/* RESET & base */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body { font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif; background: #f9fafc; color: #1a1f2b; line-height: 1.5; transition: background 0.3s, color 0.3s; }
.container { max-width: 1280px; margin: 0 auto; padding: 0 1.5rem; }
a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; height: auto; }
ul { list-style: none; }
/* brand colors */
:root { --brand-primary: #003057; --brand-accent: #FFD100; --brand-light: #e6f0fa; --glass-bg: rgba(255,255,255,0.7); --shadow-sm: 0 8px 20px rgba(0,0,0,0.05); --radius-lg: 32px; --radius-card: 20px; }
.dark { --brand-primary: #0b2a44; --brand-light: #1e2a3a; --glass-bg: rgba(20,30,45,0.8); background: #111827; color: #e5e7eb; }
/* header */
.header { position: sticky; top: 0; z-index: 100; backdrop-filter: blur(16px); background: var(--glass-bg); border-bottom: 1px solid rgba(0,48,87,0.1); padding: 0.6rem 0; transition: background 0.3s; }
.header .container { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.logo svg { width: 48px; height: 48px; }
.nav { display: flex; gap: 1.2rem; font-weight: 500; }
.nav a { padding: 0.4rem 0; border-bottom: 2px solid transparent; transition: 0.2s; }
.nav a:hover, .nav a.active { border-bottom-color: var(--brand-accent); color: var(--brand-primary); }
.menu-toggle { display: none; background: none; border: none; font-size: 1.8rem; cursor: pointer; color: inherit; }
.dark-toggle { background: none; border: 1px solid var(--brand-primary); border-radius: 40px; padding: 0.3rem 0.8rem; font-size: 0.9rem; cursor: pointer; }
/* hero */
.hero { background: linear-gradient(145deg, #003057 0%, #1b4f78 100%); color: white; padding: 4rem 0 3.5rem; border-radius: 0 0 3rem 3rem; box-shadow: var(--shadow-sm); margin-bottom: 2.5rem; position: relative; overflow: hidden; }
.hero h1 { font-size: clamp(2.2rem, 6vw, 3.8rem); font-weight: 700; line-height: 1.2; max-width: 720px; }
.hero p { font-size: 1.2rem; margin: 1.5rem 0 2rem; opacity: 0.9; max-width: 600px; }
.hero-btn { display: inline-block; background: var(--brand-accent); color: #003057; padding: 0.8rem 2.5rem; border-radius: 60px; font-weight: 700; font-size: 1.1rem; transition: 0.2s; }
.hero-btn:hover { transform: scale(1.02); box-shadow: 0 8px 20px rgba(255,209,0,0.3); }
/* sections */
section { padding: 3rem 0; }
.section-title { font-size: 2rem; font-weight: 600; margin-bottom: 2rem; border-left: 6px solid var(--brand-accent); padding-left: 1rem; }
.card { background: white; border-radius: var(--radius-card); padding: 1.8rem; box-shadow: var(--shadow-sm); transition: transform 0.2s, box-shadow 0.3s; backdrop-filter: blur(4px); background: var(--glass-bg); }
.dark .card { background: rgba(30,40,55,0.7); box-shadow: 0 8px 20px rgba(0,0,0,0.4); }
.card:hover { transform: translateY(-4px); box-shadow: 0 20px 30px rgba(0,0,0,0.08); }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 2rem; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 2rem; }
.flex-center { display: flex; align-items: center; gap: 1.2rem; flex-wrap: wrap; }
/* faq */
.faq-item { border-bottom: 1px solid rgba(0,0,0,0.05); padding: 1rem 0; }
.faq-question { font-weight: 600; cursor: pointer; display: flex; justify-content: space-between; align-items: center; }
.faq-answer { max-height: 0; overflow: hidden; transition: 0.3s; padding-top: 0.2rem; }
.faq-item.open .faq-answer { max-height: 300px; }
.howto-step { margin: 1.2rem 0; padding-left: 1.5rem; border-left: 3px solid var(--brand-accent); }
/* footer */
.footer { background: #0b1a2b; color: #ccd9e6; padding: 2.5rem 0 1.5rem; margin-top: 3rem; border-radius: 2rem 2rem 0 0; }
.footer a { color: #b0c7db; }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px,1fr)); gap: 2rem; }
/* animation classes */
.fade-up { opacity: 0; transform: translateY(20px); transition: 0.6s; }
.fade-up.visible { opacity: 1; transform: translateY(0); }
.count-up { display: inline-block; }
/* mobile */
@media (max-width: 768px) {
  .nav { display: none; flex-direction: column; width: 100%; margin-top: 1rem; gap: 0.8rem; }
  .nav.open { display: flex; }
  .menu-toggle { display: block; }
  .hero { padding: 2.5rem 0 2rem; }
}
/* breadcrumb */
.breadcrumb { display: flex; gap: 0.5rem; font-size: 0.9rem; padding: 0.8rem 0; color: #3a4b5e; }
.dark .breadcrumb { color: #b0c7db; }
/* 轮播 */
.carousel { overflow: hidden; position: relative; width: 100%; border-radius: 24px; }
.carousel-inner { display: flex; transition: transform 0.5s ease; }
.carousel-item { min-width: 100%; padding: 0 0.5rem; }
.carousel-controls { display: flex; justify-content: center; gap: 1rem; margin-top: 1rem; }