/* ===== Reset & Variables ===== */
* { margin: 0; padding: 0; box-sizing: border-box; }

:root {
  --color-primary: #0B3D66;
  --color-primary-dark: #082944;
  --color-accent: #E8622C;
  --color-accent-dark: #c94f1e;
  --color-bg: #F5F6F8;
  --color-white: #FFFFFF;
  --color-text: #222222;
  --color-text-light: #5A6472;
  --max-width: 1160px;
  --radius: 8px;
  --transition: 0.3s ease;
}

html { scroll-behavior: smooth; }

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

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 20px; }
img { max-width: 100%; display: block; }
a { text-decoration: none; color: inherit; }
ul { list-style: none; }

/* ===== Header / Nav ===== */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  background: rgba(11, 61, 102, 0.95);
  z-index: 1000;
}
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.logo { font-size: 20px; font-weight: bold; color: var(--color-white); }
.logo span { color: var(--color-accent); margin-left: 4px; }

.main-nav { display: flex; gap: 28px; }
.nav-link {
  color: var(--color-white);
  font-size: 15px;
  padding: 8px 0;
  border-bottom: 2px solid transparent;
  transition: border-color var(--transition), color var(--transition);
}
.nav-link:hover, .nav-link.active { border-color: var(--color-accent); color: var(--color-accent); }

.phone-btn {
  background: var(--color-accent);
  color: var(--color-white);
  padding: 8px 16px;
  border-radius: 999px;
  font-size: 14px;
  white-space: nowrap;
  transition: background var(--transition);
}
.phone-btn:hover { background: var(--color-accent-dark); }

.nav-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: none; cursor: pointer; padding: 8px; }
.nav-toggle span { width: 24px; height: 2px; background: var(--color-white); }

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  padding: 12px 32px;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: bold;
  transition: transform var(--transition), background var(--transition);
}
.btn:hover { transform: translateY(-2px); }
.btn-accent { background: var(--color-accent); color: var(--color-white); }
.btn-accent:hover { background: var(--color-accent-dark); }
.btn-outline { border: 2px solid var(--color-white); color: var(--color-white); }
.btn-outline:hover { background: var(--color-white); color: var(--color-primary); }

/* ===== Section shell ===== */
.section { padding: 90px 0; }
.section-alt { background: var(--color-bg); }
.section-title {
  font-size: 30px;
  color: var(--color-primary);
  text-align: center;
  margin-bottom: 16px;
  position: relative;
  padding-bottom: 16px;
}
.section-title::after {
  content: "";
  position: absolute;
  bottom: 0; left: 50%;
  transform: translateX(-50%);
  width: 60px; height: 4px;
  background: var(--color-accent);
  border-radius: 2px;
}
.section-subtitle { text-align: center; color: var(--color-text-light); max-width: 760px; margin: 0 auto 48px; }

/* ===== Footer & back-to-top ===== */
.site-footer { background: var(--color-primary-dark); color: #C9D3DE; text-align: center; padding: 32px 0; font-size: 14px; }
.site-footer a { color: #C9D3DE; }
.site-footer a:hover { color: var(--color-accent); }

.back-to-top {
  position: fixed;
  right: 24px; bottom: 24px;
  width: 44px; height: 44px;
  background: var(--color-accent);
  color: var(--color-white);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all var(--transition);
  z-index: 999;
}
.back-to-top.visible { opacity: 1; visibility: visible; transform: translateY(0); }

/* ===== Responsive nav ===== */
@media (max-width: 900px) {
  .main-nav, .phone-btn { display: none; }
  .nav-toggle { display: flex; }
  .main-nav.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: var(--color-primary-dark);
    padding: 16px 20px;
    gap: 0;
  }
  .main-nav.open .nav-link { padding: 12px 0; border-bottom: 1px solid rgba(255,255,255,0.1); }
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary)),
              url("../images/site-03.jpg") center/cover no-repeat;
  background-blend-mode: multiply;
}
.hero-overlay { position: absolute; inset: 0; background: rgba(8, 41, 68, 0.55); }
.hero-inner { position: relative; z-index: 1; text-align: center; color: var(--color-white); padding-top: 64px; }
.hero h1 { font-size: 40px; margin-bottom: 16px; }
.hero-tagline { font-size: 18px; color: #E5EAF0; margin-bottom: 32px; letter-spacing: 1px; }
.hero-stats { display: flex; justify-content: center; gap: 48px; margin-bottom: 40px; flex-wrap: wrap; }
.stat { display: flex; flex-direction: column; align-items: center; }
.stat strong { font-size: 32px; color: var(--color-accent); }
.stat span { font-size: 14px; color: #C9D3DE; margin-top: 4px; }
.hero-actions { display: flex; justify-content: center; gap: 16px; }

@media (max-width: 900px) {
  .hero h1 { font-size: 28px; }
  .hero-stats { gap: 28px; }
}

/* ===== About ===== */
.about-text { max-width: 860px; margin: 0 auto 24px; color: var(--color-text-light); font-size: 16px; }

.stat-cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; margin-top: 48px; }
.stat-card {
  background: var(--color-bg);
  border-top: 3px solid var(--color-accent);
  border-radius: var(--radius);
  padding: 28px 16px;
  text-align: center;
}
.stat-card strong { display: block; font-size: 26px; color: var(--color-primary); margin-bottom: 8px; }
.stat-card span { font-size: 14px; color: var(--color-text-light); }

/* ===== Services ===== */
.service-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.service-card {
  background: var(--color-white);
  border: 1px solid #E3E7EC;
  border-radius: var(--radius);
  padding: 24px 16px;
  text-align: center;
  font-size: 16px;
  font-weight: bold;
  color: var(--color-primary);
  transition: transform var(--transition), box-shadow var(--transition);
}
.service-card:hover { transform: translateY(-4px); box-shadow: 0 8px 20px rgba(11,61,102,0.12); color: var(--color-accent); }

@media (max-width: 900px) {
  .stat-cards, .service-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 560px) {
  .stat-cards, .service-grid { grid-template-columns: 1fr; }
}

/* ===== Project list ===== */
.project-list { max-width: 860px; margin: 0 auto 56px; }
.project-list li {
  padding: 16px 0 16px 28px;
  border-bottom: 1px solid #E3E7EC;
  position: relative;
  color: var(--color-text-light);
}
.project-list li::before {
  content: "";
  position: absolute;
  left: 0; top: 24px;
  width: 10px; height: 10px;
  background: var(--color-accent);
  border-radius: 50%;
}

/* ===== Gallery ===== */
.gallery { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.gallery-item { position: relative; overflow: hidden; border-radius: var(--radius); aspect-ratio: 4/3; cursor: pointer; }
.gallery-item img { width: 100%; height: 100%; object-fit: cover; transition: transform var(--transition); }
.gallery-item:hover img { transform: scale(1.08); }

@media (max-width: 900px) {
  .gallery { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 560px) {
  .gallery { grid-template-columns: 1fr; }
}

/* ===== Qualifications ===== */
.cert-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.cert-card {
  background: var(--color-white);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  text-align: center;
}
.cert-card img { width: 100%; }
.cert-card figcaption { padding: 16px; font-size: 15px; color: var(--color-primary); font-weight: bold; }

/* ===== Contact ===== */
.contact-info { max-width: 640px; margin: 0 auto; text-align: center; font-size: 16px; }
.contact-info p { margin-bottom: 12px; }
.contact-info a { color: var(--color-accent); font-weight: bold; }

@media (max-width: 900px) {
  .cert-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 560px) {
  .cert-grid { grid-template-columns: 1fr; }
}

/* ===== Fade-in animation ===== */
.fade-in { opacity: 0; transform: translateY(24px); transition: opacity 0.6s ease, transform 0.6s ease; }
.fade-in.in-view { opacity: 1; transform: translateY(0); }

/* ===== Lightbox ===== */
.lightbox-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.85);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  flex-direction: column;
}
.lightbox-overlay.open { display: flex; }
.lightbox-overlay img { max-width: 90vw; max-height: 80vh; border-radius: 4px; }
.lightbox-caption { color: var(--color-white); margin-top: 16px; font-size: 16px; }
.lightbox-close {
  position: absolute;
  top: 24px; right: 32px;
  color: var(--color-white);
  font-size: 32px;
  cursor: pointer;
  background: none;
  border: none;
}

/* ===== Leader page ===== */
.leader-profile {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 48px;
  align-items: start;
  margin-top: 48px;
}

.leader-photo-col { text-align: center; }
.leader-avatar {
  width: 100%;
  aspect-ratio: 3/4;
  object-fit: cover;
  border-radius: var(--radius);
  box-shadow: 0 8px 24px rgba(0,0,0,0.12);
  margin-bottom: 20px;
}
.leader-photo-col h2 { color: var(--color-primary); font-size: 22px; margin-bottom: 4px; }
.leader-photo-col .leader-title { color: var(--color-accent); font-size: 15px; font-weight: bold; margin-bottom: 20px; }

.leader-basic { text-align: left; background: var(--color-bg); border-radius: var(--radius); padding: 8px 20px; }
.leader-basic li { padding: 10px 0; border-bottom: 1px solid #E3E7EC; font-size: 14px; color: var(--color-text); }
.leader-basic li:last-child { border-bottom: none; }
.leader-basic li strong { color: var(--color-primary); }

.leader-bio p { color: var(--color-text-light); margin-bottom: 20px; font-size: 15.5px; line-height: 1.85; }
.leader-bio p strong { color: var(--color-primary); }

@media (max-width: 700px) {
  .leader-profile { grid-template-columns: 1fr; }
  .leader-photo-col { max-width: 280px; margin: 0 auto; }
}