/* ═══════════════════════════════════════
   商语通 — 官网样式
   ═══════════════════════════════════════ */

:root {
  --bg: #0b0e17;
  --bg-card: #121624;
  --bg-card-hover: #181d2e;
  --border: #1e2640;
  --text: #e4e8f1;
  --text-dim: #8892a8;
  --primary: #6c5ce7;
  --primary-light: #a29bfe;
  --accent: #00cec9;
  --gradient: linear-gradient(135deg, #6c5ce7, #00cec9);
  --radius: 12px;
  --radius-sm: 8px;
  --max-w: 1100px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Noto Sans SC', -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ════ Navigation ════ */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(11, 14, 23, 0.85);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.nav-logo {
  font-size: 1.2rem;
  font-weight: 700;
  text-decoration: none;
  color: var(--text);
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}
.nav-links a {
  text-decoration: none;
  color: var(--text-dim);
  font-size: 0.9rem;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--text); }
.nav-cta {
  background: var(--gradient);
  color: #fff !important;
  padding: 8px 20px;
  border-radius: 20px;
  font-weight: 500;
}
.nav-cta:hover { opacity: 0.9; color: #fff !important; }
.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text);
  font-size: 1.5rem;
  cursor: pointer;
}

/* ════ Hero ════ */
.hero {
  position: relative;
  padding: 140px 0 100px;
  overflow: hidden;
  text-align: center;
}
.hero-bg {
  position: absolute;
  top: -30%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(108,92,231,0.08), transparent 70%);
  pointer-events: none;
}
.hero-badge {
  display: inline-block;
  background: rgba(108,92,231,0.12);
  border: 1px solid rgba(108,92,231,0.25);
  color: var(--primary-light);
  padding: 6px 18px;
  border-radius: 20px;
  font-size: 0.85rem;
  margin-bottom: 28px;
}
.hero-title {
  font-size: 3.4rem;
  font-weight: 900;
  line-height: 1.2;
  margin-bottom: 20px;
}
.gradient-text {
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero-desc {
  font-size: 1.15rem;
  color: var(--text-dim);
  max-width: 600px;
  margin: 0 auto 36px;
}
.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  margin-bottom: 60px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 30px;
  font-size: 1rem;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.25s;
}
.btn-primary {
  background: var(--gradient);
  color: #fff;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(108,92,231,0.3); }
.btn-secondary {
  background: var(--bg-card);
  color: var(--text);
  border: 1px solid var(--border);
}
.btn-secondary:hover { background: var(--bg-card-hover); }
.hero-preview {
  max-width: 500px;
  margin: 0 auto;
}
.preview-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  text-align: left;
}
.preview-header {
  display: flex;
  gap: 8px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border);
}
.preview-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}
.preview-body {
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.msg {
  max-width: 80%;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  line-height: 1.5;
}
.msg-user {
  background: var(--primary);
  color: #fff;
  align-self: flex-end;
  border-bottom-right-radius: 4px;
}
.msg-ai {
  background: #1a1f32;
  color: var(--text);
  align-self: flex-start;
  border-bottom-left-radius: 4px;
}

/* ════ Section titles ════ */
.section-title {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 12px;
}
.section-desc {
  text-align: center;
  color: var(--text-dim);
  margin-bottom: 48px;
  font-size: 1.05rem;
}

/* ════ Features ════ */
.features { padding: 100px 0; }
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: all 0.25s;
}
.feature-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--primary);
  transform: translateY(-3px);
}
.feature-icon { font-size: 2rem; margin-bottom: 14px; }
.feature-card h3 { font-size: 1.1rem; margin-bottom: 10px; }
.feature-card p { font-size: 0.9rem; color: var(--text-dim); line-height: 1.6; }

/* ════ How it works ════ */
.how {
  padding: 100px 0;
  background: var(--bg-card);
}
.steps {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 0;
}
.step {
  flex: 1;
  max-width: 280px;
  text-align: center;
}
.step-number {
  width: 56px;
  height: 56px;
  background: var(--gradient);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  font-weight: 700;
  margin: 0 auto 16px;
}
.step-content h3 { margin-bottom: 8px; font-size: 1.1rem; }
.step-content p { font-size: 0.9rem; color: var(--text-dim); }
.step-arrow {
  color: var(--primary);
  font-size: 1.6rem;
  padding: 24px 10px 0;
}

/* ════ Cases ════ */
.cases { padding: 100px 0; }
.cases-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.case-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: all 0.25s;
}
.case-card:hover {
  background: var(--bg-card-hover);
  transform: translateY(-3px);
}
.case-icon { font-size: 2rem; margin-bottom: 12px; }
.case-card h3 { font-size: 1rem; margin-bottom: 12px; }
.case-card ul { list-style: none; padding: 0; }
.case-card li {
  font-size: 0.88rem;
  color: var(--text-dim);
  padding: 5px 0;
}
.case-card li::before { content: "✓ "; color: var(--accent); }

/* ════ Compare ════ */
.compare {
  padding: 100px 0;
  background: var(--bg-card);
}
.compare-table {
  max-width: 700px;
  margin: 0 auto;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}
.compare-row {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr;
}
.compare-header {
  background: rgba(108,92,231,0.08);
  font-weight: 500;
}
.compare-col {
  padding: 14px 18px;
  font-size: 0.9rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
}
.compare-row:last-child .compare-col { border-bottom: none; }
.compare-col.highlight { color: var(--accent); }
.compare-label { color: var(--text); font-weight: 500; }

/* ════ Stats ════ */
.stats {
  padding: 80px 0;
  background: var(--gradient);
}
.stats-inner {
  display: flex;
  justify-content: space-around;
  text-align: center;
}
.stat-num { font-size: 2.6rem; font-weight: 900; margin-bottom: 6px; }
.stat-label { font-size: 0.9rem; opacity: 0.85; }

/* ════ Download ════ */
.download { padding: 100px 0; }
.download-box {
  max-width: 560px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 48px 36px;
  text-align: center;
}
.download-info {
  text-align: left;
  margin: 24px 0;
}
.dl-row {
  display: flex;
  justify-content: space-between;
  padding: 10px 0;
  border-bottom: 1px solid var(--border);
}
.dl-row:last-child { border-bottom: none; }
.dl-label { color: var(--text-dim); font-size: 0.9rem; }
.dl-value { font-size: 0.9rem; }
.btn-download {
  padding: 16px 40px;
  font-size: 1.1rem;
  margin: 20px 0;
}
.dl-icon { font-size: 1.3rem; }
.download-note {
  font-size: 0.82rem;
  color: var(--text-dim);
  margin-top: 12px;
}

/* ════ FAQ ════ */
.faq { padding: 100px 0; background: var(--bg-card); }
.faq-list {
  max-width: 680px;
  margin: 0 auto;
}
.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 8px 0;
}
.faq-item summary {
  cursor: pointer;
  padding: 14px 0;
  font-weight: 500;
  font-size: 1rem;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.faq-item summary::after {
  content: "+";
  font-size: 1.3rem;
  color: var(--text-dim);
  transition: transform 0.2s;
}
.faq-item[open] summary::after { content: "−"; }
.faq-item p {
  padding: 0 0 16px;
  color: var(--text-dim);
  font-size: 0.92rem;
  line-height: 1.7;
}
details summary::-webkit-details-marker { display: none; }

/* ════ Footer ════ */
.footer {
  padding: 60px 0 0;
  border-top: 1px solid var(--border);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  gap: 40px;
  padding-bottom: 40px;
}
.footer-logo { font-size: 1.2rem; font-weight: 700; display: block; margin-bottom: 8px; }
.footer-brand p { font-size: 0.88rem; color: var(--text-dim); }
.footer-links {
  display: flex;
  gap: 50px;
}
.footer-col h4 { font-size: 0.88rem; margin-bottom: 14px; color: var(--text-dim); }
.footer-col a {
  display: block;
  font-size: 0.88rem;
  color: var(--text);
  text-decoration: none;
  padding: 4px 0;
  transition: color 0.2s;
}
.footer-col a:hover { color: var(--primary-light); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding: 18px 0;
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-dim);
}

/* ═══════════════════════════════════════
   Responsive
   ═══════════════════════════════════════ */

@media (max-width: 900px) {
  .features-grid { grid-template-columns: repeat(2, 1fr); }
  .cases-grid { grid-template-columns: repeat(2, 1fr); }
  .hero-title { font-size: 2.6rem; }
  .steps { flex-direction: column; align-items: center; gap: 24px; }
  .step-arrow { transform: rotate(90deg); padding: 0; }
  .footer-inner { flex-direction: column; }
  .footer-links { gap: 30px; }
  .stats-inner { gap: 30px; }
}

@media (max-width: 640px) {
  .hero-title { font-size: 2rem; }
  .hero-desc { font-size: 1rem; }
  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--bg);
    padding: 20px;
    border-bottom: 1px solid var(--border);
    gap: 16px;
  }
  .nav-toggle { display: block; }
  .hero-actions { flex-direction: column; align-items: center; }
  .features-grid { grid-template-columns: 1fr; }
  .cases-grid { grid-template-columns: 1fr; }
  .compare-row { grid-template-columns: 1.2fr 1fr 1fr; }
  .compare-col { font-size: 0.8rem; padding: 10px 12px; }
  .stat-num { font-size: 2rem; }
  .section-title { font-size: 1.6rem; }
  .download-box { padding: 32px 20px; }
}