:root {
  --bg-1: #0e0f13;
  --bg-2: #141824;
  --glass: rgba(255, 255, 255, 0.06);
  --glass-strong: rgba(255, 255, 255, 0.12);
  --fg: #e8eaed;
  --muted: #aab0b6;
  --accent: #7c5cff;
  --accent-2: #22d3ee;
}

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

html, body {
  height: 100%;
}

body {
  margin: 0;
  color: var(--fg);
  background:
    radial-gradient(1200px 600px at 15% 10%, #1a2240 0%, transparent 60%),
    radial-gradient(1000px 500px at 85% 20%, #162e2d 0%, transparent 60%),
    linear-gradient(180deg, var(--bg-1), var(--bg-2));
  font: 16px/1.4 ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, Apple Color Emoji, Segoe UI Emoji;
  display: grid;
  place-items: center;
  padding: 24px;
}

.app {
  width: min(960px, 92vw);
  display: grid;
  gap: 16px;
}

.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.back-link {
  color: var(--fg);
  text-decoration: none;
  font-size: 0.85rem;
  opacity: 0.9;
}

.back-link:hover {
  opacity: 1;
  text-decoration: underline;
}

.lang-switch {
  display: flex;
  gap: 4px;
}

.lang-switch button {
  border: 1px solid var(--glass-strong);
  background: rgba(255, 255, 255, 0.06);
  color: var(--fg);
  font-size: 0.75rem;
  padding: 4px 10px;
  border-radius: 999px;
  cursor: pointer;
}

.lang-switch button.active {
  background: rgba(124, 92, 255, 0.35);
  border-color: rgba(124, 92, 255, 0.6);
}

.options-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 16px;
  padding: 10px 14px;
  background: linear-gradient(180deg, rgba(255,255,255,0.05), rgba(255,255,255,0.02));
  border: 1px solid var(--glass-strong);
  border-radius: 12px;
}

.option {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--muted);
}

.option select {
  background: rgba(0, 0, 0, 0.35);
  color: var(--fg);
  border: 1px solid var(--glass-strong);
  border-radius: 8px;
  padding: 6px 10px;
}

.option.toggle input {
  accent-color: var(--accent);
}

.series-pill {
  margin-left: auto;
  font-size: 13px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.hud {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.03));
  border: 1px solid var(--glass-strong);
  border-radius: 14px;
  backdrop-filter: blur(10px);
  box-shadow:
    0 10px 30px rgba(0,0,0,0.35),
    inset 0 1px 0 rgba(255,255,255,0.06);
}

.score {
  display: flex;
  align-items: center;
  gap: 10px;
}

.score .label {
  color: var(--muted);
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  font-size: 12px;
}

.score .digits {
  font-variant-numeric: tabular-nums;
  font-size: clamp(28px, 4.5vw, 40px);
  font-weight: 800;
  letter-spacing: 0.02em;
  color: #fff;
  text-shadow:
    0 0 24px rgba(124, 92, 255, 0.25),
    0 0 8px rgba(34, 211, 238, 0.2);
}

.controls {
  display: flex;
  gap: 10px;
  justify-self: center;
}

.btn {
  appearance: none;
  border: 1px solid var(--glass-strong);
  background: linear-gradient(180deg, rgba(255,255,255,0.08), rgba(255,255,255,0.03));
  color: var(--fg);
  padding: 10px 14px;
  border-radius: 999px;
  cursor: pointer;
  font-weight: 600;
  transition: transform .12s ease, box-shadow .2s ease, background .2s ease, border-color .2s ease;
  box-shadow:
    0 6px 16px rgba(0,0,0,0.25),
    inset 0 1px 0 rgba(255,255,255,0.06);
}
.btn.primary {
  background: linear-gradient(135deg, rgba(124, 92, 255, 0.4), rgba(34, 211, 238, 0.35));
  border-color: rgba(124, 92, 255, 0.5);
  color: #fff;
  text-shadow: 0 1px 0 rgba(0,0,0,0.25);
}
.btn:hover {
  transform: translateY(-1px);
  box-shadow:
    0 10px 24px rgba(0,0,0,0.35),
    0 0 24px rgba(124, 92, 255, 0.18);
}
.btn:active {
  transform: translateY(0);
}

.stage {
  position: relative;
  border-radius: 16px;
  padding: 12px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.03));
  border: 1px solid var(--glass-strong);
  backdrop-filter: blur(8px);
  box-shadow:
    0 16px 40px rgba(0,0,0,0.45),
    inset 0 1px 0 rgba(255,255,255,0.06);
}

#pong {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 800 / 500;
  border-radius: 12px;
  background: radial-gradient(120% 90% at 20% 10%, #0d1020 0%, #0b0c12 60%, #0a0a0f 100%);
  border: 1px solid rgba(255,255,255,0.06);
  box-shadow:
    0 0 0 1px rgba(124, 92, 255, 0.2) inset,
    0 30px 60px rgba(0,0,0,0.5),
    0 0 60px rgba(124, 92, 255, 0.08);
}

.tips {
  text-align: center;
  color: var(--muted);
  font-size: 13px;
}

.landscape-hint {
  margin-top: 8px;
  font-size: 12px;
  color: #7dd3fc;
}

@media (max-width: 540px) {
  .hud {
    grid-template-columns: 1fr;
    gap: 10px;
  }
  .controls {
    justify-self: stretch;
  }
  .controls .btn {
    flex: 1;
  }
}