:root {
  color-scheme: dark;
  font-family: Inter, "Noto Sans JP", "Yu Gothic UI", system-ui, sans-serif;
  color: #ecf7ff;
  background: #060b18;
  --ink: #ecf7ff;
  --muted: #8190aa;
  --panel: rgba(12, 21, 41, 0.86);
  --line: rgba(130, 169, 208, 0.22);
  --cyan: #6ff7ff;
  --violet: #aa85ff;
  --gold: #ffe191;
  --danger: #ff607c;
}

* { box-sizing: border-box; }

html { min-width: 320px; }

body {
  min-height: 100vh;
  margin: 0;
  background:
    radial-gradient(circle at 50% 18%, rgba(65, 83, 153, 0.22), transparent 34rem),
    linear-gradient(180deg, #070d1b 0%, #040712 100%);
}

button, a { -webkit-tap-highlight-color: transparent; }

button {
  font: inherit;
  color: inherit;
}

.page-shell {
  width: min(920px, calc(100% - 40px));
  margin: 0 auto;
  padding: 28px 0 56px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.17em;
  text-decoration: none;
}

.brand-mark {
  width: 14px;
  height: 14px;
  border: 2px solid var(--cyan);
  border-radius: 50%;
  box-shadow: 0 0 16px rgba(111, 247, 255, 0.7);
}

.challenge-number,
.eyebrow,
.overlay-kicker,
.control-hint,
.meters dt,
.result-grid dt {
  color: var(--muted);
  font-size: 0.67rem;
  font-weight: 800;
  letter-spacing: 0.15em;
}

.game-heading {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 32px;
  padding: 34px 2px 24px;
}

.eyebrow { margin: 0 0 8px; }

h1 {
  margin: 0;
  font-size: clamp(2.55rem, 8vw, 5rem);
  font-weight: 850;
  line-height: 0.98;
  letter-spacing: -0.065em;
}

.tagline {
  margin: 12px 0 0;
  color: #9eacc1;
  font-size: clamp(0.86rem, 2.2vw, 1rem);
  letter-spacing: 0.08em;
}

.meters {
  display: grid;
  grid-template-columns: repeat(2, minmax(76px, 1fr));
  gap: 8px;
  width: min(300px, 42%);
  margin: 0;
}

.meters div {
  min-width: 0;
  padding: 9px 11px;
  border: 1px solid var(--line);
  background: rgba(8, 15, 30, 0.72);
}

.meters dt,
.meters dd { margin: 0; }

.meters dd {
  margin-top: 3px;
  color: var(--cyan);
  font: 700 1.05rem/1.1 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.board-shell {
  position: relative;
  width: min(800px, 100%);
  margin: 0 auto;
  overflow: hidden;
  border: 1px solid rgba(130, 169, 208, 0.32);
  border-radius: 4px;
  background: #071022;
  box-shadow: 0 28px 90px rgba(0, 0, 0, 0.38), 0 0 0 1px rgba(111, 247, 255, 0.03);
}

.game-board {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 5 / 6;
  outline: 0;
  touch-action: none;
  user-select: none;
}

.game-board:focus-visible { box-shadow: inset 0 0 0 3px var(--cyan); }

.board-overlay {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 26px;
  background: rgba(2, 7, 18, 0.63);
  backdrop-filter: blur(7px);
  transition: opacity 180ms ease, visibility 180ms ease;
}

.board-overlay.is-hidden {
  visibility: hidden;
  opacity: 0;
  pointer-events: none;
}

.overlay-card {
  width: min(530px, 100%);
  padding: clamp(26px, 6vw, 48px);
  border: 1px solid rgba(111, 247, 255, 0.38);
  background: linear-gradient(145deg, rgba(16, 29, 56, 0.97), rgba(7, 14, 31, 0.97));
  box-shadow: 0 18px 70px rgba(0, 0, 0, 0.5), inset 0 0 42px rgba(72, 104, 189, 0.08);
}

.overlay-kicker {
  margin: 0 0 13px;
  color: var(--cyan);
}

.overlay-card h2 {
  margin: 0;
  font-size: clamp(1.8rem, 6vw, 3.35rem);
  line-height: 1.16;
  letter-spacing: -0.045em;
}

.intro-instructions {
  display: grid;
  gap: 9px;
  margin: 28px 0;
}

.intro-instructions p {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin: 0;
  color: #b5c2d5;
  font-size: 0.9rem;
}

.intro-instructions span {
  color: var(--violet);
  font: 700 0.72rem ui-monospace, SFMono-Regular, Consolas, monospace;
}

.primary-button {
  width: 100%;
  min-height: 54px;
  padding: 13px 22px;
  border: 0;
  border-radius: 2px;
  background: linear-gradient(90deg, #79f7ff, #9d9cff);
  color: #061022;
  font-weight: 850;
  letter-spacing: 0.07em;
  cursor: pointer;
  box-shadow: 0 0 28px rgba(111, 247, 255, 0.16);
}

.primary-button:hover { filter: brightness(1.08); }
.primary-button:focus-visible { outline: 3px solid var(--gold); outline-offset: 3px; }

.small-note {
  margin: 13px 0 0;
  color: var(--muted);
  font-size: 0.75rem;
  text-align: center;
}

.result-message {
  min-height: 1.6em;
  margin: 14px 0 22px;
  color: #aebbd0;
}

.result-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  margin: 0 0 22px;
}

.result-grid div {
  padding: 11px 13px;
  border: 1px solid var(--line);
  background: rgba(3, 9, 22, 0.46);
}

.result-grid dt,
.result-grid dd { margin: 0; }

.result-grid dd {
  margin-top: 3px;
  color: var(--cyan);
  font: 700 1.2rem ui-monospace, SFMono-Regular, Consolas, monospace;
}

.game-controls {
  width: min(800px, 100%);
  margin: 0 auto;
  padding: 18px 2px 0;
}

.status-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
  min-height: 24px;
}

.status-wrap p {
  margin: 0;
  color: #aebbd0;
  font-size: 0.86rem;
}

.status-light {
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 12px var(--cyan);
}

.piece-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 13px;
}

.piece-actions span {
  min-width: 0;
  margin-right: auto;
  color: var(--ink);
  font-size: 0.82rem;
  font-weight: 700;
}

.piece-actions button {
  min-height: 42px;
  padding: 8px 14px;
  border: 1px solid rgba(111, 247, 255, 0.32);
  border-radius: 2px;
  background: rgba(12, 22, 42, 0.85);
  color: #c7faff;
  font-size: 0.78rem;
  font-weight: 750;
  cursor: pointer;
}

.piece-actions button:disabled {
  color: #58647a;
  border-color: rgba(91, 107, 133, 0.2);
  cursor: default;
}

.piece-actions button:not(:disabled):hover { border-color: var(--cyan); }

.control-hint {
  margin: 15px 0 0;
  text-align: right;
}

@media (max-width: 760px) {
  .page-shell { width: min(100% - 22px, 600px); padding-top: 18px; }
  .topbar { padding-bottom: 16px; }
  .challenge-number { font-size: 0.58rem; }
  .game-heading { align-items: flex-start; gap: 18px; padding: 24px 1px 18px; }
  .tagline { letter-spacing: 0.03em; }
  .meters { width: 42%; gap: 5px; }
  .meters div { padding: 7px 8px; }
  .meters dt { font-size: 0.55rem; }
  .meters dd { font-size: 0.82rem; }
  .board-overlay { padding: 17px; }
  .overlay-card { padding: 24px; }
  .intro-instructions { margin: 20px 0; }
  .piece-actions button { min-height: 46px; }
  .control-hint { font-size: 0.58rem; }
}

@media (max-width: 420px) {
  .brand { font-size: 0.62rem; letter-spacing: 0.11em; }
  .challenge-number { max-width: 102px; text-align: right; }
  .game-heading { display: block; }
  .meters { width: 100%; margin-top: 16px; grid-template-columns: repeat(4, 1fr); }
  .meters div { padding: 7px 5px; }
  .meters dt { letter-spacing: 0.08em; }
  .meters dd { font-size: 0.75rem; }
  .overlay-card h2 { font-size: 1.75rem; }
  .intro-instructions p { font-size: 0.77rem; }
  .result-grid { gap: 5px; }
  .result-grid div { padding: 8px 10px; }
  .piece-actions { flex-wrap: wrap; }
  .piece-actions span { flex-basis: 100%; }
  .piece-actions button { flex: 1; }
  .control-hint { text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}