/* ============================================================
   Base / reset / app shell layering
   ============================================================ */

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

html, body {
  height: 100%;
  width: 100%;
  overflow: hidden;
  overscroll-behavior: none;
  background: var(--c-ink);
  color: var(--c-mist);
  font-family: var(--font-text);
  font-size: var(--t-md);
  line-height: var(--lh-body);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  -webkit-tap-highlight-color: transparent;
  -webkit-text-size-adjust: 100%;
  touch-action: manipulation;
}

body {
  position: fixed;
  inset: 0;
  user-select: none;
  -webkit-user-select: none;
}

button, input, textarea, select {
  font: inherit;
  color: inherit;
  border: none;
  background: none;
  outline: none;
}
button { cursor: pointer; -webkit-appearance: none; appearance: none; }
input  { -webkit-appearance: none; appearance: none; }
img, svg, canvas { display: block; max-width: 100%; }
ul, ol { list-style: none; }
a { color: inherit; text-decoration: none; }

:focus-visible {
  outline: 3px solid var(--c-cyan);
  outline-offset: 3px;
  border-radius: 6px;
}

/* ---- Stage: three fixed layers under the UI ---- */
#gl-bg {           /* WebGL / canvas background */
  position: fixed; inset: 0;
  width: 100%; height: 100%;
  z-index: var(--z-bg);
  display: block;
}
#fx {              /* WebGL particle overlay */
  position: fixed; inset: 0;
  width: 100%; height: 100%;
  z-index: var(--z-fx);
  pointer-events: none;
}
#css-fallback {    /* animated gradient if WebGL unavailable */
  position: fixed; inset: 0;
  z-index: var(--z-bg);
  background:
    radial-gradient(120% 90% at 20% 0%, #3a1170 0%, transparent 55%),
    radial-gradient(120% 90% at 90% 20%, #0a4a6b 0%, transparent 50%),
    linear-gradient(160deg, #1a0b3d, #0a0616 70%);
  display: none;
}
body.no-webgl #css-fallback { display: block; animation: hue-drift 24s linear infinite; }

/* ---- App root ---- */
#app {
  position: fixed;
  inset: 0;
  z-index: var(--z-ui);
  display: flex;
  justify-content: center;
  overflow: hidden;
}

.stage {
  position: relative;
  width: 100%;
  max-width: var(--app-max);
  height: 100%;
  padding:
    calc(var(--safe-t) + var(--s-3))
    calc(var(--safe-r) + var(--s-4))
    calc(var(--safe-b) + var(--s-3))
    calc(var(--safe-l) + var(--s-4));
  display: grid;
  grid-template-rows: auto 1fr auto;
  overflow: hidden;
}

/* Screens stack; only .is-active is shown. */
.screen {
  position: absolute;
  inset: 0;
  padding:
    calc(var(--safe-t) + var(--s-4))
    calc(var(--safe-r) + var(--s-4))
    calc(var(--safe-b) + var(--s-4))
    calc(var(--safe-l) + var(--s-4));
  display: flex;
  flex-direction: column;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateY(14px) scale(0.985);
  transition:
    opacity var(--dur-3) var(--e-out),
    transform var(--dur-3) var(--e-out),
    visibility 0s linear var(--dur-3);
}
.screen.is-active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: none;
  transition:
    opacity var(--dur-3) var(--e-out),
    transform var(--dur-4) var(--e-spring-2);
}
.screen.is-leaving {
  opacity: 0;
  transform: translateY(-10px) scale(1.01);
}

/* Scroll region inside screens */
.scroll {
  overflow-y: auto;
  overflow-x: hidden;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  min-height: 0;
}
.scroll::-webkit-scrollbar { width: 0; height: 0; }

/* ---- Utilities ---- */
.center { display: flex; align-items: center; justify-content: center; }
.col    { display: flex; flex-direction: column; }
.row    { display: flex; align-items: center; }
.gap-1 { gap: var(--s-1); } .gap-2 { gap: var(--s-2); }
.gap-3 { gap: var(--s-3); } .gap-4 { gap: var(--s-4); }
.grow  { flex: 1 1 auto; min-height: 0; }
.hidden { display: none !important; }
.mt-a  { margin-top: auto; }
.tc    { text-align: center; }
.wrap-balance { text-wrap: balance; }
.mono  { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }

.grad-text {
  background: linear-gradient(100deg, var(--cat-a), var(--cat-b));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
}
.sr-only {
  position: absolute; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden;
  clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}