }
.section-title {
  font-size: 28px; color: var(--primary); margin: 0 0 12px; text-align: center; font-weight: 700;
}
.section-subtitle {
  text-align: center; color: var(--text-light); margin: 0 0 40px; font-size: 16px;
}
.section.bg-white { background: var(--white); }

/* Grid layouts */
.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-5 { grid-template-columns: repeat(5, 1fr); }

/* Cards */
.card {
  background: var(--white); border: 1px solid var(--border); border-radius: var(--radius);
  overflow: hidden; box-shadow: var(--shadow); transition: var(--transition);
}
.card:hover { transform: translateY(-4px); box-shadow: var(--shadow-hover); }
.card-img { height: 220px; background: var(--bg); display: flex; align-items: center; justify-content: center; padding: 20px; }
.card-img img { max-height: 100%; max-width: 100%; object-fit: contain; }
.card-body { padding: 22px; }
.card-body h3 { margin: 0 0 10px; font-size: 18px; color: var(--primary); }
.card-body p { margin: 0; color: var(--text-light); font-size: 14px; }

/* Intro */
.intro-text { max-width: 900px; margin: 0 auto; text-align: center; font-size: 17px; color: var(--text); }

/* Advantages */
.advantage {
  text-align: center; padding: 28px 20px; background: var(--white); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); transition: var(--transition);
}
.advantage:hover { border-color: var(--primary); transform: translateY(-3px); }
.advantage .icon {
  width: 56px; height: 56px; margin: 0 auto 14px; border: 2px solid var(--silver); border-radius: 50%;
  display: flex; align-items: center; justify-content: center; font-size: 24px; color: var(--primary);
}
.advantage h4 { margin: 0 0 8px; font-size: 17px; color: var(--primary); }
.advantage p { margin: 0; font-size: 14px; color: var(--text-light); }

/* Knowledge preview / article */
.knowledge-item {
  display: flex; gap: 18px; align-items: flex-start; padding: 22px; background: var(--white);
  border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow);
}
.knowledge-item .num {
  flex: 0 0 44px; height: 44px; border-radius: 50%; background: var(--primary); color: var(--white);
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 18px;
}
.knowledge-item h4 { margin: 0 0 8px; color: var(--primary); }
.knowledge-item p { margin: 0; font-size: 14px; color: var(--text-light); }

/* Case / feedback */
.case-card { display: flex; flex-direction: column; background: var(--white); border-radius: var(--radius); overflow: hidden; border: 1px solid var(--border); box-shadow: var(--shadow); }
.case-card .case-img { height: 220px; background: var(--bg); }
.case-card .case-img img { width: 100%; height: 100%; object-fit: cover; }
.case-card .case-body { padding: 22px; flex: 1; }
.case-card h4 { margin: 0 0 10px; color: var(--primary); }
.case-card p { margin: 0; font-size: 14px; color: var(--text-light); }

.feedback-card { background: var(--white); border-left: 4px solid var(--primary); padding: 22px; border-radius: var(--radius); box-shadow: var(--shadow); }
.feedback-card img { height: 180px; width: 100%; object-fit: cover; border-radius: var(--radius); margin-bottom: 14px; }
.feedback-card blockquote { margin: 0 0 10px; font-style: normal; font-size: 15px; color: var(--text); }
.feedback-card cite { font-size: 14px; color: var(--text-light); }

/* Contact info */
.contact-info { background: var(--white); padding: 30px; border-radius: var(--radius); box-shadow: var(--shadow); }
.contact-info h3 { margin: 0 0 18px; color: var(--primary); font-size: 20px; }
.contact-info .line { display: flex; margin-bottom: 14px; font-size: 15px; }
.contact-info .label { width: 70px; color: var(--text-light); flex: 0 0 70px; }
.contact-info .value { flex: 1; color: var(--text); }

/* Forms */
.form-card { background: var(--white); padding: 32px; border-radius: var(--radius); box-shadow: var(--shadow); border: 1px solid var(--border); }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; margin-bottom: 6px; font-size: 14px; color: var(--text); font-weight: 500; }
.form-group input, .form-group select, .form-group textarea {
  width: 100%; padding: 12px 14px; border: 1px solid var(--border); border-radius: var(--radius);
  font-size: 15px; color: var(--text); background: var(--bg); transition: var(--transition);
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus {
  outline: none; border-color: var(--primary); background: var(--white);
}
.form-group textarea { min-height: 120px; resize: vertical; }
.form-row { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }

/* Page banner (sub pages) */
.page-banner {
  position: relative; padding: 100px 0 70px; text-align: center; color: var(--white);
  background: linear-gradient(135deg, rgba(21,57,91,0.95), rgba(51,56,61,0.92)), url('../images/banner.svg');
  background-size: cover; background-position: center;
}
.page-banner h1 { margin: 0 0 10px; font-size: 32px; }
.page-banner p { margin: 0; opacity: 0.9; }

/* Footer */
.site-footer { background: var(--secondary); color: rgba(255,255,255,0.85); padding: 50px 0 24px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr; gap: 40px; }
.footer-col h4 { margin: 0 0 14px; color: var(--white); font-size: 18px; }
.footer-col p { margin: 0 0 8px; font-size: 14px; }
.footer-bottom { text-align: center; margin-top: 36px; padding-top: 20px; border-top: 1px solid rgba(255,255,255,0.1); font-size: 14px; color: rgba(255,255,255,0.6); }

/* Tables / lists */
ul.clean { margin: 0; padding-left: 20px; color: var(--text-light); }
ul.clean li { margin-bottom: 10px; }

/* Product page category */
.category-section { margin-bottom: 50px; }
.category-title { font-size: 22px; color: var(--primary); border-left: 4px solid var(--primary); padding-left: 14px; margin: 0 0 20px; }
.category-desc { color: var(--text-light); margin: 0 0 18px; font-size: 15px; }
.product-label { display: inline-block; margin-top: 10px; padding: 3px 10px; background: var(--bg); color: var(--text-light); font-size: 12px; border-radius: 3px; }

/* Damage cards */
.damage-card { background: var(--white); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; box-shadow: var(--shadow); }
.damage-card h4 { color: var(--primary); margin: 0 0 12px; font-size: 17px; }
.damage-card p { margin: 0 0 6px; font-size: 14px; color: var(--text-light); }
.damage-card strong { color: var(--text); }

/* Responsive */
@media (max-width: 1024px) {
  .grid-5 { grid-template-columns: repeat(3, 1fr); }
  .grid-4 { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 768px) {
  .header-inner { height: 66px; }
  .logo img { height: 40px; }
  .mobile-menu-btn { display: block; }
  .nav-links {
    position: absolute; top: 66px; left: 0; right: 0; background: var(--white);
    flex-direction: column; align-items: stretch; padding: 10px 20px; gap: 0;
    border-bottom: 1px solid var(--border); box-shadow: 0 8px 20px rgba(0,0,0,0.06);
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 0; border-bottom: 1px solid var(--border); border-radius: 0; }
  .nav-links a:last-child { border-bottom: 0; }

  .hero { height: 420px; }
  .hero h1 { font-size: 24px; }
  .hero p { font-size: 15px; }

  .section { padding: 46px 0; }
  .section-title { font-size: 23px; }

  .grid-2, .grid-3, .grid-4, .grid-5 { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; gap: 24px; }
  .knowledge-item { flex-direction: column; }

  .page-banner { padding: 70px 0 50px; }
  .page-banner h1 { font-size: 24px; }
}