:root {
  color-scheme: dark;
  --ink: #f4f0e8;
  --muted: #b7c0c1;
  --bg: #11181c;
  --panel: #192429;
  --panel-2: #213035;
  --line: #394b4e;
  --source: #ffcf56;
  --power: #54d69b;
  --terminal: #e58f65;
  --shadow: rgba(0, 0, 0, 0.32);
}

* {
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 15% 18%, rgba(84, 214, 155, 0.16), transparent 26rem),
    linear-gradient(135deg, #11181c 0%, #1f2e2e 48%, #2b2730 100%);
}

button,
select {
  font: inherit;
}

.shell {
  width: min(1120px, calc(100vw - 28px));
  min-height: 100vh;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 24px;
  align-items: center;
  padding: 28px 0;
}

.game-panel,
.side-panel {
  border: 1px solid rgba(244, 240, 232, 0.12);
  background: rgba(25, 36, 41, 0.86);
  box-shadow: 0 24px 80px var(--shadow);
  backdrop-filter: blur(18px);
}

.game-panel {
  border-radius: 8px;
  padding: clamp(16px, 3vw, 28px);
}

.side-panel {
  border-radius: 8px;
  padding: 20px;
}

.topbar {
  display: flex;
  justify-content: space-between;
  align-items: start;
  gap: 16px;
  margin-bottom: 18px;
}

.eyebrow,
h1,
h2,
p {
  margin: 0;
}

.eyebrow {
  color: var(--power);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

h1 {
  margin-top: 3px;
  font-size: clamp(2rem, 4.8vw, 4.7rem);
  line-height: 0.92;
  letter-spacing: 0;
}

.status-pill {
  min-width: 98px;
  border: 1px solid rgba(255, 207, 86, 0.35);
  border-radius: 999px;
  padding: 8px 12px;
  color: var(--source);
  background: rgba(255, 207, 86, 0.1);
  text-align: center;
  font-weight: 800;
  white-space: nowrap;
}

.hud {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
  margin-bottom: 16px;
}

.hud div {
  min-width: 0;
  border: 1px solid rgba(244, 240, 232, 0.1);
  border-radius: 8px;
  padding: 11px 12px;
  background: rgba(17, 24, 28, 0.6);
}

.hud span {
  display: block;
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
  text-transform: uppercase;
}

.hud strong {
  display: block;
  margin-top: 2px;
  font-size: clamp(1.1rem, 2.2vw, 1.5rem);
}

.board-wrap {
  position: relative;
}

.board {
  display: grid;
  grid-template-columns: repeat(var(--size), 1fr);
  width: min(68vh, 100%);
  max-width: 700px;
  aspect-ratio: 1;
  margin: 0 auto;
  border: 3px solid rgba(244, 240, 232, 0.14);
  border-radius: 8px;
  overflow: hidden;
  background: #0d1316;
}

.tile {
  position: relative;
  display: grid;
  place-items: center;
  aspect-ratio: 1;
  border: 1px solid rgba(244, 240, 232, 0.08);
  background:
    linear-gradient(135deg, rgba(255, 255, 255, 0.035), transparent),
    var(--panel-2);
  cursor: pointer;
  transition: background 160ms ease, box-shadow 160ms ease;
}

.tile:focus-visible {
  z-index: 2;
  outline: 3px solid var(--source);
  outline-offset: -3px;
}

.tile.powered {
  background:
    radial-gradient(circle at center, rgba(84, 214, 155, 0.2), transparent 54%),
    var(--panel-2);
  box-shadow: inset 0 0 18px rgba(84, 214, 155, 0.18);
}

.tile.hinted {
  animation: hintPulse 900ms ease 2;
}

.stem {
  position: absolute;
  background: var(--line);
  border-radius: 999px;
  transition: background 160ms ease, box-shadow 160ms ease;
}

.powered .stem {
  background: var(--power);
  box-shadow: 0 0 12px rgba(84, 214, 155, 0.68);
}

.stem.n,
.stem.s {
  width: 18%;
  height: 50%;
  left: 41%;
}

.stem.e,
.stem.w {
  width: 50%;
  height: 18%;
  top: 41%;
}

.stem.n {
  top: 0;
}

.stem.s {
  bottom: 0;
}

.stem.e {
  right: 0;
}

.stem.w {
  left: 0;
}

.hub {
  width: 38%;
  aspect-ratio: 1;
  border-radius: 50%;
  background: #4e6062;
  box-shadow: inset 0 -4px 10px rgba(0, 0, 0, 0.22);
  z-index: 1;
}

.powered .hub {
  background: var(--power);
  box-shadow: 0 0 18px rgba(84, 214, 155, 0.74);
}

.source .hub {
  background: var(--source);
  box-shadow: 0 0 20px rgba(255, 207, 86, 0.85);
}

.terminal .hub {
  background: var(--terminal);
}

.terminal.powered .hub {
  background: linear-gradient(135deg, var(--terminal), var(--source));
}

.win-screen {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: rgba(9, 13, 15, 0.72);
  backdrop-filter: blur(8px);
}

.win-screen[hidden] {
  display: none;
}

.win-screen div {
  width: min(320px, 82%);
  border: 1px solid rgba(255, 207, 86, 0.35);
  border-radius: 8px;
  padding: 22px;
  background: rgba(25, 36, 41, 0.94);
  text-align: center;
}

.win-screen p {
  color: var(--power);
  font-weight: 900;
  text-transform: uppercase;
}

.win-screen strong {
  display: block;
  margin-top: 6px;
  font-size: 2rem;
}

.controls {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr;
  gap: 10px;
  margin-top: 16px;
}

button,
select {
  min-height: 44px;
  border: 1px solid rgba(244, 240, 232, 0.14);
  border-radius: 8px;
  color: var(--ink);
  background: rgba(244, 240, 232, 0.08);
}

button {
  padding: 0 14px;
  cursor: pointer;
  font-weight: 850;
}

button:hover {
  background: rgba(244, 240, 232, 0.14);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.primary {
  color: #102016;
  background: var(--power);
  border-color: transparent;
}

.primary:hover {
  background: #79e3b3;
}

.setting {
  display: grid;
  gap: 8px;
}

.home-link {
  display: inline-flex;
  align-items: center;
  min-height: 36px;
  margin-bottom: 18px;
  color: var(--power);
  font-weight: 850;
  text-decoration: none;
}

.home-link:hover {
  text-decoration: underline;
}

label,
.rules h2 {
  color: var(--source);
  font-size: 0.8rem;
  font-weight: 900;
  text-transform: uppercase;
}

select {
  width: 100%;
  padding: 0 12px;
}

.rules {
  margin-top: 22px;
  padding-top: 20px;
  border-top: 1px solid rgba(244, 240, 232, 0.12);
}

.rules p {
  margin-top: 8px;
  color: var(--muted);
  line-height: 1.55;
}

.rules .zh {
  color: #d7dddc;
}

@keyframes hintPulse {
  0%,
  100% {
    box-shadow: inset 0 0 18px rgba(255, 207, 86, 0);
  }

  50% {
    box-shadow: inset 0 0 28px rgba(255, 207, 86, 0.75);
  }
}

@media (max-width: 900px) {
  .shell {
    grid-template-columns: 1fr;
    align-items: start;
  }

  .side-panel {
    order: -1;
  }
}

@media (max-width: 560px) {
  .shell {
    width: min(100vw - 18px, 480px);
    padding: 9px 0 18px;
    gap: 10px;
  }

  .game-panel,
  .side-panel {
    padding: 14px;
  }

  .topbar {
    align-items: stretch;
    flex-direction: column;
    gap: 10px;
  }

  .status-pill {
    width: fit-content;
  }

  .hud,
  .controls {
    gap: 8px;
  }

  button {
    padding: 0 8px;
  }
}