/* ============================================
   Regent Model Website 
   ============================================ */

:root {
  --purple: #6D28D9;
  --purple-light: #8B5CF6;
  --purple-deep: #4C1D95;
  --purple-faint: #F5F3FF;
  --purple-tint: #EDE9FE;
  --purple-border: rgba(109, 40, 217, 0.15);

  --bg: #FFFFFF;
  --bg-alt: #FAFAFA;
  --bg-card: #FFFFFF;
  --bg-code: #F8F6FF;

  --text: #1A1533;
  --text-secondary: #5B5675;
  --text-dim: #8C86A0;

  --green: #059669;
  --green-bg: #ECFDF5;
  --amber: #D97706;
  --amber-bg: #FFFBEB;
  --red: #DC2626;
  --red-bg: #FEF2F2;

  --border: #E8E5F0;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.06), 0 1px 2px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 4px 16px rgba(109, 40, 217, 0.08), 0 2px 6px rgba(0, 0, 0, 0.04);

  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
  --max-w: 1200px;
  --radius: 12px;
}

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

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
}

a { color: var(--purple); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--purple-deep); }

.container { max-width: var(--max-w); margin: 0 auto; padding: 0 2rem; }

/* ---- NAV ---- */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
}

nav .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}

nav .logo-group {
  display: flex; align-items: center; gap: 0.6rem;
}

nav .logo-group img {
  height: 32px; width: auto;
}

nav .logo {
  font-size: 1.05rem; font-weight: 700; color: var(--text);
  letter-spacing: -0.02em;
}

nav .logo span { color: var(--purple); }

nav .links { display: flex; align-items: center; gap: 2rem; }

nav .links a {
  font-size: 0.875rem; color: var(--text-secondary); font-weight: 500;
  transition: color 0.2s;
}

nav .links a:hover { color: var(--purple); }

.nav-cta {
  background: var(--purple); color: #fff !important;
  padding: 0.5rem 1.25rem; border-radius: 8px; font-weight: 600;
  font-size: 0.875rem; transition: background 0.2s;
}

.nav-cta:hover { background: var(--purple-deep); }

/* ---- HERO ---- */
.hero {
  padding: 10rem 0 5rem;
  text-align: center;
  position: relative;
  background: linear-gradient(180deg, var(--purple-faint) 0%, var(--bg) 100%);
}

.hero::before {
  content: '';
  position: absolute; top: 64px; left: 50%; transform: translateX(-50%);
  width: clamp(300px, 80vw, 800px); height: 400px;
  background: radial-gradient(ellipse, rgba(109, 40, 217, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero .hero-logo {
  width: 64px; height: auto; margin-bottom: 1.5rem;
  filter: drop-shadow(0 2px 8px rgba(109, 40, 217, 0.2));
}

.hero h1 {
  font-size: 3.75rem; font-weight: 800; letter-spacing: -0.03em;
  line-height: 1.1; margin-bottom: 1.5rem; position: relative;
  color: var(--text);
}

.hero h1 .accent { color: var(--purple); }

.hero .subtitle {
  font-size: 1.2rem; color: var(--text-secondary); max-width: 680px;
  margin: 0 auto 2.5rem; line-height: 1.7;
}

.hero .tag-row {
  display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap;
}

.tag {
  background: var(--bg);
  border: 1px solid var(--purple-border);
  padding: 0.45rem 1.1rem; border-radius: 100px;
  font-size: 0.82rem; color: var(--purple); font-weight: 500;
  box-shadow: var(--shadow);
}

/* ---- SECTIONS ---- */
section { padding: 5rem 0; }
section:nth-child(even) { background: var(--bg-alt); }

.section-label {
  font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.18em;
  color: var(--purple); font-weight: 700; margin-bottom: 0.5rem;
}

.section-title {
  font-size: 2.25rem; font-weight: 700; letter-spacing: -0.02em;
  margin-bottom: 0.75rem; line-height: 1.2; color: var(--text);
}

.section-desc {
  font-size: 1.05rem; color: var(--text-secondary); max-width: 680px;
  margin-bottom: 3rem; line-height: 1.7;
}

.section-desc.center { margin-left: auto; margin-right: auto; text-align: center; }

/* ---- STATS ---- */
.stats-bar {
  background: var(--purple);
  padding: 2.5rem 0;
}

.stats {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 2rem;
  text-align: center;
}

.stat .number {
  font-size: 2.25rem; font-weight: 800; color: #fff;
  font-family: var(--mono);
}

.stat .label {
  font-size: 0.82rem; color: rgba(255, 255, 255, 0.75); margin-top: 0.25rem;
}

/* ---- CARDS ---- */
.card-grid {
  display: grid; gap: 1.25rem;
  grid-template-columns: repeat(auto-fit, minmax(270px, 1fr));
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.75rem;
  transition: box-shadow 0.3s, transform 0.2s;
  box-shadow: var(--shadow);
  min-width: 0; /* prevent grid blowout from wide content */
}

.card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.card .icon {
  width: 44px; height: 44px; border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.3rem; margin-bottom: 1rem;
  background: var(--purple-faint);
}

.card h3 {
  font-size: 1.05rem; font-weight: 700; margin-bottom: 0.5rem;
  color: var(--text);
}

.card p { font-size: 0.9rem; color: var(--text-secondary); line-height: 1.6; }

/* ---- ARCHITECTURE DIAGRAM ---- */
.arch-section {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 2.5rem;
  box-shadow: var(--shadow);
  overflow: hidden; /* contain the diagram's pre-formatted content */
}

.arch-diagram {
  font-family: var(--mono); font-size: 0.78rem; color: var(--purple);
  background: var(--bg-code); padding: 2rem; border-radius: 8px;
  overflow-x: auto; white-space: pre; line-height: 1.8;
  border: 1px solid var(--purple-border);
  max-width: 100%;
}

/* ---- COMPARISON TABLE ---- */
.table-wrap {
  overflow-x: auto; border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow);
}

.comparison-table {
  width: 100%; border-collapse: collapse;
  font-size: 0.88rem; background: var(--bg-card);
}

.comparison-table th {
  text-align: left; padding: 0.9rem 1.25rem; font-weight: 600;
  color: var(--purple); border-bottom: 2px solid var(--purple-tint);
  font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.08em;
  background: var(--purple-faint);
}

.comparison-table td {
  padding: 0.8rem 1.25rem; border-bottom: 1px solid var(--border);
  color: var(--text-secondary);
}

.comparison-table tr:hover td { background: var(--purple-faint); }

.model-name { color: var(--text); font-weight: 600; }

.check { color: var(--green); font-weight: 700; }
.cross { color: var(--red); opacity: 0.5; }
.partial { color: var(--amber); font-weight: 500; }

/* ---- ZONES ---- */
.zones { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.25rem; }

.zone {
  padding: 1.75rem; border-radius: var(--radius);
  background: var(--bg-card); box-shadow: var(--shadow);
}

.zone h3 { margin-bottom: 0.6rem; font-size: 1rem; font-weight: 700; }
.zone p { font-size: 0.88rem; color: var(--text-secondary); }

.zone.flow { border-left: 4px solid var(--green); }
.zone.flow h3 { color: var(--green); }

.zone.caution { border-left: 4px solid var(--amber); }
.zone.caution h3 { color: var(--amber); }

.zone.halt { border-left: 4px solid var(--red); }
.zone.halt h3 { color: var(--red); }

/* ---- SIZES ---- */
.sizes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.25rem; }

.size-card {
  background: var(--bg-card); border-radius: var(--radius); padding: 2rem;
  border: 1px solid var(--border); box-shadow: var(--shadow);
  text-align: center; min-width: 0;
}

.size-card.featured { border-color: var(--purple); box-shadow: var(--shadow-lg); }

.size-card .size-name {
  font-size: 1.75rem; font-weight: 800; color: var(--purple);
  margin-bottom: 0.15rem;
}

.size-card .size-label {
  font-size: 0.75rem; color: var(--text-dim); text-transform: uppercase;
  letter-spacing: 0.12em; margin-bottom: 1.5rem;
}

.size-card .specs { text-align: left; }

.size-card .spec {
  display: flex; justify-content: space-between;
  padding: 0.4rem 0; border-bottom: 1px solid var(--border);
  font-size: 0.85rem;
}

.size-card .spec .label { color: var(--text-dim); }
.size-card .spec .value { color: var(--text); font-weight: 600; font-family: var(--mono); }

/* ---- NOVELTY ---- */
.novelty-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem;
}

.novelty-item {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.75rem;
  box-shadow: var(--shadow); position: relative;
  min-width: 0;
}

.novelty-num {
  font-family: var(--mono); font-size: 0.85rem; font-weight: 700;
  color: var(--purple); letter-spacing: 0.05em;
  margin-bottom: 0.6rem;
}

.novelty-item h3 {
  font-size: 1.1rem; font-weight: 700; color: var(--text);
  margin-bottom: 0.85rem; line-height: 1.3;
}

.novelty-item p {
  font-size: 0.88rem; color: var(--text-secondary);
  line-height: 1.6; margin-bottom: 0.6rem;
}

.novelty-item p:last-child { margin-bottom: 0; }

.novelty-item strong {
  color: var(--text); font-weight: 600;
}

/* ---- VARIANTS ---- */
.variants { display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; }

.variant {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 2.25rem;
  box-shadow: var(--shadow); position: relative;
  min-width: 0;
}

.variant-closed {
  border: 2px solid var(--purple);
  background: linear-gradient(180deg, var(--purple-faint) 0%, var(--bg-card) 30%);
  box-shadow: var(--shadow-lg);
}

.variant-label {
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.12em; margin-bottom: 0.6rem;
}

.variant-open .variant-label { color: var(--green); }
.variant-closed .variant-label { color: var(--purple); }

.variant-name {
  font-size: 1.75rem; font-weight: 800; color: var(--text);
  letter-spacing: -0.02em; margin-bottom: 0.25rem;
}

.variant-scale {
  font-family: var(--mono); font-size: 0.85rem; color: var(--purple);
  font-weight: 600; margin-bottom: 1rem;
}

.variant-desc {
  font-size: 0.95rem; color: var(--text-secondary); line-height: 1.6;
  margin-bottom: 1.25rem;
}

.variant-list {
  list-style: none; padding: 0; margin-bottom: 1.5rem;
}

.variant-list li {
  font-size: 0.88rem; color: var(--text-secondary); padding: 0.4rem 0;
  border-bottom: 1px solid var(--border); padding-left: 1.25rem;
  position: relative;
}

.variant-list li::before {
  content: '✓'; position: absolute; left: 0; color: var(--purple);
  font-weight: 700;
}

.variant-list li:last-child { border-bottom: none; }

.variant-cta {
  display: inline-block; padding: 0.65rem 1.5rem; border-radius: 8px;
  font-weight: 600; font-size: 0.875rem; transition: all 0.2s;
  border: 1px solid var(--purple); color: var(--purple);
  background: transparent;
}

.variant-cta:hover { background: var(--purple-faint); color: var(--purple-deep); }

.variant-cta-primary {
  background: var(--purple); color: #fff; border-color: var(--purple);
}

.variant-cta-primary:hover { background: var(--purple-deep); color: #fff; }

/* ---- USE CASES ---- */
.use-case-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem;
}

.use-case {
  background: var(--bg-card); border-radius: var(--radius); padding: 1.75rem;
  border: 1px solid var(--border); box-shadow: var(--shadow);
  min-width: 0;
}

.use-case h3 {
  font-size: 1.05rem; font-weight: 700; color: var(--text);
  margin-bottom: 0.35rem;
}

.use-case .fit {
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.1em; margin-bottom: 0.6rem;
  display: inline-block; padding: 0.2rem 0.6rem; border-radius: 4px;
}

.use-case .fit.strong { color: var(--green); background: var(--green-bg); }
.use-case .fit.good { color: var(--purple); background: var(--purple-faint); }
.use-case .fit.emerging { color: var(--amber); background: var(--amber-bg); }

.use-case p { font-size: 0.88rem; color: var(--text-secondary); }

/* ---- CODE BLOCK ---- */
.code-block {
  background: var(--bg-code); border: 1px solid var(--purple-border);
  border-radius: 8px; padding: 1.5rem 2rem; overflow-x: auto;
  font-family: var(--mono); font-size: 0.82rem; line-height: 1.7;
  color: var(--text-secondary);
  max-width: 100%; box-sizing: border-box;
}

.code-block .comment { color: var(--text-dim); }
.code-block .keyword { color: var(--purple); }

/* ---- CALLOUT ---- */
.callout {
  background: var(--purple-faint); border: 1px solid var(--purple-border);
  border-radius: var(--radius); padding: 1.25rem 1.75rem;
  margin-top: 2rem; font-size: 0.9rem; color: var(--purple-deep);
  line-height: 1.6;
}

.callout strong { font-weight: 700; }

/* ---- FOOTER ---- */
footer {
  padding: 3rem 0; border-top: 1px solid var(--border);
  text-align: center; font-size: 0.85rem;
}

footer .footer-logo {
  display: flex; align-items: center; justify-content: center; gap: 0.5rem;
  margin-bottom: 0.75rem;
}

footer .footer-logo img { height: 24px; }

footer .footer-logo span { font-weight: 700; color: var(--text); }

footer p { color: var(--text-dim); }

footer .disclaimer {
  margin-top: 0.5rem; font-size: 0.78rem; color: var(--text-dim);
  max-width: 600px; margin-left: auto; margin-right: auto;
}

/* ---- NAV TOGGLE ---- */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  z-index: 110;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}

nav.nav-open .nav-toggle span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
nav.nav-open .nav-toggle span:nth-child(2) { opacity: 0; transform: scaleX(0); }
nav.nav-open .nav-toggle span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---- RESPONSIVE ---- */
@media (max-width: 900px) {
  .hero h1 { font-size: 2.5rem; }
  .hero .subtitle { font-size: 1rem; }
  .section-title { font-size: 1.8rem; }
  .card-grid { grid-template-columns: 1fr; }
  .zones { grid-template-columns: 1fr; }
  .sizes { grid-template-columns: 1fr; }
  .use-case-grid { grid-template-columns: 1fr; }
  .variants { grid-template-columns: 1fr; }
  .novelty-grid { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .arch-diagram { font-size: 0.6rem; }

  .nav-toggle { display: flex; }

  nav .links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: rgba(255, 255, 255, 0.98);
    border-bottom: 1px solid var(--border);
    padding: 0.5rem 1.5rem 1.5rem;
    gap: 0;
    backdrop-filter: blur(20px);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
    z-index: 99;
  }

  nav.nav-open .links { display: flex; }

  nav .links a {
    padding: 0.85rem 0;
    border-bottom: 1px solid var(--border);
    font-size: 0.95rem;
  }

  nav .links .nav-cta {
    border-bottom: none;
    margin-top: 0.75rem;
    text-align: center;
    display: block;
  }
}

@media (max-width: 600px) {
  .hero h1 { font-size: 1.9rem; }
  .hero { padding: 8rem 0 3rem; }
  .stats { grid-template-columns: 1fr 1fr; gap: 1rem; }
  .container { padding: 0 1rem; }
  .stat .number { font-size: 1.75rem; }
  section { padding: 3rem 0; }
  .section-title { font-size: 1.5rem; }
  .section-desc { margin-bottom: 2rem; }
  .card { padding: 1.25rem; }
  .variant { padding: 1.5rem; }
  .novelty-item { padding: 1.25rem; }
  .size-card { padding: 1.5rem; }
  .arch-section { padding: 1.25rem; }
  .arch-diagram { font-size: 0.5rem; padding: 1rem; }
  .code-block { padding: 1rem 1.25rem; }
  .callout { padding: 1rem 1.25rem; }
  .zones { gap: 0.75rem; }
  .stats-bar { padding: 1.75rem 0; }
  .hero h1 { letter-spacing: -0.02em; }
  .hero .subtitle { font-size: 0.95rem; }
}