:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f5f5f7;
  --bg-dark: #1d1d1f;
  --bg-darker: #000000;
  --text-primary: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #86868b;
  --text-light: #f5f5f7;
  --text-light-secondary: #86868b;
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --accent-dark: #2997ff;
  --border: #d2d2d7;
  --border-dark: #424245;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --font-sans: -apple-system, "SF Pro Display", "SF Pro Text", "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--text-primary);
  background: var(--bg-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a { color: inherit; text-decoration: none; }
button { font-family: inherit; }

.container { max-width: 1080px; margin: 0 auto; padding: 0 22px; }

.section { padding: 100px 0; }
.section-gray { background: var(--bg-secondary); }
.section-dark { background: var(--bg-dark); color: var(--text-light); }
.section-dark .section-title { color: var(--text-light); }
.section-dark .section-subtitle { color: var(--text-light-secondary); }

.section-header { text-align: center; margin-bottom: 64px; }
.section-number { font-size: 14px; font-weight: 500; color: var(--accent); margin-bottom: 12px; letter-spacing: 0.02em; }
.section-number.dark { color: var(--accent-dark); }
.section-title { font-size: clamp(28px, 4vw, 40px); font-weight: 600; letter-spacing: -0.02em; margin-bottom: 16px; }
.section-subtitle { font-size: 18px; color: var(--text-secondary); max-width: 600px; margin: 0 auto; }

.grid { display: grid; gap: 24px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--bg-primary);
  border: 1px solid rgba(0,0,0,0.06);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}
.card:hover { transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.06); }
.card-icon { color: var(--accent); margin-bottom: 16px; }
.card-title { font-size: 18px; font-weight: 500; margin-bottom: 8px; }
.card-desc { font-size: 15px; color: var(--text-secondary); line-height: 1.5; }

.service-card .card-output {
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid rgba(0,0,0,0.06);
}
.output-label { display: block; font-size: 12px; font-weight: 500; color: var(--text-tertiary); margin-bottom: 4px; }
.output-text { font-size: 14px; color: var(--text-primary); }

.article-card { display: flex; flex-direction: column; background: var(--bg-primary); }
.article-cat { display: inline-block; align-self: flex-start; font-size: 12px; font-weight: 500; color: var(--accent); background: rgba(0,113,227,0.08); padding: 4px 12px; border-radius: 980px; margin-bottom: 14px; }
.article-link { margin-top: 16px; font-size: 14px; font-weight: 500; color: var(--accent); }
.article-card:hover .article-link { text-decoration: underline; }
.insights-note { text-align: center; margin-top: 40px; font-size: 15px; color: var(--text-secondary); }

.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(255,255,255,0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid rgba(0,0,0,0.08);
  transition: background 0.3s;
}
.nav.scrolled { background: rgba(255,255,255,0.9); }
.nav-container { max-width: 1080px; margin: 0 auto; padding: 0 22px; height: 52px; display: flex; align-items: center; justify-content: space-between; }
.nav-logo { font-size: 17px; font-weight: 600; letter-spacing: -0.01em; }
.nav-links { display: flex; gap: 28px; }
.nav-links a { font-size: 14px; color: var(--text-secondary); transition: color 0.2s; }
.nav-links a:hover { color: var(--text-primary); }
.nav-actions { display: flex; align-items: center; gap: 12px; }

.lang-toggle {
  background: none; border: 1px solid var(--border); border-radius: 980px;
  padding: 5px 12px; font-size: 13px; cursor: pointer; display: flex; align-items: center; gap: 4px;
  transition: border-color 0.2s;
}
.lang-toggle:hover { border-color: var(--text-secondary); }
.lang-zh, .lang-en { color: var(--text-tertiary); transition: color 0.2s; }
.lang-zh.active { color: var(--accent); font-weight: 500; }
.lang-en.active { color: var(--accent); font-weight: 500; }
.lang-sep { color: var(--text-tertiary); }

.nav-mobile-toggle { display: none; flex-direction: column; justify-content: center; gap: 5px; width: 30px; height: 30px; background: none; border: none; cursor: pointer; padding: 0; }
.nav-mobile-toggle span { display: block; width: 22px; height: 2px; background: var(--text-primary); border-radius: 2px; transition: all 0.3s; }
.nav-mobile-toggle.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-mobile-toggle.active span:nth-child(2) { opacity: 0; }
.nav-mobile-toggle.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.nav-mobile-menu { display: none; flex-direction: column; padding: 12px 22px 20px; gap: 4px; background: rgba(255,255,255,0.98); backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px); border-bottom: 1px solid rgba(0,0,0,0.08); }
.nav-mobile-menu.open { display: flex; }
.nav-mobile-menu a { padding: 12px 0; font-size: 16px; color: var(--text-primary); border-bottom: 1px solid rgba(0,0,0,0.04); }

.hero {
  min-height: 90vh; display: flex; align-items: center; justify-content: center; text-align: center;
  padding: 80px 22px 60px; position: relative;
  background:
    radial-gradient(ellipse 80% 60% at center, rgba(255,255,255,0) 0%, rgba(245,245,247,0.4) 100%),
    linear-gradient(rgba(0,0,0,0.012) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0,0,0,0.012) 1px, transparent 1px);
  background-size: 100% 100%, 44px 44px, 44px 44px;
}
.hero-content { max-width: 820px; }
.hero-title { font-size: clamp(32px, 5vw, 56px); font-weight: 600; line-height: 1.12; letter-spacing: -0.02em; margin-bottom: 24px; }
.hero-subtitle { font-size: clamp(17px, 2vw, 21px); color: var(--text-secondary); line-height: 1.5; max-width: 640px; margin: 0 auto 40px; }
.hero-cta { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

.btn {
  display: inline-block; padding: 12px 28px; border-radius: 980px; font-size: 16px; font-weight: 400;
  text-decoration: none; cursor: pointer; border: none; transition: all 0.2s;
}
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: var(--accent-hover); }
.btn-secondary { background: transparent; color: var(--accent); border: 1px solid var(--accent); }
.btn-secondary:hover { background: var(--accent); color: #fff; }
.btn-light { background: var(--text-light); color: var(--bg-dark); width: 100%; }
.btn-light:hover { background: #fff; }

.scroll-indicator { position: absolute; bottom: 40px; left: 50%; transform: translateX(-50%); color: var(--text-tertiary); animation: bounce 2.2s infinite; }
@keyframes bounce { 0%,100% { transform: translateX(-50%) translateY(0); } 50% { transform: translateX(-50%) translateY(8px); } }
@media (prefers-reduced-motion: reduce) { .scroll-indicator { animation: none; } }

.why-item { text-align: center; }
.why-number { font-size: 14px; font-weight: 500; color: var(--accent-dark); margin-bottom: 12px; }
.why-title { font-size: 20px; font-weight: 500; color: var(--text-light); margin-bottom: 8px; }
.why-desc { font-size: 14px; color: var(--text-light-secondary); line-height: 1.5; }

.process-steps { display: flex; justify-content: space-between; gap: 16px; position: relative; }
.process-steps::before { content: ''; position: absolute; top: 20px; left: 8%; right: 8%; height: 1px; background: var(--border); z-index: 0; }
.process-step { flex: 1; text-align: center; position: relative; z-index: 1; }
.step-number { width: 40px; height: 40px; border-radius: 50%; background: var(--bg-primary); border: 1px solid var(--border); display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: 600; color: var(--accent); margin: 0 auto 16px; }
.step-title { font-size: 15px; font-weight: 500; margin-bottom: 6px; }
.step-desc { font-size: 13px; color: var(--text-secondary); line-height: 1.4; }

.cases-list { max-width: 760px; margin: 0 auto; }
.case-card { background: var(--bg-primary); border: 1px solid rgba(0,0,0,0.08); border-radius: var(--radius-lg); overflow: hidden; margin-bottom: 16px; }
.case-header { width: 100%; padding: 24px 32px; background: none; border: none; cursor: pointer; display: flex; align-items: center; gap: 16px; text-align: left; transition: background 0.2s; }
.case-header:hover { background: var(--bg-secondary); }
.case-tag { font-size: 12px; color: var(--accent); font-weight: 500; white-space: nowrap; }
.case-title { font-size: 18px; font-weight: 500; flex: 1; }
.case-toggle { font-size: 24px; color: var(--text-tertiary); transition: transform 0.3s; }
.case-card.open .case-toggle { transform: rotate(45deg); }
.case-body { max-height: 0; overflow: hidden; transition: max-height 0.4s ease; }
.case-card.open .case-body { max-height: 600px; }
.case-body-inner { padding: 0 32px 28px; }
.case-row { padding: 14px 0; border-top: 1px solid rgba(0,0,0,0.06); }
.case-label { font-size: 12px; font-weight: 500; color: var(--text-tertiary); display: block; margin-bottom: 4px; }
.case-row p { font-size: 15px; color: var(--text-primary); line-height: 1.6; }

.about-content { max-width: 720px; margin: 0 auto; }
.about-content p { font-size: 17px; color: var(--text-secondary); line-height: 1.7; margin-bottom: 20px; }

.resources-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; max-width: 720px; margin: 32px auto 0; }
.resource-item { display: flex; align-items: center; gap: 10px; font-size: 15px; color: var(--text-primary); }
.resource-dot { width: 6px; height: 6px; border-radius: 50%; background: var(--accent); flex-shrink: 0; }

.contact-grid { max-width: 840px; margin: 0 auto; display: grid; grid-template-columns: 1fr 1.4fr; gap: 48px; align-items: start; }
.contact-info { display: flex; flex-direction: column; gap: 24px; }
.contact-method { display: flex; flex-direction: column; gap: 4px; }
.contact-label { font-size: 12px; font-weight: 500; color: var(--text-light-secondary); }
.contact-method a, .contact-method span { font-size: 16px; color: var(--text-light); }
.contact-method a:hover { color: var(--accent-dark); }

.brand-logo { height: 24px; width: auto; display: block; }
.brand-logo-footer { height: 28px; }
.wechat-qr { width: 120px; height: 120px; border-radius: var(--radius-sm); background: #fff; padding: 6px; cursor: zoom-in; }

.lightbox { position: fixed; inset: 0; z-index: 2000; background: rgba(0,0,0,0.85); display: flex; align-items: center; justify-content: center; opacity: 0; visibility: hidden; transition: opacity 0.25s ease; cursor: zoom-out; }
.lightbox.open { opacity: 1; visibility: visible; }
.lightbox img { max-width: 80vw; max-height: 80vh; width: 320px; border-radius: var(--radius-md); background: #fff; padding: 12px; box-shadow: 0 20px 60px rgba(0,0,0,0.5); }

.contact-form { display: flex; flex-direction: column; gap: 14px; }
.contact-form input, .contact-form textarea, .contact-form select {
  background: rgba(255,255,255,0.06); border: 1px solid rgba(255,255,255,0.12); border-radius: var(--radius-sm);
  padding: 14px 16px; font-size: 15px; color: var(--text-light); font-family: inherit; transition: border-color 0.2s;
}
.contact-form input:focus, .contact-form textarea:focus, .contact-form select:focus { outline: none; border-color: var(--accent-dark); }
.contact-form input::placeholder, .contact-form textarea::placeholder { color: rgba(255,255,255,0.35); }
.contact-form select option { background: var(--bg-dark); color: var(--text-light); }
.honeypot { position: absolute; left: -9999px; }
.form-success { display: none; text-align: center; padding: 40px; }
.form-success p { font-size: 18px; color: var(--text-light); }

.footer { background: var(--bg-darker); color: var(--text-light-secondary); padding: 48px 0 24px; }
.footer-container { display: flex; justify-content: space-between; align-items: flex-start; flex-wrap: wrap; gap: 32px; }
.footer-logo { font-size: 18px; font-weight: 600; color: var(--text-light); margin-bottom: 4px; }
.footer-tagline { font-size: 13px; }
.footer-links { display: flex; gap: 24px; }
.footer-links a { font-size: 14px; color: var(--text-light-secondary); transition: color 0.2s; }
.footer-links a:hover { color: var(--text-light); }
.footer-bottom { max-width: 1080px; margin: 32px auto 0; padding: 20px 22px 0; border-top: 1px solid rgba(255,255,255,0.08); font-size: 12px; text-align: center; }

.fade-in { opacity: 0; transform: translateY(30px); transition: opacity 0.7s ease, transform 0.7s ease; }
.fade-in.visible { opacity: 1; transform: translateY(0); }
.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }
@media (prefers-reduced-motion: reduce) { .fade-in { opacity: 1; transform: none; transition: none; } }

@media (max-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .resources-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-mobile-toggle { display: flex; }
  .grid-3, .grid-4, .resources-grid { grid-template-columns: 1fr; }
  .section { padding: 64px 0; }
  .section-header { margin-bottom: 40px; }
  .process-steps { flex-direction: column; gap: 32px; }
  .process-steps::before { display: none; }
  .contact-grid { grid-template-columns: 1fr; gap: 32px; }
  .footer-container { flex-direction: column; }
  .hero { min-height: 80vh; }
}