/* ===== SHARED STYLES ===== */
/* Include this file in all pages via <link rel="stylesheet" href="shared.css" /> */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --blue-900: #091F2F;
  --blue-800: #0D2F47;
  --blue-700: #144A6C;
  --blue-600: #198ACD;
  --blue-500: #2D9AD8;
  --blue-400: #54B3E3;
  --blue-300: #8ECBEE;
  --blue-200: #C1E1F5;
  --blue-100: #DFEEF8;
  --blue-50:  #EDF5FB;
  --red:      #C00000;
  --red-light: #D33;
  --white:   #FFFFFF;
  --off-white: #F8F9FB;
  --gray-100: #EEF1F5;
  --gray-300: #C8CDD5;
  --gray-500: #7D8590;
  --gray-700: #3B4451;
  --text:    #1A2535;
  --heading: 'Inter', -apple-system, 'Microsoft YaHei', '微软雅黑', sans-serif;
  --sans:    'Inter', -apple-system, 'Microsoft YaHei', '微软雅黑', sans-serif;
  --shadow-sm: 0 2px 8px rgba(15,43,70,0.06);
  --shadow-md: 0 8px 30px rgba(15,43,70,0.10);
  --shadow-lg: 0 20px 60px rgba(15,43,70,0.14);
  --radius: 6px;
  --radius-lg: 14px;
  --transition: 0.3s cubic-bezier(0.4,0,0.2,1);
}
html { scroll-behavior: smooth; }
body { font-family: var(--sans); color: var(--text); background: var(--white); line-height: 1.6; -webkit-font-smoothing: antialiased; }
a { color: inherit; }

/* TYPOGRAPHY */
h1, h2, h3, h4 { font-family: var(--heading); line-height: 1.25; }
h1 { font-size: clamp(2.2rem, 4.5vw, 3.8rem); font-weight: 700; letter-spacing: -0.02em; }
h2 { font-size: clamp(1.8rem, 3.5vw, 2.8rem); font-weight: 600; letter-spacing: -0.01em; }
h3 { font-size: clamp(1.15rem, 2vw, 1.5rem); font-weight: 600; }
h4 { font-size: 1rem; font-weight: 600; }
p  { font-size: 1rem; line-height: 1.75; color: var(--gray-700); }

/* LAYOUT */
.container { max-width: 1160px; margin: 0 auto; padding: 0 2rem; }
.section { padding: 90px 0; }
.section-label { font-family: var(--sans); font-size: 0.72rem; font-weight: 700; letter-spacing: 0.2em; text-transform: uppercase; color: var(--blue-500); margin-bottom: 1rem; }
.section-title { margin-bottom: 1rem; }
.section-subtitle { font-size: 1.08rem; color: var(--gray-500); max-width: 600px; }
.text-center { text-align: center; }
.text-center .section-subtitle { margin: 0 auto 2.5rem; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 3.5rem; align-items: center; }
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 2rem; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1.5rem; }

/* BUTTONS */
.btn {
  display: inline-flex; align-items: center; gap: 0.5rem;
  padding: 0.85rem 2rem; font-size: 0.88rem; font-weight: 600;
  letter-spacing: 0.03em; text-decoration: none;
  border-radius: var(--radius); transition: var(--transition);
  cursor: pointer; border: 2px solid transparent;
}
.btn-primary { background: var(--blue-600); color: var(--white); }
.btn-primary:hover { background: var(--blue-700); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-red { background: var(--red); color: var(--white); }
.btn-red:hover { background: var(--red-light); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-outline { background: transparent; color: var(--white); border-color: rgba(255,255,255,0.45); }
.btn-outline:hover { background: rgba(255,255,255,0.1); border-color: var(--white); }
.btn-outline-blue { background: transparent; color: var(--blue-600); border-color: var(--blue-600); }
.btn-outline-blue:hover { background: var(--blue-600); color: var(--white); }

/* NAVIGATION */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  padding: 1rem 0; transition: var(--transition);
  background: transparent;
}
.nav-page {
  background: var(--white);
  box-shadow: 0 1px 20px rgba(15,43,70,0.06);
  padding: 0.7rem 0;
}
.nav-page .nav-links a { color: var(--gray-700); }
.nav-page .nav-links a:hover,
.nav-page .nav-links a.active { color: var(--blue-600); }
.nav-page .nav-cta { background: var(--blue-600); color: var(--white); }
.nav.scrolled {
  background: rgba(255,255,255,0.97); backdrop-filter: blur(12px);
  padding: 0.7rem 0; box-shadow: 0 1px 20px rgba(15,43,70,0.08);
}
.nav.scrolled .nav-links a { color: var(--gray-700); }
.nav.scrolled .nav-links a:hover { color: var(--blue-600); }
.nav.scrolled .nav-cta { background: var(--blue-600); color: var(--white); }
.nav-inner { display: flex; align-items: center; justify-content: space-between; }
.nav-logo { display: flex; align-items: center; gap: 0.7rem; text-decoration: none; }
.nav-logo-icon {
  height: 40px; width: auto; display: flex; align-items: center;
}
.nav-logo-icon img { height: 100%; width: auto; }
.nav-logo-text { font-family: var(--heading); font-size: 1.1rem; color: var(--blue-900); font-weight: 600; letter-spacing: 0.02em; }
.nav-links { display: flex; align-items: center; gap: 1.8rem; list-style: none; }
.nav-links a { font-size: 0.85rem; font-weight: 500; letter-spacing: 0.04em; color: var(--gray-700); text-decoration: none; transition: color var(--transition); }
.nav-links a:hover { color: var(--blue-600); }
.nav-links a.active { color: var(--blue-600); font-weight: 600; }
.nav-cta { font-size: 0.82rem; padding: 0.55rem 1.3rem; }

/* LANGUAGE TOGGLE */
.lang-toggle {
  font-size: 0.72rem; font-weight: 700; letter-spacing: 0.06em;
  color: var(--gray-700); background: var(--white);
  border: 1px solid var(--blue-200); border-radius: var(--radius);
  padding: 0.4rem 0.8rem; cursor: pointer; transition: var(--transition);
  font-family: var(--sans);
}
.lang-toggle:hover { background: var(--blue-50); color: var(--blue-700); border-color: var(--blue-400); }
.lang-zh { display: none; }

/* PAGE HERO BANNER */
.page-hero {
  padding: 140px 0 70px;
  background: linear-gradient(160deg, var(--blue-800) 0%, var(--blue-600) 100%);
  position: relative; overflow: hidden;
}
.page-hero::before {
  content: ''; position: absolute; inset: 0;
  background-image: radial-gradient(rgba(255,255,255,0.04) 1px, transparent 1px);
  background-size: 24px 24px;
}
.page-hero .container { position: relative; z-index: 1; }
.page-hero .section-label { color: var(--blue-400); }
.page-hero h1 { color: var(--white); margin-bottom: 0.8rem; }
.page-hero .section-subtitle { color: rgba(255,255,255,0.7); }

/* FOOTER */
.footer { background: var(--blue-900); padding: 3rem 0 2rem; }
.footer-inner { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 1.5rem; padding-bottom: 2rem; border-bottom: 1px solid rgba(255,255,255,0.08); }
.footer-tagline { font-size: 0.82rem; color: rgba(255,255,255,0.4); margin-top: 0.3rem; margin-left: 0.5rem; }
.footer-links { display: flex; gap: 2rem; list-style: none; }
.footer-links a { font-size: 0.82rem; color: rgba(255,255,255,0.45); text-decoration: none; transition: color var(--transition); }
.footer-links a:hover { color: var(--blue-400); }
.footer-bottom { display: flex; justify-content: space-between; align-items: center; margin-top: 2rem; flex-wrap: wrap; gap: 1rem; }
.footer-bottom p { font-size: 0.76rem; color: rgba(255,255,255,0.25); }
.footer-bottom a { color: var(--blue-300); text-decoration: none; }

/* ENTRANCE ANIMATIONS */
.fade-in { opacity: 0; transform: translateY(20px); transition: opacity 0.6s ease, transform 0.6s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }

/* RESPONSIVE */
@media (max-width: 1024px) {
  .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .section { padding: 60px 0; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .nav-links { display: none; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
  .page-hero { padding: 120px 0 50px; }
}