/* Global styles */
*,
*::before,
*::after {
  box-sizing: border-box;
}

:root {
  --bg: #050816;
  --bg-alt: rgba(8, 15, 40, 0.92);
  --card-bg: rgba(15, 23, 42, 0.85);
  --accent: #7c3aed;
  --accent-soft: rgba(124, 58, 237, 0.18);
  --accent-2: #06b6d4;
  --text-main: #f9fafb;
  --text-muted: #9ca3af;
  --border-subtle: rgba(148, 163, 184, 0.3);
  --shadow-soft: 0 24px 80px rgba(15, 23, 42, 0.75);
  --radius-xl: 24px;
}

html, body {
  margin: 0;
  padding: 0;
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: radial-gradient(circle at top left, #0f172a 0, #020617 40%, #020617 100%);
  color: var(--text-main);
  min-height: 100%;
}

.page-gradient {
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 0% 0%, rgba(37, 99, 235, 0.25), transparent 55%),
    radial-gradient(circle at 100% 0%, rgba(124, 58, 237, 0.35), transparent 55%),
    radial-gradient(circle at 50% 100%, rgba(14, 116, 144, 0.25), transparent 60%);
  opacity: 0.9;
  z-index: -2;
}

.site-header {
  max-width: 1120px;
  margin: 0 auto;
  padding: 20px 20px 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo-mark {
  width: 36px;
  height: 36px;
  border-radius: 999px;
  background: radial-gradient(circle at 30% 30%, var(--accent), #1d2144);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  font-weight: 700;
  color: #e5e7eb;
  box-shadow: 0 0 26px rgba(124, 58, 237, 0.7);
}

.logo-text {
  display: flex;
  flex-direction: column;
}

.logo-title {
  font-family: 'Space Grotesk', system-ui;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 14px;
}

.logo-subtitle {
  font-size: 11px;
  color: var(--text-muted);
}

.nav {
  position: relative;
}

.nav-toggle {
  display: none;
  background: transparent;
  border: 1px solid var(--border-subtle);
  border-radius: 999px;
  color: var(--text-main);
  padding: 6px 12px;
  font-size: 16px;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 18px;
  padding: 6px 14px;
  margin: 0;
  border-radius: 999px;
  background: linear-gradient(120deg, rgba(15,23,42,0.9), rgba(15,23,65,0.9));
  box-shadow: 0 12px 30px rgba(15, 23, 42, 0.6);
  border: 1px solid rgba(148, 163, 184, 0.4);
}

.nav-links li a {
  text-decoration: none;
  font-size: 13px;
  color: var(--text-muted);
  padding: 6px 10px;
  border-radius: 999px;
  transition: all 0.16s ease-out;
}

.nav-links li a:hover {
  color: var(--text-main);
  background: rgba(148, 163, 184, 0.16);
}

.nav-links li a.active {
  color: #f9fafb;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 0 0 22px rgba(56, 189, 248, 0.55);
}

/* Layouts */

.hero-layout {
  max-width: 1120px;
  margin: 10px auto 30px;
  padding: 10px 20px 40px;
  display: grid;
  grid-template-columns: minmax(0, 1.22fr) minmax(0, 1fr);
  gap: 28px;
  align-items: stretch;
}

.hero-text h1 {
  font-family: 'Space Grotesk', system-ui;
  font-weight: 600;
  font-size: 2.6rem;
  margin: 12px 0 16px;
  line-height: 1.1;
}

.hero-text .accent {
  background: linear-gradient(135deg, #f97316, #e5e7eb, #38bdf8);
  -webkit-background-clip: text;
  color: transparent;
}

.hero-lead {
  color: var(--text-muted);
  max-width: 520px;
  font-size: 0.98rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(15,23,42,0.7);
  border: 1px solid rgba(148, 163, 184, 0.5);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
}

.hero-actions {
  display: flex;
  gap: 12px;
  margin: 18px 0 20px;
}

.btn {
  border-radius: 999px;
  padding: 9px 18px;
  font-size: 0.9rem;
  border: 1px solid transparent;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.16s ease-out;
}

.btn.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #f9fafb;
  box-shadow: 0 18px 40px rgba(15, 23, 42, 0.8);
}

.btn.primary:hover {
  box-shadow: 0 22px 55px rgba(15, 23, 42, 0.95);
  transform: translateY(-1px);
}

.btn.ghost {
  background: transparent;
  border-color: rgba(148, 163, 184, 0.6);
  color: var(--text-main);
}

.btn.ghost:hover {
  background: rgba(15,23,42,0.8);
}

.hero-metadata {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr);
  gap: 14px;
  margin-top: 16px;
}

.meta-label {
  display: block;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 2px;
}

.meta-value {
  font-size: 0.9rem;
}

.hero-panel {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.card.glass {
  background: radial-gradient(circle at top left, rgba(30, 64, 175, 0.6), var(--card-bg));
  border-radius: var(--radius-xl);
  padding: 18px 18px 16px;
  border: 1px solid rgba(148, 163, 184, 0.5);
  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(18px);
}

.card.glass.secondary {
  background: radial-gradient(circle at top left, rgba(6, 182, 212, 0.45), var(--card-bg));
}

.hero-card h2, .hero-card h3 {
  margin-top: 0;
  font-family: 'Space Grotesk', system-ui;
}

.key-list {
  padding-left: 18px;
  margin: 8px 0 10px;
}

.key-list li span {
  font-weight: 600;
}

.equation-caption {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
  margin-top: 10px;
}

.equation {
  font-family: 'Space Grotesk', ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
  font-size: 0.9rem;
  color: #e5e7eb;
  padding: 8px 10px;
  border-radius: 14px;
  background: rgba(15,23,42,0.85);
  border: 1px solid rgba(148, 163, 184, 0.4);
}

.step-list {
  padding-left: 18px;
  margin: 8px 0;
}

.step-list li {
  margin-bottom: 4px;
}

/* Content pages */

.content {
  max-width: 960px;
  margin: 10px auto 40px;
  padding: 10px 20px 40px;
}

.paper {
  background: var(--bg-alt);
  border-radius: var(--radius-xl);
  padding: 22px 22px 26px;
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(22px);
}

.paper h1 {
  font-family: 'Space Grotesk', system-ui;
  margin-top: 0;
  margin-bottom: 18px;
}

.paper h2 {
  margin-top: 18px;
  margin-bottom: 6px;
}

.paper h3 {
  margin-top: 12px;
  margin-bottom: 4px;
}

.paper p {
  font-size: 0.95rem;
  color: var(--text-main);
}

.paper ul {
  padding-left: 18px;
}

.paper li {
  font-size: 0.93rem;
  color: var(--text-main);
}

.paper .equation {
  margin: 8px 0;
}

.strip {
  max-width: 1120px;
  margin: 0 auto 40px;
  padding: 0 20px 10px;
  display: grid;
  gap: 18px;
}

.strip-three {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.strip-item {
  background: rgba(15,23,42,0.9);
  border-radius: 20px;
  border: 1px solid rgba(148, 163, 184, 0.5);
  padding: 14px 16px;
  box-shadow: 0 18px 45px rgba(15, 23, 42, 0.9);
}

.strip-item h3 {
  margin-top: 0;
  font-family: 'Space Grotesk', system-ui;
}

.strip-item p {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Footer */

.site-footer {
  max-width: 1120px;
  margin: 0 auto 30px;
  padding: 10px 20px 0;
  font-size: 0.8rem;
  color: var(--text-muted);
  border-top: 1px solid rgba(148,163,184,0.4);
}

.site-footer p {
  margin: 4px 0;
}

/* Responsive */

@media (max-width: 840px) {
  .hero-layout {
    grid-template-columns: minmax(0, 1fr);
  }
  .hero-panel {
    order: -1;
  }
}

@media (max-width: 720px) {
  .nav-links {
    display: none;
    position: absolute;
    right: 0;
    top: 40px;
    flex-direction: column;
    background: rgba(15,23,42,0.98);
    border-radius: 18px;
    padding: 10px;
    width: 220px;
  }

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

  .nav-links.nav-static {
    display: flex;
    position: static;
    width: auto;
    background: transparent;
    box-shadow: none;
    border: none;
    padding: 0;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .hero-layout {
    padding-top: 0;
  }

  .hero-text h1 {
    font-size: 2.1rem;
  }

  .strip-three {
    grid-template-columns: minmax(0, 1fr);
  }

  .site-header {
    align-items: flex-start;
    gap: 10px;
  }
}