:root {
  --bg: #070b17;
  --panel: rgba(14, 20, 40, 0.78);
  --panel-strong: #121a33;
  --line: rgba(255, 255, 255, 0.1);
  --text: #f5f7ff;
  --muted: #a5b0d6;
  --primary: #7c5cff;
  --primary-2: #3fc6ff;
  --accent: #ffd56a;
  --success: #68f3b2;
  --shadow: 0 20px 70px rgba(0, 0, 0, 0.35);
  --radius: 22px;
  --max: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at top, rgba(90, 77, 255, 0.28), transparent 28%),
    radial-gradient(circle at 80% 20%, rgba(63, 198, 255, 0.16), transparent 22%),
    linear-gradient(180deg, #050812 0%, #091022 48%, #060912 100%);
}

a { color: inherit; text-decoration: none; }
button, input, textarea { font: inherit; }

.site-shell {
  min-height: 100vh;
  overflow: hidden;
}

.topbar {
  width: min(var(--max), calc(100% - 32px));
  margin: 18px auto 0;
  padding: 14px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(10, 14, 30, 0.75);
  border: 1px solid var(--line);
  border-radius: 18px;
  backdrop-filter: blur(18px);
  position: sticky;
  top: 14px;
  z-index: 20;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.brand-mark {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  border-radius: 12px;
  color: #0a1120;
  background: linear-gradient(135deg, var(--accent), #fff0af);
}

.nav {
  display: flex;
  align-items: center;
  gap: 18px;
}

.nav a {
  color: var(--muted);
  font-size: 14px;
}

.nav a:hover,
.nav a:focus-visible {
  color: var(--text);
}

.nav-cta {
  padding: 10px 14px;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  color: white !important;
}

.nav-toggle {
  display: none;
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
  color: white;
  border-radius: 12px;
  padding: 8px 12px;
}

.hero,
.section {
  width: min(var(--max), calc(100% - 32px));
  margin: 0 auto;
}

.hero {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr;
  gap: 30px;
  align-items: center;
  padding: 72px 0 44px;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 14px;
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero h1,
.section h2,
.about-page h1 {
  margin: 0 0 16px;
  line-height: 1.05;
  letter-spacing: -0.03em;
}

.hero h1 { font-size: clamp(40px, 7vw, 72px); }
.section h2, .about-page h1 { font-size: clamp(30px, 4vw, 48px); }

.hero-text,
.section-head p,
.feature-card p,
.scenario-card p,
.quote-card p,
.price-card li,
.faq-answer p,
.contact-form span,
.contact-form input,
.contact-form textarea,
.about-page p {
  color: var(--muted);
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin: 28px 0 22px;
}

.btn {
  border: 0;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0 18px;
  border-radius: 14px;
  transition: 0.2s ease;
}

.btn:hover,
.btn:focus-visible {
  transform: translateY(-1px);
  outline: none;
}

.btn-primary {
  color: white;
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  box-shadow: 0 16px 40px rgba(80, 112, 255, 0.28);
}

.btn-secondary {
  color: white;
  background: rgba(255,255,255,0.06);
  border: 1px solid var(--line);
}

.hero-points {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
  display: grid;
  gap: 8px;
}

.cosmos-card,
.feature-card,
.scenario-card,
.price-card,
.quote-card,
.payment-card,
.answer-panel,
.prompt-panel,
.roadmap-item {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.cosmos-card {
  padding: 22px;
  min-height: 420px;
  position: relative;
}

.cosmos-stage { display: none; }
.cosmos-stage.active { display: block; }

.stage-tag,
.plan-tag,
.answer-role {
  display: inline-block;
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(255,255,255,0.08);
  color: #d7defd;
  font-size: 12px;
  margin-bottom: 12px;
}

.stage-controls {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin-top: 26px;
}

.stage-btn,
.prompt-btn,
.method-chip,
.faq-question {
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
  color: white;
  border-radius: 14px;
  cursor: pointer;
}

.stage-btn,
.method-chip {
  min-height: 42px;
  padding: 0 12px;
}

.stage-btn.active,
.prompt-btn.active,
.method-chip.active {
  background: linear-gradient(135deg, rgba(124,92,255,0.3), rgba(63,198,255,0.22));
  border-color: rgba(147, 186, 255, 0.42);
}

.section {
  padding: 54px 0;
}

.section-head {
  max-width: 760px;
  margin-bottom: 28px;
}

.demo-grid {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 18px;
}

.prompt-panel,
.answer-panel {
  padding: 18px;
}

.prompt-panel {
  display: grid;
  gap: 12px;
  align-content: start;
}

.prompt-btn {
  min-height: 52px;
  padding: 0 16px;
  text-align: left;
}

.answer-card { display: none; }
.answer-card.active { display: block; }

.card-grid {
  display: grid;
  gap: 18px;
}
.card-grid.four { grid-template-columns: repeat(4, 1fr); }
.card-grid.three { grid-template-columns: repeat(3, 1fr); }
.card-grid.two { grid-template-columns: repeat(2, 1fr); }

.feature-card,
.scenario-card,
.quote-card,
.price-card {
  padding: 22px;
}

.scenario-grid,
.price-grid {
  display: grid;
  gap: 18px;
}
.scenario-grid { grid-template-columns: repeat(3, 1fr); }
.price-grid { grid-template-columns: repeat(3, 1fr); }

.price-card.featured {
  border-color: rgba(255, 213, 106, 0.32);
  transform: translateY(-4px);
}

.price {
  font-size: 36px;
  font-weight: 800;
  margin: 14px 0;
}
.price span {
  color: var(--muted);
  font-size: 16px;
  font-weight: 500;
}

.price-card ul {
  margin: 0 0 18px;
  padding-left: 18px;
  display: grid;
  gap: 10px;
}

.membership-gate {
  margin-top: 24px;
  padding: 24px;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.payment-methods {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 16px 0 18px;
}

.payment-section {
  display: block;
}

.payment-card {
  padding: 22px;
  max-width: 520px;
}

.quote-card strong {
  display: block;
  margin-top: 18px;
  color: #dde4ff;
}

.faq-list {
  display: grid;
  gap: 14px;
}

.faq-item {
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255,255,255,0.03);
  overflow: hidden;
}

.faq-question {
  width: 100%;
  text-align: left;
  padding: 18px 20px;
  font-weight: 600;
  border: 0;
  border-radius: 0;
  background: transparent;
}

.faq-answer {
  display: none;
  padding: 0 20px 18px;
}
.faq-item.open .faq-answer { display: block; }

.contact-form {
  padding: 22px;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: var(--panel);
}

.form-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.contact-form label {
  display: grid;
  gap: 8px;
  margin-bottom: 14px;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
  color: white;
  border-radius: 14px;
  padding: 14px 16px;
}

.form-feedback {
  min-height: 22px;
  color: var(--success);
  margin-top: 12px;
}

.modal.hidden { display: none; }
.modal {
  position: fixed;
  inset: 0;
  z-index: 50;
}
.modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(2, 5, 15, 0.68);
  backdrop-filter: blur(6px);
}
.modal-panel {
  position: relative;
  z-index: 1;
  width: min(540px, calc(100% - 24px));
  margin: 8vh auto 0;
  padding: 24px;
  border-radius: 24px;
  background: #0e1530;
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.modal-close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 38px;
  height: 38px;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(255,255,255,0.04);
  color: white;
  cursor: pointer;
}

.modal-summary {
  display: grid;
  gap: 12px;
  margin: 18px 0 20px;
  padding: 16px;
  border-radius: 18px;
  background: rgba(255,255,255,0.04);
}

.about-page .narrow {
  max-width: 960px;
}
.roadmap {
  display: grid;
  gap: 14px;
}
.roadmap-item {
  padding: 18px 20px;
}

@media (max-width: 1024px) {
  .hero,
  .demo-grid,
  .scenario-grid,
  .price-grid,
  .card-grid.four,
  .card-grid.three {
    grid-template-columns: 1fr;
  }

  .hero {
    padding-top: 36px;
  }

  .form-grid,
  .card-grid.two {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 820px) {
  .nav-toggle { display: inline-flex; }
  .nav {
    display: none;
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    flex-direction: column;
    align-items: stretch;
    min-width: 220px;
    padding: 14px;
    border-radius: 18px;
    background: #0d1430;
    border: 1px solid var(--line);
  }
  .nav.open { display: flex; }
  .nav-static { display: flex; position: static; background: transparent; border: 0; padding: 0; min-width: auto; flex-direction: row; }
  .hero { grid-template-columns: 1fr; }
  .stage-controls { grid-template-columns: repeat(2, 1fr); }
}