/* =============================================================
   PHYSICAL AI — dedicated dark, futuristic, industrial identity
   Self-contained "world". Everything is scoped under .pa-world so
   nothing here leaks into (or inherits from) the rest of the site.
   Palette blends seamlessly with assets/physical_ai.png:
   near-black navy backgrounds + electric-blue / cyan glow.
   ============================================================= */

.pa-world {
  --pa-bg: #03050c;
  --pa-bg-2: #060b18;
  --pa-panel: rgba(15, 23, 42, 0.55);
  --pa-panel-border: rgba(96, 165, 250, 0.18);
  --pa-panel-border-hover: rgba(96, 165, 250, 0.55);
  --pa-text: #dbe4f4;
  --pa-text-dim: #93a4c4;
  --pa-text-faint: #64748b;
  --pa-blue: #3b82f6;
  --pa-blue-light: #60a5fa;
  --pa-cyan: #22d3ee;
  --pa-heading: #f4f8ff;

  margin: 0;
  min-height: 100vh;
  color: var(--pa-text);
  background-color: var(--pa-bg);
  /* Layered depth: deep radial blue glows over near-black navy, so the
     hero image reads as part of the page rather than pasted on top. */
  background-image:
    radial-gradient(1200px 620px at 50% -8%, rgba(37, 99, 235, 0.22), transparent 60%),
    radial-gradient(900px 700px at 100% 20%, rgba(34, 211, 238, 0.08), transparent 55%),
    radial-gradient(900px 700px at 0% 30%, rgba(59, 130, 246, 0.1), transparent 55%),
    linear-gradient(180deg, var(--pa-bg) 0%, var(--pa-bg-2) 40%, var(--pa-bg) 100%);
  background-attachment: fixed;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  line-height: 1.6;
  position: relative;
  overflow-x: hidden;
}

/* Faint engineering "blueprint" grid — Physics + Data + Systems texture. */
.pa-world::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    linear-gradient(rgba(96, 165, 250, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(96, 165, 250, 0.04) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(120% 100% at 50% 0%, #000 40%, transparent 100%);
  -webkit-mask-image: radial-gradient(120% 100% at 50% 0%, #000 40%, transparent 100%);
}

.pa-world *,
.pa-world *::before,
.pa-world *::after {
  box-sizing: border-box;
}

/* ===================== NAV ===================== */

.pa-nav {
  position: sticky;
  top: 0;
  z-index: 500;
  background: rgba(3, 5, 12, 0.72);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(96, 165, 250, 0.14);
}

.pa-nav-inner {
  width: min(1180px, 100%);
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.pa-nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 1.02rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--pa-heading);
  text-decoration: none;
  white-space: nowrap;
  flex-shrink: 0;
  margin-right: 16px;
}

.pa-nav-mark {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, var(--pa-cyan), var(--pa-blue));
  box-shadow: 0 0 12px rgba(59, 130, 246, 0.9);
}

.pa-nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

.pa-nav-link {
  padding: 7px 13px;
  border-radius: 8px;
  color: var(--pa-text-dim);
  text-decoration: none;
  font-size: 0.92rem;
  white-space: nowrap;
  transition: background-color 0.15s ease, color 0.15s ease;
}

.pa-nav-link:hover {
  background: rgba(96, 165, 250, 0.12);
  color: #fff;
}

.pa-nav-link--current {
  color: #fff;
  background: linear-gradient(90deg, rgba(30, 58, 138, 0.85), rgba(59, 130, 246, 0.65));
}

.pa-nav-hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 38px;
  height: 38px;
  padding: 7px;
  border: 1px solid rgba(96, 165, 250, 0.35);
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
  margin-left: auto;
  flex-shrink: 0;
}

.pa-nav-hamburger span {
  display: block;
  height: 2px;
  background: var(--pa-blue-light);
  border-radius: 2px;
}

/* ===================== SHELL ===================== */

.pa-shell {
  position: relative;
  z-index: 1;
  width: min(1180px, 100%);
  margin: 0 auto;
  padding: 0 24px 80px;
}

/* ===================== HERO ===================== */

.pa-hero {
  text-align: center;
  padding: 72px 0 24px;
}

.pa-hero-eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  letter-spacing: 0.34em;
  text-transform: uppercase;
  color: var(--pa-blue-light);
  margin: 0 0 20px;
  padding: 6px 16px;
  border: 1px solid rgba(96, 165, 250, 0.3);
  border-radius: 999px;
  background: rgba(59, 130, 246, 0.08);
}

.pa-hero-title {
  margin: 0 auto 16px;
  max-width: 15ch;
  font-size: clamp(2rem, 6vw, 4.1rem);
  line-height: 1.05;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--pa-heading);
  text-shadow: 0 0 40px rgba(59, 130, 246, 0.35);
}

.pa-hero-title .pa-accent {
  background: linear-gradient(90deg, var(--pa-blue-light), var(--pa-cyan));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.pa-hero-sub {
  margin: 0 auto 44px;
  max-width: 60ch;
  font-size: clamp(1rem, 2.2vw, 1.22rem);
  color: var(--pa-text-dim);
}

/* Full-bleed hero image that MERGES into the dark background.
   The source PNG already has a near-black backdrop; the edge mask +
   ambient glow dissolve its borders so nothing looks "pasted on". */
.pa-hero-figure {
  margin: 0;
  position: relative;
}

.pa-hero-figure::after {
  /* ambient bloom behind the image */
  content: "";
  position: absolute;
  inset: 6% 2% -8%;
  z-index: -1;
  background: radial-gradient(60% 60% at 50% 45%, rgba(37, 99, 235, 0.35), transparent 72%);
  filter: blur(48px);
}

.pa-hero-image {
  display: block;
  width: 100%;
  height: auto;
  border: 0;
  /* fade all four edges into the page background */
  -webkit-mask-image:
    linear-gradient(to right, transparent 0, #000 6%, #000 94%, transparent 100%),
    linear-gradient(to bottom, transparent 0, #000 5%, #000 92%, transparent 100%);
  -webkit-mask-composite: source-in;
  mask-image:
    linear-gradient(to right, transparent 0, #000 6%, #000 94%, transparent 100%),
    linear-gradient(to bottom, transparent 0, #000 5%, #000 92%, transparent 100%);
  mask-composite: intersect;
}

.pa-hero-caption {
  margin: 20px auto 0;
  max-width: 70ch;
  font-size: 0.9rem;
  color: var(--pa-text-faint);
  text-align: center;
}

/* Divider / marquee line under hero */
.pa-rule {
  height: 1px;
  margin: 56px 0;
  border: 0;
  background: linear-gradient(90deg, transparent, rgba(96, 165, 250, 0.5), transparent);
}

/* ===================== SECTIONS ===================== */

.pa-section {
  margin: 64px 0 0;
}

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

.pa-section-kicker {
  display: block;
  font-size: 0.74rem;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--pa-blue-light);
  margin-bottom: 10px;
}

.pa-section-title {
  margin: 0 0 12px;
  font-size: clamp(1.5rem, 3.4vw, 2.1rem);
  font-weight: 750;
  color: var(--pa-heading);
  letter-spacing: -0.01em;
}

.pa-section-desc {
  margin: 0;
  font-size: 1.02rem;
  color: var(--pa-text-dim);
}

/* ---- Domain grid (the 7 areas shown in the hero image) ---- */

.pa-domain-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
  margin-top: 8px;
}

.pa-domain-card {
  position: relative;
  display: block;
  padding: 22px 22px 20px;
  border-radius: 16px;
  background: var(--pa-panel);
  border: 1px solid var(--pa-panel-border);
  text-decoration: none;
  color: inherit;
  overflow: hidden;
  transition: transform 0.18s ease, border-color 0.18s ease,
    box-shadow 0.18s ease, background-color 0.18s ease;
}

.pa-domain-card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(120% 140% at 0% 0%, rgba(59, 130, 246, 0.14), transparent 55%);
  opacity: 0;
  transition: opacity 0.18s ease;
}

.pa-domain-card:hover {
  transform: translateY(-4px);
  border-color: var(--pa-panel-border-hover);
  background: rgba(20, 32, 58, 0.7);
  box-shadow: 0 18px 40px -20px rgba(37, 99, 235, 0.7);
}

.pa-domain-card:hover::before {
  opacity: 1;
}

.pa-domain-icon {
  font-size: 1.5rem;
  line-height: 1;
  margin-bottom: 12px;
}

.pa-domain-title {
  position: relative;
  margin: 0 0 8px;
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--pa-heading);
}

.pa-domain-desc {
  position: relative;
  margin: 0 0 14px;
  font-size: 0.92rem;
  color: var(--pa-text-dim);
}

.pa-domain-status {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 0.74rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--pa-text-faint);
}

.pa-domain-status::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--pa-cyan);
  box-shadow: 0 0 8px rgba(34, 211, 238, 0.9);
}

/* ---- Content-stream sections (papers / projects / notes) ---- */

.pa-stream-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.pa-stream-card {
  padding: 24px;
  border-radius: 16px;
  background: var(--pa-panel);
  border: 1px solid var(--pa-panel-border);
}

.pa-stream-card h3 {
  margin: 0 0 8px;
  font-size: 1.12rem;
  color: var(--pa-heading);
}

.pa-stream-card p {
  margin: 0;
  font-size: 0.94rem;
  color: var(--pa-text-dim);
}

/* ---- Empty / future-ready placeholder ---- */

.pa-empty {
  margin-top: 8px;
  padding: 40px 28px;
  border-radius: 16px;
  border: 1px dashed rgba(96, 165, 250, 0.28);
  background: rgba(10, 16, 30, 0.4);
  text-align: center;
}

.pa-empty-badge {
  display: inline-block;
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--pa-blue-light);
  padding: 5px 14px;
  border: 1px solid rgba(96, 165, 250, 0.3);
  border-radius: 999px;
  margin-bottom: 14px;
}

.pa-empty p {
  margin: 6px auto 0;
  max-width: 52ch;
  color: var(--pa-text-dim);
  font-size: 0.96rem;
}

/* ===================== FOOTER ===================== */

.pa-footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 48px 24px 56px;
  border-top: 1px solid rgba(96, 165, 250, 0.12);
}

.pa-footer-tagline {
  margin: 0 0 8px;
  font-size: 0.82rem;
  letter-spacing: 0.28em;
  text-transform: uppercase;
  color: var(--pa-blue-light);
}

.pa-footer-note {
  margin: 0;
  font-size: 0.84rem;
  color: var(--pa-text-faint);
}

/* ===================== RESPONSIVE ===================== */

@media (max-width: 760px) {
  .pa-nav-hamburger {
    display: flex;
  }

  .pa-nav-links {
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: 10px 16px 16px;
    background: rgba(3, 5, 12, 0.97);
    border-bottom: 1px solid rgba(96, 165, 250, 0.14);
    display: none;
  }

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

  .pa-nav-link {
    padding: 12px 14px;
  }

  .pa-hero {
    padding: 48px 0 12px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .pa-domain-card {
    transition: none;
  }
}