/* ============================================================
   Base: reset, cosmic background, shared components
   ============================================================ */

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

html, body { height: 100%; }

body {
  font-family: var(--font-ui);
  font-size: var(--fs-body);
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

a { color: inherit; }

/* ---------- Cosmic background system ----------
   Fixed layers so every page shares the same "observatory" sky. */
.cosmos {
  position: fixed;
  inset: 0;
  z-index: -1;
  overflow: hidden;
  background:
    radial-gradient(120% 90% at 78% 12%, var(--bg-2), transparent 60%),
    radial-gradient(120% 120% at 10% 100%, var(--bg-3), transparent 55%),
    var(--bg);
}

/* Drifting nebulae */
.cosmos::before {
  content: "";
  position: absolute;
  inset: -20%;
  background:
    radial-gradient(closest-side at 72% 30%, var(--quantum-soft), transparent 70%),
    radial-gradient(closest-side at 22% 72%, rgba(120, 90, 200, 0.10), transparent 70%);
  filter: blur(20px);
  animation: drift 46s var(--ease) infinite alternate;
}

/* Star field, drawn with layered radial gradients */
.cosmos__stars {
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(1px 1px at 20% 30%, var(--star), transparent),
    radial-gradient(1px 1px at 65% 15%, var(--star), transparent),
    radial-gradient(1px 1px at 80% 60%, var(--star), transparent),
    radial-gradient(1px 1px at 40% 70%, var(--star), transparent),
    radial-gradient(1.5px 1.5px at 90% 80%, var(--star), transparent),
    radial-gradient(1px 1px at 12% 85%, var(--star), transparent),
    radial-gradient(1px 1px at 55% 45%, var(--star), transparent),
    radial-gradient(1.5px 1.5px at 33% 22%, var(--star), transparent);
  opacity: 0.7;
  animation: twinkle 7s ease-in-out infinite alternate;
}

/* Scientific grid overlay */
.cosmos__grid {
  position: absolute;
  inset: 0;
  background-image:
    repeating-linear-gradient(90deg, var(--grid-line) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(0deg, var(--grid-line) 0 1px, transparent 1px 96px);
  mask-image: radial-gradient(120% 120% at 50% 40%, #000 30%, transparent 85%);
  -webkit-mask-image: radial-gradient(120% 120% at 50% 40%, #000 30%, transparent 85%);
}

@keyframes drift {
  from { transform: translate3d(-2%, -1%, 0) scale(1.02); }
  to   { transform: translate3d(3%, 2%, 0) scale(1.08); }
}
@keyframes twinkle {
  from { opacity: 0.45; }
  to   { opacity: 0.8; }
}

/* ---------- Clinical mono labels ---------- */
.mono {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--muted);
}

.stamp {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--muted);
  border: 1px solid var(--border);
  background: var(--surface);
  padding: 7px 12px;
  border-radius: var(--r-pill);
  backdrop-filter: blur(8px);
}
.stamp__dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--quantum);
  box-shadow: 0 0 10px var(--glow);
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: 14px 32px;
  border-radius: var(--r-hand); /* hand-drawn outline */
  text-decoration: none;
  font-weight: 500;
  letter-spacing: 0.02em;
  border: 1.5px solid var(--border-strong);
  color: var(--text);
  background: var(--surface);
  backdrop-filter: blur(8px);
  cursor: pointer;
  transition: transform var(--dur) var(--ease), box-shadow var(--dur) var(--ease),
              background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.btn:hover, .btn:focus-visible {
  transform: translateY(-1px);
  border-color: var(--quantum);
  box-shadow: 0 0 22px var(--glow);
  outline: none;
}
.btn:active { transform: translateY(0); }

.btn--primary {
  background: linear-gradient(180deg, var(--quantum-soft), transparent), var(--surface);
  border-color: color-mix(in srgb, var(--quantum) 45%, transparent);
}
.btn--ghost {
  padding: 13px 22px;
  background: transparent;
  color: var(--muted);
}
.btn--ghost:hover { color: var(--text); }

/* ---------- Top bar ---------- */
.topbar {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
  padding: var(--sp-4) var(--sp-5);
}
.brand {
  text-decoration: none;
  font-family: var(--font-hand);
  font-size: 24px;
  line-height: 1;
  letter-spacing: 0.01em;
  color: var(--text);
}
.brand b { font-weight: 600; }
.brand .x { color: var(--quantum); font-weight: 700; }

.nav { display: flex; gap: var(--sp-2); flex-wrap: wrap; }
.nav a {
  text-decoration: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted-2);
  padding: 8px 12px;
  border-radius: var(--r-pill);
  border: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease),
              background var(--dur) var(--ease);
}
.nav a:hover { color: var(--text); border-color: var(--border); background: var(--surface); }
.nav a[aria-current="page"] { color: var(--text); border-color: var(--border-strong); background: var(--surface); }

/* ---------- Cards ---------- */
.card {
  position: relative;
  background: var(--surface-strong);
  border: 1px solid var(--border);
  border-radius: var(--r-lg);
  padding: var(--sp-6) var(--sp-5);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow);
}

/* ---------- Theme toggle ---------- */
.theme-toggle {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 20;
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: 9px 14px;
  border-radius: var(--r-pill);
  border: 1px solid var(--border);
  background: var(--surface-strong);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  cursor: pointer;
  backdrop-filter: blur(10px);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease),
              box-shadow var(--dur) var(--ease);
}
.theme-toggle:hover { color: var(--text); border-color: var(--quantum); box-shadow: 0 0 20px var(--glow); }
.theme-toggle__dot {
  width: 9px; height: 9px; border-radius: 50%;
  background: var(--quantum);
  box-shadow: 0 0 10px var(--glow);
}

/* ---------- Focus ---------- */
:focus-visible { outline: 2px solid var(--quantum); outline-offset: 3px; }

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  .cosmos::before, .cosmos__stars { animation: none; }
  * { transition-duration: 0.001s !important; }
}

@media (max-width: 640px) {
  .topbar { padding: var(--sp-3) var(--sp-4); }
}