/* =============================================================================
   MGB64 browser demo — landing page.
   Aesthetic: "phosphor dossier" — a cinematic near-black surface, a spy-thriller
   reticle/gun-barrel motif, and a single muted-phosphor accent. Deliberately
   dark-committed (it fronts a dark game); every surface is intentional, not a
   default. Self-contained: system fonts only, no network assets.
   ========================================================================== */

:root {
  color-scheme: dark;
  --bg:         #050607;
  --bg-raised:  #0d0f13;
  --bg-input:   #14171d;
  --border:     #23272f;
  --border-soft:#181b21;
  --text:       #eef1f4;
  --text-dim:   #99a0a9;
  --text-faint: #666c75;
  --accent:     #5ce09a;         /* muted phosphor green */
  --accent-hi:  #8affc0;
  --accent-dim: #2f6b4d;
  --accent-ink: #04140c;
  --amber:      #e8b563;         /* dossier secondary (declassified stamp) */
  --glow:       rgba(92, 224, 154, 0.55);
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* --------------------------------------------------------- cinematic backdrop */

.bg-fx {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
  background: radial-gradient(130% 100% at 50% -20%, #0e141a 0%, var(--bg) 58%);
}
/* faint reticle graph-paper grid, fading out toward the edges */
.bg-grid {
  position: absolute;
  inset: -2px;
  background-image:
    linear-gradient(to right, rgba(120, 200, 160, 0.05) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(120, 200, 160, 0.05) 1px, transparent 1px);
  background-size: 46px 46px;
  mask-image: radial-gradient(120% 90% at 50% 22%, #000 30%, transparent 78%);
  -webkit-mask-image: radial-gradient(120% 90% at 50% 22%, #000 30%, transparent 78%);
}
/* slowly rotating gun-barrel spiral bloom behind the hero */
.bg-barrel {
  position: absolute;
  top: -34vmax;
  left: 50%;
  width: 78vmax;
  height: 78vmax;
  translate: -50% 0;
  border-radius: 50%;
  opacity: 0.5;
  background:
    repeating-conic-gradient(from 0deg,
      rgba(92, 224, 154, 0.00) 0deg,
      rgba(92, 224, 154, 0.055) 7deg,
      rgba(92, 224, 154, 0.00) 15deg);
  mask-image: radial-gradient(closest-side, transparent 34%, #000 41%, transparent 72%);
  -webkit-mask-image: radial-gradient(closest-side, transparent 34%, #000 41%, transparent 72%);
  animation: barrel-spin 90s linear infinite;
}
/* subtle CRT scanlines */
.bg-scan {
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(
    to bottom, rgba(0,0,0,0) 0 2px, rgba(0,0,0,0.16) 2px 3px);
  opacity: 0.35;
  mix-blend-mode: multiply;
}
@keyframes barrel-spin { to { rotate: 360deg; } }

/* ----------------------------------------------------------------- layout */

#gate { position: relative; z-index: 1; }

.wrap {
  max-width: 47rem;
  margin: 0 auto;
  padding: clamp(3rem, 9vh, 6.5rem) clamp(1.1rem, 4vw, 1.75rem) 4rem;
}

/* ------------------------------------------------------------------- hero */

.hero { margin-bottom: 2.5rem; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  margin: 0 0 1.15rem;
  padding: 0.35rem 0.7rem 0.35rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: 2rem;
  background: rgba(13, 15, 19, 0.6);
  backdrop-filter: blur(4px);
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-dim);
}
.sig-dot {
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 0 var(--glow);
  animation: sig-pulse 2.4s var(--ease) infinite;
}
@keyframes sig-pulse {
  0%   { box-shadow: 0 0 0 0 var(--glow); opacity: 1; }
  70%  { box-shadow: 0 0 0 7px rgba(92,224,154,0); opacity: 0.75; }
  100% { box-shadow: 0 0 0 0 rgba(92,224,154,0); opacity: 1; }
}

.wordmark {
  position: relative;
  margin: 0;
  font-size: clamp(3.4rem, 15vw, 6.5rem);
  font-weight: 800;
  letter-spacing: 0.015em;
  line-height: 0.92;
  background: linear-gradient(178deg, #ffffff 0%, #aeb6bf 74%, #7d858f 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  filter: drop-shadow(0 2px 24px rgba(120, 150, 170, 0.14));
}
/* phosphor echo of the wordmark, offset behind — a faint CRT ghost */
.wordmark::after {
  content: attr(data-text);
  position: absolute;
  inset: 0;
  z-index: -1;
  background: none;
  -webkit-text-fill-color: transparent;
  color: transparent;
  text-shadow: 0 0 26px rgba(92, 224, 154, 0.22);
}

.tagline {
  margin: 1.2rem 0 0;
  max-width: 33rem;
  color: var(--text-dim);
  font-size: clamp(1rem, 2.4vw, 1.08rem);
}
.tagline strong { color: var(--text); font-weight: 600; }

.status-line {
  margin: 0;
  min-height: 1.4rem;
  color: var(--text-dim);
  font-family: var(--mono);
  font-size: 0.9rem;
}
.status-line:empty { min-height: 0; }

code, kbd { font-family: var(--mono); font-size: 0.85em; }
code {
  background: var(--bg-input);
  padding: 0.1rem 0.4rem;
  border-radius: 0.3rem;
  color: var(--text);
}
kbd {
  display: inline-block;
  min-width: 1.1em;
  padding: 0.12em 0.42em;
  margin: 0 0.05em;
  text-align: center;
  background: #1b1f26;
  border: 1px solid #2b303a;
  border-bottom-width: 2px;
  border-radius: 0.35rem;
  color: var(--text);
  font-size: 0.78em;
  line-height: 1.35;
}

/* ---------------------------------------------------- picker (primary card) */

.picker {
  position: relative;
  margin-top: 1.75rem;
  padding: clamp(1.35rem, 4vw, 2rem);
  background:
    linear-gradient(180deg, rgba(20,23,29,0.85), rgba(8,10,13,0.9));
  border: 1px solid var(--border);
  border-radius: 1rem;
  box-shadow:
    0 1px 0 rgba(255,255,255,0.04) inset,
    0 30px 70px -40px #000;
  backdrop-filter: blur(6px);
}
/* reticle corner-brackets — the distinctive framing */
.picker::before,
.picker::after {
  content: "";
  position: absolute;
  width: 15px; height: 15px;
  border: 1.5px solid var(--accent-dim);
  opacity: 0.8;
}
.picker::before { top: 9px; left: 9px; border-right: 0; border-bottom: 0; border-top-left-radius: 4px; }
.picker::after  { bottom: 9px; right: 9px; border-left: 0; border-top: 0; border-bottom-right-radius: 4px; }

.picker h2 {
  margin: 0 0 0.5rem;
  font-size: 1.18rem;
  letter-spacing: 0.01em;
}
.picker-sub {
  margin: 0 0 1.4rem;
  color: var(--text-dim);
  font-size: 0.95rem;
}
.picker-sub strong { color: var(--text); }

.file-field { display: block; margin-bottom: 0.5rem; }
.file-label {
  display: block;
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 0.45rem;
}

#rom-input {
  font: inherit;
  font-size: 0.9rem;
  color: var(--text-dim);
  max-width: 100%;
}
#rom-input::file-selector-button {
  font: inherit;
  margin-right: 0.75rem;
  padding: 0.5rem 0.95rem;
  background: var(--bg-input);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 0.5rem;
  cursor: pointer;
  transition: border-color 140ms var(--ease), background-color 140ms var(--ease);
}
#rom-input::file-selector-button:hover {
  border-color: var(--accent-dim);
  background: #1a1e25;
}

#rom-status {
  min-height: 1.3rem;
  margin: 0.85rem 0 0;
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.85rem;
}
#rom-status:empty { min-height: 0; margin: 0; }

.option-row {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  margin: 0.9rem 0 0;
  color: var(--text-dim);
  font-size: 0.9rem;
  cursor: pointer;
  user-select: none;
}
.option-row input[type="checkbox"] {
  margin-top: 0.22rem;
  width: 0.95rem;
  height: 0.95rem;
  accent-color: var(--accent);
  cursor: pointer;
}
.option-row strong { color: var(--text); }
.option-row:hover { color: var(--text); }

/* WEB-018: mouse-sensitivity slider row — label + live value stacked over the
   range input. Overrides the base .option-row's row layout / pointer cursor. */
.option-slider {
  flex-direction: column;
  align-items: stretch;
  gap: 0.4rem;
  cursor: default;
}
.option-label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.6rem;
  cursor: pointer;
}
.range-val {
  color: var(--accent);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}
.option-slider input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
  cursor: pointer;
}
.option-slider input[type="range"]:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  margin-top: 1.2rem;
}

.btn {
  position: relative;
  font: inherit;
  font-weight: 600;
  padding: 0.72rem 1.5rem;
  border-radius: 0.6rem;
  border: 1px solid transparent;
  cursor: pointer;
  overflow: hidden;
  transition: transform 120ms var(--ease), background-color 140ms var(--ease),
              border-color 140ms var(--ease), box-shadow 140ms var(--ease),
              opacity 140ms var(--ease);
}
.btn:active:not(:disabled) { transform: translateY(1px); }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.btn-primary {
  background: linear-gradient(180deg, var(--accent-hi), var(--accent));
  color: var(--accent-ink);
  font-size: 1.05rem;
  letter-spacing: 0.02em;
  box-shadow: 0 8px 26px -12px var(--glow);
}
.btn-primary:hover:not(:disabled) {
  box-shadow: 0 10px 30px -10px var(--glow);
  transform: translateY(-1px);
}
/* scan-sheen sweep on hover */
.btn-primary::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(115deg, transparent 30%, rgba(255,255,255,0.45) 50%, transparent 70%);
  transform: translateX(-120%);
  transition: transform 620ms var(--ease);
}
.btn-primary:hover:not(:disabled)::after { transform: translateX(120%); }
.btn-primary:disabled {
  background: #17231c;
  color: #55665c;
  cursor: default;
  box-shadow: none;
}

.btn-ghost {
  background: transparent;
  color: var(--text-dim);
  border-color: var(--border);
}
.btn-ghost:hover { color: var(--text); border-color: var(--text-faint); }

.overlay-note {
  margin: 1.4rem 0 0;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border-soft);
  color: var(--text-faint);
  font-size: 0.85rem;
}

/* -------------------------------------------------- below the fold (details) */

.fold { margin-top: 2rem; }

.disclosure {
  border: 1px solid var(--border-soft);
  border-radius: 0.75rem;
  background: rgba(11, 13, 17, 0.7);
  margin-bottom: 0.75rem;
  overflow: hidden;
  transition: border-color 140ms var(--ease);
}
.disclosure[open] { border-color: var(--border); }
.disclosure > summary {
  list-style: none;
  cursor: pointer;
  padding: 0.98rem 1.3rem;
  font-weight: 600;
  font-size: 0.98rem;
  color: var(--text);
  position: relative;
  transition: color 140ms var(--ease);
}
.disclosure > summary::-webkit-details-marker { display: none; }
.disclosure > summary::after {
  content: "+";
  position: absolute;
  right: 1.3rem;
  color: var(--accent);
  font-family: var(--mono);
  transition: transform 180ms var(--ease);
}
.disclosure[open] > summary::after { content: "\2212"; }
.disclosure > summary:hover { color: var(--accent); }
.disclosure > summary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
  border-radius: 0.5rem;
}

.disclosure-body {
  padding: 0.4rem 1.3rem 1.45rem;
  color: var(--text-dim);
  border-top: 1px solid var(--border-soft);
}
.disclosure-body h3 {
  margin: 1.35rem 0 0.5rem;
  font-size: 0.74rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
}

.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(13rem, 1fr));
  gap: 0.5rem 2rem;
}
.controls h3 { margin-top: 1.15rem; }
.controls dl {
  margin: 0;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.32rem 1rem;
  align-items: baseline;
}
.controls dt { color: var(--text-dim); font-size: 0.9rem; }
.controls dd { margin: 0; text-align: right; color: var(--text); font-size: 0.9rem; }
.gp-intro { margin: 0.9rem 0 0.6rem; font-size: 0.88rem; }

.diff { margin: 0.4rem 0 0; padding-left: 1.1rem; }
.diff li { margin-bottom: 0.5rem; font-size: 0.94rem; }
.diff strong { color: var(--text); }
.disclosure-body p { font-size: 0.94rem; }

/* ------------------------------------------------------------- link cards */

.links {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 0.75rem;
  max-width: 47rem;
  margin: 0 auto;
  padding: 0 clamp(1.1rem, 4vw, 1.75rem) 4rem;
}
.link-card {
  display: block;
  padding: 1.15rem 1.3rem;
  border: 1px solid var(--border);
  border-radius: 0.75rem;
  background: rgba(11, 13, 17, 0.7);
  text-decoration: none;
  transition: border-color 140ms var(--ease), background-color 140ms var(--ease),
              transform 140ms var(--ease);
}
.link-card:hover {
  border-color: var(--accent-dim);
  background: rgba(14, 17, 22, 0.9);
  transform: translateY(-2px);
}
.link-title { display: block; color: var(--accent); font-weight: 600; font-size: 0.98rem; }
.link-sub { display: block; margin-top: 0.22rem; color: var(--text-dim); font-size: 0.85rem; }
.link-card:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ------------------------------------------------------------ in-game view */

#canvas {
  display: block;
  /* Positioned + above the fixed .bg-fx backdrop (z-index 0): a plain static
   * canvas would paint UNDER any positioned z-indexed sibling, leaving the
   * user hearing the game behind the page background. */
  position: relative;
  z-index: 2;
  width: 100vw;
  height: 100vh;
  height: 100dvh;
  background: #000;
}
#canvas[hidden] { display: none; }
/* Once the game canvas is live, drop the decorative backdrop entirely — no
 * stray fixed layer, no wasted compositing behind the game. :has() is
 * supported by every WebGPU-capable browser (the page gates on WebGPU). */
body:has(#canvas:not([hidden])) .bg-fx { display: none; }

#overlay-hint {
  position: fixed;
  left: 50%;
  bottom: 1.25rem;
  transform: translateX(-50%);
  z-index: 5;
  padding: 0.5rem 1rem;
  background: rgba(8, 10, 12, 0.72);
  border: 1px solid var(--border);
  border-radius: 2rem;
  color: var(--text-dim);
  font-size: 0.82rem;
  letter-spacing: 0.01em;
  pointer-events: none;
  backdrop-filter: blur(6px);
  /* WEB-064: the hint is dismissed by mgb64-shell.js (armHintDismiss) for
   * everyone. This transition is cosmetic only — auto-disabled under
   * prefers-reduced-motion, where the JS timeout still hides the pill (the old
   * CSS keyframe fade was the *only* removal path and it left reduced-motion
   * users with a permanent pill). */
  opacity: 1;
  transition: opacity 600ms var(--ease);
}
#overlay-hint.hint-hidden { opacity: 0; }
#overlay-hint[hidden] { display: none; }
#overlay-hint kbd { border-bottom-width: 1px; }

/* WEB-029: persistent save-failure banner (revealed by mgb64-shell.js when
 * FS.syncfs can't reach browser storage). Amber dossier-secondary = warning. */
#save-banner {
  position: fixed;
  top: 0.75rem;
  left: 50%;
  transform: translateX(-50%);
  z-index: 6;
  max-width: min(92vw, 34rem);
  padding: 0.5rem 1rem;
  background: rgba(38, 24, 8, 0.92);
  border: 1px solid var(--amber);
  border-radius: 0.5rem;
  color: #ffe6c2;
  font-size: 0.82rem;
  text-align: center;
  backdrop-filter: blur(6px);
}
#save-banner[hidden] { display: none; }

/* ------------------------------------------------------------ preferences */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .btn-primary::after { display: none; }
}

@media (max-width: 34rem) {
  .controls dd { text-align: left; }
  .wordmark { letter-spacing: 0.005em; }
}