/* 灯语 AI — 高端浅色风 */
:root {
  --bg: #f7f8fa;
  --bg-elevated: #ffffff;
  --bg-card: #ffffff;
  --bg-muted: #f0f2f5;
  --text: #1d2129;
  --muted: #646a73;
  --primary: #3370ff;
  --primary-dark: #245bdb;
  --primary-glow: rgba(51, 112, 255, 0.22);
  --primary-soft: #eef3ff;
  --accent: #3370ff;
  --accent-soft: rgba(51, 112, 255, 0.08);
  --border: #e5e6eb;
  --border-hover: rgba(51, 112, 255, 0.35);
  --shadow: 0 8px 40px rgba(29, 33, 41, 0.08);
  --shadow-hover: 0 16px 48px rgba(29, 33, 41, 0.12);
  --radius: 16px;
  --max: 1140px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Noto Sans SC", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }
img { max-width: 100%; display: block; }

.mesh-bg {
  position: fixed; inset: 0; z-index: -1; pointer-events: none;
  background:
    radial-gradient(ellipse 70% 45% at 50% -10%, rgba(51, 112, 255, 0.07), transparent),
    radial-gradient(ellipse 50% 35% at 100% 20%, rgba(51, 112, 255, 0.04), transparent),
    var(--bg);
}

/* Header */
.header {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  padding: 1rem 1.5rem;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}
.brand {
  display: inline-flex; align-items: center; gap: 0.5rem;
  text-decoration: none; min-height: 36px;
}
.brand-logo {
  display: block; height: 32px; width: auto;
  max-width: 160px; object-fit: contain;
}
.brand-fallback {
  font-weight: 700; font-size: 1.15rem; letter-spacing: 0.04em;
  background: linear-gradient(135deg, var(--text) 20%, var(--primary));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
  display: none;
}
.nav { display: none; gap: 1.75rem; align-items: center; }
.nav a { color: var(--muted); text-decoration: none; font-weight: 500; font-size: 0.92rem; transition: color 0.2s; }
.nav a:hover { color: var(--text); }
.nav-toggle {
  border: 1px solid var(--border); background: var(--bg-elevated);
  color: var(--text); border-radius: 10px; padding: 0.4rem 0.65rem; cursor: pointer;
}
@media (min-width: 768px) {
  .nav { display: flex; }
  .nav-toggle { display: none; }
}
.header.is-open .nav {
  display: flex; flex-direction: column; align-items: flex-start; gap: 1rem;
  position: absolute; top: 100%; left: 0; right: 0;
  background: var(--bg-elevated); padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
}

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 0.75rem 1.5rem; border-radius: 999px;
  font-weight: 600; text-decoration: none; border: none; cursor: pointer;
  font-family: inherit; transition: all 0.25s ease;
}
.btn-sm { padding: 0.5rem 1.15rem; font-size: 0.88rem; }
.btn-lg { padding: 1rem 2rem; font-size: 1.05rem; }
.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff; box-shadow: 0 4px 16px var(--primary-glow);
}
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 8px 24px var(--primary-glow); }
.btn-outline {
  background: var(--bg-elevated); color: var(--text);
  border: 1px solid var(--border);
}
.btn-outline:hover { border-color: var(--border-hover); background: var(--primary-soft); }

/* Hero */
.hero {
  max-width: var(--max); margin: 0 auto;
  padding: 4rem 1.5rem 5rem;
  display: grid; gap: 3rem; align-items: center;
}
@media (min-width: 960px) {
  .hero { grid-template-columns: 1.05fr 0.95fr; padding-top: 5rem; min-height: 82vh; }
}
.pill {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-size: 0.78rem; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--primary); background: var(--primary-soft);
  padding: 0.35rem 0.9rem; border-radius: 999px;
  border: 1px solid rgba(51, 112, 255, 0.15);
}
.pill::before {
  content: ""; width: 6px; height: 6px; border-radius: 50%;
  background: var(--primary);
}
.hero h1 {
  font-size: clamp(2.25rem, 5.5vw, 3.5rem);
  font-weight: 700; line-height: 1.12; margin: 1.25rem 0 1rem;
  letter-spacing: -0.03em; color: var(--text);
}
.hero h1 em {
  font-style: normal;
  background: linear-gradient(135deg, var(--primary-dark), var(--primary));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.subtitle { color: var(--muted); font-size: 1.08rem; max-width: 34em; margin: 0 0 2rem; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 0.85rem; margin-bottom: 2.5rem; }
.trust-row {
  list-style: none; padding: 0; margin: 0;
  display: flex; flex-wrap: wrap; gap: 1.5rem;
  font-size: 0.88rem; color: var(--muted);
}
.trust-row li { display: flex; align-items: center; gap: 0.4rem; }
.trust-row li::before {
  content: "✓"; color: var(--primary); font-size: 0.75rem; font-weight: 700;
}

/* Stats bar */
.stats-bar {
  max-width: var(--max); margin: -2rem auto 0; padding: 0 1.5rem 3rem;
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 1rem;
}
@media (min-width: 640px) { .stats-bar { grid-template-columns: repeat(4, 1fr); } }
.stat-card {
  text-align: center; padding: 1.5rem 1rem;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
}
.stat-card strong {
  display: block; font-size: 1.75rem; font-weight: 700; color: var(--primary);
}
.stat-card span { font-size: 0.82rem; color: var(--muted); margin-top: 0.25rem; display: block; }

/* Chat */
.chat-window {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
  overflow: hidden;
}
.chat-head {
  padding: 1rem 1.25rem; font-weight: 600; font-size: 0.85rem;
  color: var(--muted); background: var(--bg-muted);
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center; gap: 0.5rem;
}
.chat-head::before {
  content: ""; width: 8px; height: 8px; border-radius: 50%;
  background: #22c55e;
}
.chat-body { padding: 1.25rem; min-height: 200px; max-height: 320px; overflow-y: auto; background: #fafbfc; }
.bubble {
  max-width: 90%; padding: 0.85rem 1.1rem; border-radius: 16px;
  font-size: 0.9rem; margin-bottom: 0.85rem; line-height: 1.55;
}
.bubble.user {
  margin-left: auto;
  background: var(--primary-soft);
  border: 1px solid rgba(51, 112, 255, 0.12);
  border-bottom-right-radius: 4px; color: var(--text);
}
.bubble.bot {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-bottom-left-radius: 4px; color: var(--muted);
}
.chat-input {
  display: flex; gap: 0.6rem; padding: 1rem; border-top: 1px solid var(--border);
  background: var(--bg-elevated);
}
.chat-input input {
  flex: 1; border: 1px solid var(--border); border-radius: 999px;
  padding: 0.65rem 1.15rem; font-family: inherit;
  background: var(--bg-muted); color: var(--text);
}
.chat-input input::placeholder { color: #a8abb2; }
.chat-input input:focus {
  outline: none; border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-soft);
}

/* Sections */
.section { max-width: var(--max); margin: 0 auto; padding: 5rem 1.5rem; }
.section-muted {
  background: var(--bg-muted);
  max-width: none;
}
.section-muted > * { max-width: var(--max); margin-left: auto; margin-right: auto; }
.section-head { margin-bottom: 2.5rem; text-align: center; max-width: 36em; margin-left: auto; margin-right: auto; }
.section-head .label {
  font-size: 0.75rem; font-weight: 600; letter-spacing: 0.15em;
  text-transform: uppercase; color: var(--primary); margin-bottom: 0.75rem;
}
.section-head h2 { font-size: clamp(1.75rem, 4vw, 2.25rem); margin: 0 0 0.75rem; font-weight: 700; color: var(--text); }
.section-head p { color: var(--muted); margin: 0; font-size: 1.02rem; }

.scene-grid { display: grid; gap: 1.25rem; }
@media (min-width: 640px) { .scene-grid { grid-template-columns: 1fr 1fr; } }
@media (min-width: 960px) { .scene-grid { grid-template-columns: repeat(4, 1fr); } }

.scene-card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.75rem 1.5rem;
  transition: all 0.3s ease; position: relative; overflow: hidden;
  box-shadow: 0 2px 8px rgba(29, 33, 41, 0.04);
}
.scene-card:hover {
  border-color: var(--border-hover); transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}
.scene-num {
  font-size: 0.72rem; font-weight: 700; color: var(--primary);
  letter-spacing: 0.1em; margin-bottom: 1rem;
}
.scene-card h3 { margin: 0 0 0.5rem; font-size: 1.1rem; }
.scene-card p { margin: 0; font-size: 0.9rem; color: var(--muted); }

.feature-list { display: grid; gap: 1.5rem; }
@media (min-width: 768px) { .feature-list { grid-template-columns: 1fr 1fr; gap: 2rem; } }
.feature-item {
  padding: 1.5rem; border-left: 3px solid var(--primary);
  background: var(--bg-card); border-radius: 0 var(--radius) var(--radius) 0;
  box-shadow: 0 2px 8px rgba(29, 33, 41, 0.04);
}
.feature-item h3 { margin: 0 0 0.5rem; font-size: 1.05rem; }
.feature-item p { margin: 0; color: var(--muted); font-size: 0.92rem; }

.table-wrap { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--border); box-shadow: var(--shadow); }
.compare-table {
  width: 100%; border-collapse: collapse; background: var(--bg-card);
}
.compare-table th, .compare-table td {
  padding: 1rem 1.25rem; text-align: left; border-bottom: 1px solid var(--border);
}
.compare-table th { background: var(--bg-muted); font-size: 0.8rem; color: var(--muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.05em; }
.compare-table td:first-child { font-weight: 600; color: var(--text); }
.compare-table tr:last-child td { border-bottom: none; }
.compare-table td:nth-child(2) { color: var(--primary); font-weight: 500; }

/* FAQ */
.faq-section { padding-bottom: 6rem; }
.faq-grid {
  display: grid; gap: 1rem; max-width: 800px; margin: 0 auto;
}
.faq-item {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden;
  transition: border-color 0.25s, box-shadow 0.25s;
  box-shadow: 0 2px 8px rgba(29, 33, 41, 0.04);
}
.faq-item[open] { border-color: var(--border-hover); box-shadow: var(--shadow); }
.faq-item summary {
  cursor: pointer; font-weight: 600; padding: 1.25rem 1.5rem;
  list-style: none; display: flex; justify-content: space-between; align-items: center;
  font-size: 1rem; color: var(--text);
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; font-size: 1.25rem; color: var(--primary); font-weight: 400;
}
.faq-item[open] summary::after { content: "−"; }
.faq-body {
  padding: 0 1.5rem 1.25rem; color: var(--muted); font-size: 0.95rem;
  border-top: 1px solid var(--border);
}
.faq-body p { margin: 1rem 0 0; }
.faq-body ul { margin: 0.75rem 0 0; padding-left: 1.2rem; }
.faq-body li { margin-bottom: 0.35rem; }
.faq-body strong { color: var(--text); }

.cta-bottom {
  text-align: center; padding: 5rem 1.5rem;
  background: linear-gradient(180deg, var(--bg) 0%, var(--primary-soft) 100%);
  border-top: 1px solid var(--border);
}
.cta-bottom h2 { margin: 0 0 0.75rem; font-size: clamp(1.5rem, 4vw, 2rem); }
.cta-bottom p { color: var(--muted); margin: 0 0 2rem; max-width: 28em; margin-left: auto; margin-right: auto; }

/* Inner pages */
.page-main {
  max-width: 720px; margin: 0 auto; padding: 4rem 1.5rem 5rem;
}
.page-main h1 { font-size: 2.25rem; margin-bottom: 0.75rem; color: var(--text); }
.page-main .lead { font-size: 1.1rem; color: var(--muted); margin-bottom: 2rem; }
.page-main h2 { margin-top: 2.5rem; font-size: 1.25rem; color: var(--text); }
.page-main p, .page-main li { color: var(--muted); }

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 3rem 1.5rem 2rem;
  background: var(--bg-elevated);
}
.footer-inner {
  max-width: var(--max); margin: 0 auto 2rem;
  display: grid; gap: 2rem;
}
@media (min-width: 768px) {
  .footer-inner { grid-template-columns: 1.5fr 1fr 1fr 1fr; }
}
.footer-brand strong {
  font-size: 1.1rem; color: var(--text);
}
.footer-brand p { color: var(--muted); font-size: 0.9rem; margin: 0.5rem 0 0; max-width: 18em; }
.footer-col h4 {
  font-size: 0.75rem; font-weight: 600; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--muted); margin: 0 0 1rem;
}
.footer-col a {
  display: block; color: var(--muted); text-decoration: none;
  font-size: 0.9rem; margin-bottom: 0.5rem; transition: color 0.2s;
}
.footer-col a:hover { color: var(--primary); }
.copy {
  text-align: center; color: var(--muted); font-size: 0.82rem; margin: 0;
  padding-top: 2rem; border-top: 1px solid var(--border);
  max-width: var(--max); margin-left: auto; margin-right: auto;
}
.copy a { color: var(--primary); }