/* Invaders: page frame, the overlay stage, buttons and focus (from Barrage). Sizes are in rem,
   and 1 rem is 1/54 of the world's height (20 px at 1080p): the 1920 x 1080 world is always
   96 x 54 rem, centred, so the overlay lines up with the canvas on a TV, a laptop or a phone. */
:root {
  --ink: #f2f5ff;
  --ink-dim: rgba(232, 238, 255, 0.66);
  --glass: rgba(7, 9, 20, 0.68);
  --glass-hi: rgba(20, 24, 44, 0.88);
  --line: rgba(255, 255, 255, 0.15);
  --gold: #ffd24a;
  --hot: #ff7a2a;
  --cyan: #46f2ff;
  --magenta: #ff4fd8;
  --focus: #ffd24a;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "DejaVu Sans", sans-serif;
  --display: "Bahnschrift", "DejaVu Sans Condensed", "Liberation Sans Narrow", "Arial Narrow", system-ui, sans-serif;
  color-scheme: dark;
}
html { font-size: min(calc(100vh / 54), calc(100vw / 96)); }
html, body { margin: 0; height: 100%; background: #05060b; overflow: hidden; }
body { font-family: var(--font); color: var(--ink); -webkit-font-smoothing: antialiased; user-select: none; }
canvas#game { display: block; width: 100vw; height: 100vh; object-fit: contain; }
body.playing canvas#game { cursor: none; }

#ui { position: fixed; inset: 0; pointer-events: none; }
.screen {
  position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center;
  justify-content: center; gap: 1.6rem; padding: 3rem; box-sizing: border-box;
  pointer-events: auto; opacity: 0; transform: scale(1.03);
  transition: opacity 0.32s ease, transform 0.32s cubic-bezier(0.2, 0.8, 0.2, 1);
}
.screen.show { opacity: 1; transform: none; }
.screen.leaving { pointer-events: none; transform: scale(0.98); }
.screen.dim { background: radial-gradient(ellipse at center, rgba(4, 5, 12, 0.62), rgba(4, 5, 12, 0.9)); }
.screen-title {
  margin: 0; font: 900 4.6rem var(--display); font-stretch: condensed; letter-spacing: 0.08em;
  text-transform: uppercase; text-shadow: 0 0.3rem 1.4rem rgba(0, 0, 0, 0.6);
}
.sub { margin: 0; font-size: 1.6rem; font-weight: 700; color: var(--ink-dim); text-align: center; }
.hint { margin: 0; font-size: 1.15rem; font-weight: 700; color: var(--ink-dim); letter-spacing: 0.06em; }
.row { display: flex; align-items: center; gap: 2rem; }

.menu { display: flex; flex-direction: column; gap: 1rem; min-width: 26rem; }
.menu-row { flex-direction: row; flex-wrap: wrap; justify-content: center; min-width: 0; }

.btn {
  font: 800 1.6rem var(--font); color: var(--ink); padding: 0.9rem 2.2rem; cursor: pointer;
  background: var(--glass); border: 0.12rem solid var(--line); border-radius: 1rem;
  box-shadow: 0 0.4rem 1.4rem rgba(0, 0, 0, 0.35), inset 0 0.08rem 0 rgba(255, 255, 255, 0.08); outline: none;
  transition: transform 0.15s ease, background 0.15s ease, border-color 0.15s ease, box-shadow 0.15s ease;
}
.btn-big { font-size: 2.1rem; padding: 1.1rem 3rem; letter-spacing: 0.04em; }
.btn:focus {
  outline: none; border-color: var(--focus); transform: scale(1.05);
  background: linear-gradient(180deg, rgba(255, 190, 70, 0.34), rgba(255, 110, 30, 0.2)), var(--glass-hi);
  box-shadow: 0 0 0 0.3rem rgba(255, 210, 74, 0.32), 0 0 2.4rem rgba(255, 150, 40, 0.45);
}
.btn:active { transform: scale(0.98); }

.stars i { font-style: normal; color: rgba(255, 255, 255, 0.2); }
.stars i.on { color: var(--gold); text-shadow: 0 0 0.6rem rgba(255, 190, 60, 0.75); }

.toast {
  position: fixed; left: 50%; bottom: 9rem; transform: translate(-50%, 1rem); opacity: 0;
  font: 900 1.6rem var(--font); padding: 0.8rem 1.8rem; border-radius: 1rem;
  background: var(--glass-hi); border: 0.12rem solid var(--line); pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease; z-index: 5;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

@media (prefers-reduced-motion: reduce) {
  .screen, .btn, .toast { transition: none; }
}