:root {
  --ink: oklch(25% 0.025 100);
  --ink-soft: oklch(43% 0.025 100);
  --paper: oklch(96.5% 0.012 94);
  --paper-deep: oklch(92.5% 0.02 92);
  --line: oklch(38% 0.025 95 / 32%);
  --line-strong: oklch(27% 0.03 98 / 82%);
  --accent: oklch(47% 0.115 49);
  --accent-dark: oklch(37% 0.09 49);
  --success: oklch(42% 0.09 151);
  --danger: oklch(48% 0.15 25);
  --focus: oklch(48% 0.16 240);
  --radius-small: 4px;
  --radius-medium: 7px;
  --space-2xs: 4px;
  --space-xs: 8px;
  --space-sm: 12px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --board-size: min(calc(100vw - 24px), 70dvh, 680px);
  color-scheme: light;
  font-family:
    ui-sans-serif,
    system-ui,
    -apple-system,
    BlinkMacSystemFont,
    "Segoe UI",
    sans-serif;
  color: var(--ink);
  background: var(--paper);
  font-synthesis: none;
  text-rendering: optimizeLegibility;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  min-width: 320px;
  background: var(--paper);
}

body {
  min-height: 100dvh;
  margin: 0;
  background:
    var(--paper);
}

button {
  font: inherit;
}

button {
  color: inherit;
}

.app-shell {
  width: min(100%, 1100px);
  min-height: 100dvh;
  margin: 0 auto;
  padding:
    max(var(--space-md), env(safe-area-inset-top))
    max(var(--space-sm), env(safe-area-inset-right))
    max(var(--space-lg), env(safe-area-inset-bottom))
    max(var(--space-sm), env(safe-area-inset-left));
}

.masthead {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: var(--space-xl);
  width: min(100%, 970px);
  margin: 0 auto var(--space-lg);
}

.eyebrow,
.section-label {
  margin: 0 0 var(--space-2xs);
  color: var(--ink-soft);
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0;
  font-size: clamp(1.85rem, 5vw, 2.7rem);
  line-height: 1;
  letter-spacing: -0.045em;
}

h1 span {
  display: inline-block;
  margin-right: 0.14em;
  font-family:
    "Apple Color Emoji",
    "Segoe UI Emoji",
    "Noto Color Emoji",
    sans-serif;
  font-size: 0.88em;
  transform: rotate(-5deg);
}

.rule-summary {
  max-width: 42ch;
  margin-bottom: 0;
  color: var(--ink-soft);
  font-size: 0.92rem;
  line-height: 1.5;
}

.game-layout {
  display: grid;
  grid-template-columns: minmax(0, auto);
  justify-content: center;
  gap: var(--space-lg);
}

.board-area {
  display: grid;
  justify-items: center;
  gap: var(--space-sm);
  min-width: 0;
}

.board {
  display: grid;
  grid-template-columns: repeat(var(--grid-size), minmax(0, 1fr));
  grid-template-rows: repeat(var(--grid-size), minmax(0, 1fr));
  width: var(--board-size);
  height: var(--board-size);
  overflow: hidden;
  border: 2px solid var(--line-strong);
  border-radius: 6px;
  background: var(--paper-deep);
  box-shadow:
    0 2px 4px oklch(20% 0.02 90 / 10%),
    0 18px 45px oklch(38% 0.035 85 / 10%);
  touch-action: manipulation;
  user-select: none;
  -webkit-user-select: none;
}

.cell {
  position: relative;
  display: grid;
  min-width: 0;
  min-height: 0;
  place-items: center;
  padding: 0;
  overflow: hidden;
  appearance: none;
  border: 0;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  border-radius: 0;
  background-color: var(--cell-color);
  background-image: var(--cell-pattern);
  background-size: var(--cell-pattern-size);
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition:
    filter 120ms ease-out,
    transform 120ms ease-out;
}

.cell.boundary-right {
  border-right: 3px solid var(--line-strong);
}

.cell.boundary-bottom {
  border-bottom: 3px solid var(--line-strong);
}

.cell.edge-right {
  border-right: 0;
}

.cell.edge-bottom {
  border-bottom: 0;
}

.cell:hover:not(:disabled) {
  filter: brightness(0.965) saturate(1.08);
}

.cell:active:not(:disabled) {
  transform: scale(0.96);
}

.cell:disabled {
  cursor: default;
  opacity: 1;
}

.cell::after {
  position: absolute;
  display: grid;
  place-items: center;
  line-height: 1;
  pointer-events: none;
}

.cell[data-state="cross"]::after {
  content: "×";
  color: oklch(27% 0.02 96 / 68%);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: clamp(1rem, calc(var(--board-size) / 19), 2.25rem);
  font-weight: 460;
}

.cell[data-state="duck"]::after,
.cell.is-revealed::after {
  content: "🦆";
  font-family:
    "Apple Color Emoji",
    "Segoe UI Emoji",
    "Noto Color Emoji",
    sans-serif;
  font-size: clamp(1rem, calc(var(--board-size) / 15), 2.8rem);
  filter: drop-shadow(0 1px 0 oklch(20% 0 0 / 16%));
}

.cell.is-revealed::after {
  opacity: 0;
  animation: reveal-duck 280ms ease-out forwards;
}

.cell.is-incorrect::before {
  content: "!";
  position: absolute;
  z-index: 1;
  display: grid;
  width: 52%;
  aspect-ratio: 1;
  place-items: center;
  border-radius: 50%;
  color: oklch(96% 0.01 25);
  background: var(--danger);
  font-size: clamp(0.72rem, calc(var(--board-size) / 24), 1.4rem);
  font-weight: 850;
  line-height: 1;
}

.cell.is-new-duck::after {
  animation: place-duck 300ms cubic-bezier(0.22, 1, 0.36, 1);
}

.cell.is-incorrect {
  z-index: 1;
  animation: wrong-cell 300ms ease-out;
}

.board.is-victory {
  animation: victory-board 360ms ease-out;
}

.interaction-hint {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-xs) var(--space-lg);
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.78rem;
}

.interaction-hint strong {
  color: var(--ink);
  font-weight: 720;
}

.control-panel {
  display: grid;
  align-content: start;
  gap: var(--space-lg);
  width: min(100%, 680px);
  padding-top: var(--space-lg);
  border-top: 1px solid var(--line);
}

.status-block {
  display: grid;
  gap: var(--space-sm);
}

.status h2 {
  margin-bottom: var(--space-2xs);
  font-size: 1.25rem;
  line-height: 1.2;
  letter-spacing: -0.025em;
}

.status p {
  max-width: 48ch;
  margin-bottom: 0;
  color: var(--ink-soft);
  font-size: 0.88rem;
  line-height: 1.5;
}

.status[data-kind="won"] h2 {
  color: var(--success);
}

.status[data-kind="lost"] h2,
.status[data-kind="error"] h2 {
  color: var(--danger);
}

.identity-block {
  min-width: 0;
}

.identity-block code {
  display: block;
  overflow: hidden;
  color: var(--ink);
  font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
  font-size: 0.92rem;
  font-weight: 650;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.copy-feedback {
  min-height: 1.2em;
  margin: var(--space-2xs) 0 0;
  color: var(--success);
  font-size: 0.75rem;
}

.main-actions,
.outcome-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.button {
  min-height: 44px;
  padding: 0.65rem 1rem;
  border: 1px solid transparent;
  border-radius: var(--radius-small);
  font-size: 0.84rem;
  font-weight: 720;
  line-height: 1.1;
  cursor: pointer;
  transition:
    background-color 120ms ease-out,
    border-color 120ms ease-out,
    transform 120ms ease-out;
}

.button:active:not(:disabled) {
  transform: translateY(1px);
}

.button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}

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

.button-primary {
  color: oklch(96% 0.012 80);
  background: var(--accent);
}

.button-primary:hover:not(:disabled) {
  background: var(--accent-dark);
}

.button-secondary {
  border-color: var(--line-strong);
  background: transparent;
}

.button-secondary:hover:not(:disabled),
.button-quiet:hover:not(:disabled) {
  background: var(--paper-deep);
}

.button-quiet {
  border-color: transparent;
  background: transparent;
  color: var(--ink-soft);
}

.rules {
  display: grid;
  gap: var(--space-xs);
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--line);
  border-radius: var(--radius-small);
  background: oklch(94.5% 0.016 93 / 48%);
  font-size: 0.82rem;
}

.rules h2 {
  margin: 0;
  color: var(--ink);
  font-size: 0.74rem;
  font-weight: 760;
  letter-spacing: 0.07em;
  line-height: 1.2;
  text-transform: uppercase;
}

.rules ul {
  display: grid;
  gap: var(--space-2xs);
  margin: 0;
  padding-left: 1.25rem;
  color: var(--ink-soft);
  font-style: italic;
  line-height: 1.45;
}

.board-error {
  display: grid;
  width: var(--board-size);
  height: var(--board-size);
  place-items: center;
  padding: var(--space-xl);
  border: 2px dashed var(--line-strong);
  border-radius: 6px;
  color: var(--ink-soft);
  text-align: center;
}

.clipboard-helper {
  position: fixed;
  top: -1000px;
  left: -1000px;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@keyframes place-duck {
  0% {
    opacity: 0;
    transform: scale(0.6) rotate(-8deg);
  }
  100% {
    opacity: 1;
    transform: scale(1) rotate(0);
  }
}

@keyframes reveal-duck {
  from {
    opacity: 0;
    transform: scale(0.86);
  }
  to {
    opacity: 0.72;
    transform: scale(1);
  }
}

@keyframes wrong-cell {
  0%,
  100% {
    transform: translateX(0);
  }
  25% {
    transform: translateX(-6%);
  }
  75% {
    transform: translateX(6%);
  }
}

@keyframes victory-board {
  0%,
  100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.008);
  }
}

@media (min-width: 880px) {
  :root {
    --board-size: min(66vw, calc(100dvh - 130px), 680px);
  }

  .app-shell {
    display: grid;
    align-content: center;
    padding-top: max(var(--space-lg), env(safe-area-inset-top));
  }

  .game-layout {
    grid-template-columns: minmax(0, auto) 250px;
    align-items: center;
    gap: clamp(var(--space-xl), 5vw, 64px);
  }

  .control-panel {
    width: 250px;
    padding: 0;
    border-top: 0;
  }

  .masthead {
    margin-bottom: var(--space-md);
  }

  .main-actions {
    display: grid;
    grid-template-columns: 1fr 1fr;
  }

  .main-actions .button-quiet {
    grid-column: 1 / -1;
  }
}

@media (max-width: 520px) {
  :root {
    --board-size: min(calc(100vw - 24px), 66dvh, 680px);
  }

  .masthead {
    display: grid;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
  }

  .rule-summary {
    font-size: 0.82rem;
  }

  .control-panel {
    gap: var(--space-md);
    padding-top: var(--space-md);
  }

  .main-actions .button,
  .outcome-actions .button {
    flex: 1 1 0;
  }
}

@media (max-height: 560px) and (orientation: landscape) {
  :root {
    --board-size: min(64vw, calc(100dvh - 86px), 680px);
  }

  .app-shell {
    padding-top: var(--space-xs);
  }

  .masthead {
    margin-bottom: var(--space-xs);
  }

  .eyebrow,
  .rule-summary {
    display: none;
  }

  .interaction-hint {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 1ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 1ms !important;
  }
}