/* ============================================================
   Guiyu -- style.css
   Premium minimalist puzzle-game UI
   ============================================================ */

/* ----------------------------------------------------------
   0. CSS Custom Properties
   ---------------------------------------------------------- */
:root {
  /* Surface & background */
  --bg: #F5F3EE;
  --board-bg: #E8E4DD;
  --pit-fill: #D4CFC6;
  --pit-stroke: #C5BFB4;
  --pit-shadow: #B8B2A6;

  /* Typography */
  --text: #5A5650;
  --text-light: #8A847C;

  /* Accent & interactive */
  --accent: #7BA7BC;
  --btn-bg: #E8E4DD;
  --btn-hover: #DDD8CF;
  --success: #8FBC7B;

  /* Piece palette */
  --piece-1: #7BA7BC;
  --piece-2: #BC7B8F;
  --piece-3: #8FBC7B;
  --piece-4: #BCB07B;
  --piece-5: #9B7BBC;
  --piece-6: #7BBCB0;
  --piece-7: #BC957B;
  --piece-8: #7B8FBC;
  --piece-9: #BC7BAA;
  --piece-10: #A0BC7B;
  --piece-11: #7BBCA0;
  --piece-12: #BC7B7B;

  /* Layout tokens */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-pill: 999px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,.08);
  --shadow-lg: 0 8px 24px rgba(0,0,0,.12);
  --transition-fast: 150ms ease;
  --transition-normal: 250ms ease;
  --transition-slow: 400ms ease;

  /* Board geometry (mirrors SHARED_INTERFACE) */
  --spacing-x: 50;
  --spacing-y: 43;
  --circle-r: 20;

  /* Error feedback */
  --invalid: #c0635a;
}

/* ----------------------------------------------------------
   1. Reset & Base
   ---------------------------------------------------------- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  min-height: 100dvh;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    Oxygen, Ubuntu, Cantarell, 'Helvetica Neue', sans-serif;
  font-weight: 400;
  color: var(--text);
  background: var(--bg);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  outline: none;
  background: none;
  color: inherit;
}

button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* ----------------------------------------------------------
   2. App Shell
   ---------------------------------------------------------- */
#app {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  min-height: 100vh;
  min-height: 100dvh;
  padding: 18px 20px 36px;
  gap: 18px;
  position: relative;
}

.screen {
  width: min(100%, 1120px);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.screen--selection {
  max-width: 1040px;
}

.screen--play {
  max-width: 1180px;
}

.screen--inactive {
  display: none;
}

.screen--enter {
  animation: screen-enter 240ms cubic-bezier(.22,1,.36,1);
}

@keyframes screen-enter {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ----------------------------------------------------------
   3. Header
   ---------------------------------------------------------- */
#header {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  width: 100%;
}

.header-copy {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  padding-top: 8px;
  text-align: center;
}

.header-copy__eyebrow {
  font-size: 0.68rem;
  font-weight: 500;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-light);
}

.header-copy__subtitle {
  max-width: 520px;
  font-size: 0.84rem;
  line-height: 1.55;
  color: var(--text-light);
}

.game-title {
  font-size: 1.02rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--text-light);
  text-transform: uppercase;
  user-select: none;
}

/* ----------------------------------------------------------
   4. Level Selector
   ---------------------------------------------------------- */
#level-selector {
  width: 100%;
  display: grid;
  gap: 10px;
}

.level-selector__summary {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 16px;
}

.level-selector__meta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.level-selector__copy {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.level-selector__eyebrow {
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-light);
}

.level-selector__title {
  font-size: 0.98rem;
  font-weight: 600;
  color: var(--text);
}

.level-selector__subtitle {
  font-size: 0.78rem;
  color: var(--text-light);
}

.level-selector__count {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 28px;
  padding: 0 12px;
  border-radius: var(--radius-pill);
  background: rgba(255,255,255,.62);
  color: var(--text-light);
  font-size: 0.72rem;
  box-shadow: inset 0 1px 0 rgba(255,255,255,.45);
}

.play-header {
  width: 100%;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  padding: 4px 2px 0;
}

.play-header__back {
  flex-shrink: 0;
}

.play-header__copy {
  min-width: 0;
  flex: 1 1 auto;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.play-header__eyebrow {
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-light);
}

.play-header__title {
  font-size: 1.18rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
}

.play-header__meta {
  max-width: 700px;
  font-size: 0.8rem;
  line-height: 1.45;
  color: var(--text-light);
}

.level-tabs {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px;
  border-radius: 999px;
  background: rgba(255,255,255,.42);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.55);
  width: fit-content;
  max-width: 100%;
}

.level-tab {
  min-width: 88px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 999px;
  color: var(--text-light);
  transition: background var(--transition-fast),
              color var(--transition-fast),
              box-shadow var(--transition-fast);
}

.level-tab:hover {
  color: var(--text);
}

.level-tab--active {
  background: rgba(123,167,188,.16);
  color: var(--text);
  box-shadow: 0 6px 14px rgba(123,167,188,.12);
}

.level-tab__label {
  font-size: 0.78rem;
  font-weight: 600;
}

.level-tab__count {
  min-width: 20px;
  height: 20px;
  padding: 0 6px;
  border-radius: 999px;
  background: rgba(232,228,221,.9);
  font-size: 0.68rem;
}

.level-card {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 14px 16px;
  text-align: left;
  background: rgba(255,255,255,.5);
  border: 1px solid rgba(255,255,255,.5);
  border-radius: 18px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast),
              box-shadow var(--transition-fast),
              border-color var(--transition-fast),
              background var(--transition-fast);
}

.level-card:hover {
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
  background: rgba(255,255,255,.68);
}

.level-card--active,
.level-card--active:hover {
  border-color: rgba(123,167,188,.45);
  background: rgba(244,249,251,.88);
  box-shadow: 0 8px 24px rgba(123,167,188,.16);
}

.level-card--finale {
  border-color: rgba(188,149,123,.26);
  background: linear-gradient(180deg, rgba(252,249,245,.96), rgba(247,241,233,.92));
  box-shadow: 0 10px 24px rgba(188,149,123,.1);
}

.level-card__top,
.level-card__footer,
.level-card__meta,
.level-card__top-meta,
.level-card__tags {
  display: flex;
  align-items: center;
}

.level-card__top,
.level-card__footer {
  justify-content: space-between;
  gap: 12px;
}

.level-card__top-meta {
  gap: 8px;
  flex-wrap: wrap;
}

.level-card__number,
.level-card__board,
.level-card__badge,
.level-card__tag,
.guide-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-pill);
}

.level-card__number {
  min-width: 28px;
  height: 28px;
  padding: 0 10px;
  background: rgba(123,167,188,.12);
  color: var(--text);
  font-size: 0.74rem;
  font-weight: 600;
}

.level-card__board {
  padding: 5px 10px;
  background: rgba(232,228,221,.92);
  color: var(--text-light);
  font-size: 0.72rem;
  letter-spacing: 0.01em;
}

.level-card__badge {
  padding: 5px 10px;
  background: rgba(188,149,123,.14);
  color: var(--text);
  font-size: 0.68rem;
  letter-spacing: 0.04em;
}

.level-card__body {
  display: grid;
  grid-template-columns: minmax(76px, 96px) minmax(0, 1fr);
  gap: 12px;
  align-items: center;
}

.level-card__preview {
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 8px;
  border-radius: 12px;
  background: rgba(232,228,221,.62);
}

.level-card__preview-svg {
  width: 100%;
  height: 58px;
}

.level-card__preview-svg circle {
  fill: rgba(123,167,188,.5);
  stroke: rgba(123,167,188,.2);
  stroke-width: 1;
}

.level-card__copy {
  display: flex;
  flex-direction: column;
  gap: 5px;
  min-width: 0;
}

.level-card__name {
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text);
}

.level-card__description {
  font-size: 0.74rem;
  color: var(--text-light);
  line-height: 1.4;
}

.level-card__meta {
  gap: 6px;
  font-size: 0.72rem;
  color: var(--text-light);
}

.level-card__tags {
  gap: 6px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.level-card__tag {
  padding: 4px 9px;
  background: rgba(255,255,255,.72);
  color: var(--text-light);
  font-size: 0.69rem;
}

/* ----------------------------------------------------------
   5. Game Area
   ---------------------------------------------------------- */
#game-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex-wrap: wrap;
  gap: 32px;
  width: 100%;
  max-width: 640px;
}

/* ----------------------------------------------------------
   6. Board Container
   ---------------------------------------------------------- */
#board-container {
  position: relative;
  width: 100%;
  max-width: 360px;
  background: var(--board-bg);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md),
              inset 0 1px 0 rgba(255,255,255,.45);
  padding: 28px 20px 32px;
  display: flex;
  align-items: center;
  justify-content: center;
}

#board-svg {
  display: block;
  width: 100%;
  height: auto;
  overflow: visible;
}

/* SVG pit circles (styled via attributes in JS, but class fallbacks here) */
#board-pits circle {
  fill: var(--pit-fill);
  stroke: var(--pit-stroke);
  stroke-width: 1;
  filter: url(#pit-shadow);
  transition: fill var(--transition-fast),
              stroke var(--transition-fast);
}

#board-highlights circle {
  fill: var(--accent);
  opacity: 0;
  transition: opacity var(--transition-fast);
  pointer-events: none;
}

#board-pieces circle {
  filter: url(#piece-glow);
  transition: fill var(--transition-fast),
              opacity var(--transition-normal);
}

/* Pit states */
.pit--highlight {
  fill: var(--accent) !important;
  opacity: 0.30 !important;
  stroke: var(--accent) !important;
}

.pit--occupied {
  stroke-width: 0.5 !important;
  stroke: rgba(0,0,0,.08) !important;
}

.pit--invalid {
  fill: var(--invalid) !important;
  opacity: 0.35 !important;
  stroke: var(--invalid) !important;
}

.pit--candidate-invalid {
  fill: rgba(192, 99, 90, 0.20) !important;
  stroke: rgba(192, 99, 90, 0.55) !important;
}

/* Highlight circles shown during drag snap preview */
.snap-preview {
  opacity: 0.35 !important;
  transition: opacity 120ms ease, transform 120ms ease;
}

.snap-preview--legal {
  opacity: 0.6 !important;
}

.snap-preview--invalid {
  opacity: 0.34 !important;
}

.snap-preview--ring {
  opacity: 0.75 !important;
}

/* ----------------------------------------------------------
   7. Loading Message
   ---------------------------------------------------------- */
.loading-message {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  pointer-events: none;
}

.loading-message--error {
  padding: 18px;
  text-align: center;
  color: var(--ink-strong);
  font-size: 0.9rem;
  line-height: 1.5;
  background: linear-gradient(180deg, rgba(255,255,255,.52), rgba(255,255,255,.28));
  backdrop-filter: blur(6px);
}

.loading-message.hidden {
  display: none;
}

.loading-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--pit-stroke);
  animation: loading-pulse 1.2s ease-in-out infinite;
}

.loading-dot:nth-child(2) { animation-delay: 0.15s; }
.loading-dot:nth-child(3) { animation-delay: 0.30s; }

@keyframes loading-pulse {
  0%, 80%, 100% { opacity: 0.3; transform: scale(0.8); }
  40% { opacity: 1; transform: scale(1); }
}

/* ----------------------------------------------------------
   8. Pieces Tray
   ---------------------------------------------------------- */
#pieces-tray {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(88px, 1fr));
  gap: 12px;
  width: 100%;
  max-width: 560px;
  padding: 6px;
  min-height: 60px;
  grid-auto-rows: 1fr;
  align-content: start;
}

.piece-wrapper {
  display: grid;
  place-items: center;
  min-height: 92px;
  padding: 8px;
  background: rgba(255,255,255,.45);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  cursor: grab;
  transition: box-shadow var(--transition-normal),
              transform var(--transition-normal),
              opacity var(--transition-normal);
  user-select: none;
  touch-action: none;
  position: relative;
  contain: layout paint;
  overflow: hidden;
}

.piece-wrapper:hover {
  box-shadow: var(--shadow-md);
}

.piece-wrapper:active {
  cursor: grabbing;
}

.piece-svg {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  max-height: 100%;
  margin: auto;
  overflow: visible;
  pointer-events: none;
  flex: 0 0 auto;
}

#pieces-tray.pieces-tray--dense {
  gap: 10px;
  max-height: min(42vh, 430px);
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-gutter: stable both-edges;
}

#pieces-tray.pieces-tray--crowded {
  grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
}

#pieces-tray.pieces-tray--crowded .piece-wrapper {
  min-height: 84px;
  padding: 7px;
}

.piece-svg circle {
  filter: url(#piece-glow);
  stroke: rgba(255,255,255,.35);
  stroke-width: 0.8;
}

/* Piece states */
.piece--dragging {
  box-shadow: var(--shadow-md) !important;
  z-index: 1000;
  opacity: 0.96;
  cursor: grabbing;
  position: fixed;
  pointer-events: none;
  will-change: transform;
}

html.drag-scroll-locked,
body.drag-scroll-locked {
  overflow: hidden;
  overscroll-behavior: none;
}

.piece--placed {
  opacity: 0.35;
  pointer-events: auto;
  box-shadow: none;
  transform: scale(0.92);
  filter: grayscale(0.3);
  cursor: grab;
}

.piece--suggested {
  background: rgba(255,255,255,.8);
  box-shadow: 0 8px 24px rgba(123,167,188,.18);
  transform: translateY(-1px);
}

.piece--selected {
  background: rgba(244,249,251,.92);
  box-shadow: 0 10px 24px rgba(123,167,188,.16);
}

.piece--ghost {
  opacity: 0;
  pointer-events: none;
  position: absolute;
}

#board-pieces .board-piece {
  cursor: grab;
  touch-action: none;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

#board-pieces .board-piece:hover {
  transform: translateY(-1px);
}

#board-pieces .board-piece--selected circle {
  stroke: rgba(255,255,255,.72);
  stroke-width: 1.1;
  filter: url(#highlight-glow);
}

.guide-preview {
  pointer-events: none;
}

.guide-preview--focus {
  animation: guide-pulse 1.8s ease-in-out infinite;
}

@keyframes guide-pulse {
  0%, 100% { opacity: 0.34; }
  50% { opacity: 0.62; }
}

/* ----------------------------------------------------------
   8b. Play Hint Bar
   ---------------------------------------------------------- */
#play-hint-bar {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  border: 0;
  clip: rect(0, 0, 0, 0);
  clip-path: inset(50%);
  white-space: nowrap;
}

.play-hint-bar {
  min-height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border-radius: var(--radius-pill);
  background: rgba(255,255,255,.42);
  color: var(--text-light);
  box-shadow: var(--shadow-sm);
  transition: background var(--transition-fast),
              color var(--transition-fast),
              box-shadow var(--transition-fast),
              transform var(--transition-fast);
  text-align: center;
}

.play-hint-bar__text {
  font-size: 0.78rem;
  line-height: 1.35;
  letter-spacing: 0.01em;
}

.play-hint-bar--active {
  background: rgba(255,255,255,.62);
  color: var(--text);
}

.play-hint-bar--success {
  background: rgba(143,188,123,.18);
  color: var(--text);
  box-shadow: 0 4px 14px rgba(143,188,123,.12);
}

.play-hint-bar--warning {
  background: rgba(192,99,90,.14);
  color: var(--text);
  box-shadow: 0 4px 14px rgba(192,99,90,.1);
}

/* ----------------------------------------------------------
   9. Controls
   ---------------------------------------------------------- */
#controls {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
  width: 100%;
  max-width: 820px;
  align-self: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  min-height: 40px;
  font-size: 0.8rem;
  font-weight: 500;
  border-radius: var(--radius-pill);
  transition: background var(--transition-fast),
              color var(--transition-fast),
              box-shadow var(--transition-fast);
  touch-action: manipulation;
}

.btn--subtle {
  background: var(--btn-bg);
  color: var(--text-light);
}

.btn--subtle:hover {
  background: var(--btn-hover);
  color: var(--text);
}

.btn--subtle:active {
  background: #d3cec5;
}

.btn--accent {
  background: var(--accent);
  color: #fff;
}

.btn--accent:hover {
  background: #6b99ad;
  box-shadow: 0 2px 8px rgba(123,167,188,.35);
}

.btn--accent:active {
  background: #5e8a9c;
}

.btn-icon {
  flex-shrink: 0;
}

.guide-shell {
  width: 100%;
  max-width: 820px;
  order: 4;
  align-self: center;
}

.guide-panel {
  position: relative;
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 18px 18px 16px;
  border-radius: 22px;
  background: rgba(255,255,255,.84);
  box-shadow: 0 14px 34px rgba(79,74,67,.08);
  border: 1px solid rgba(255,255,255,.78);
  overflow: auto;
}

.guide-panel__top,
.guide-panel__meta,
.guide-panel__actions {
  display: flex;
  align-items: center;
}

.guide-panel__top {
  justify-content: space-between;
  gap: 12px;
}

.guide-panel__eyebrow {
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-light);
}

.guide-panel__close {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: rgba(232,228,221,.86);
  color: var(--text-light);
}

.guide-panel__close:hover {
  background: rgba(221,216,207,.96);
  color: var(--text);
}

.guide-panel__content {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.guide-panel__title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text);
}

.guide-panel__description {
  font-size: 0.84rem;
  line-height: 1.5;
  color: var(--text-light);
}

.guide-panel__meta {
  gap: 8px;
  flex-wrap: wrap;
}

.guide-chip {
  padding: 5px 10px;
  background: rgba(232,228,221,.76);
  font-size: 0.72rem;
  color: var(--text-light);
}

.guide-panel__actions {
  gap: 10px;
  justify-content: flex-end;
  flex-wrap: wrap;
}

.guide-panel__actions .btn:disabled {
  opacity: 0.45;
  cursor: default;
}

/* ----------------------------------------------------------
   10. Celebration Overlay
   ---------------------------------------------------------- */
#celebration-overlay {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity var(--transition-slow);
}

#celebration-overlay.hidden {
  display: none;
}

#celebration-overlay.fade-out {
  opacity: 0;
  pointer-events: none;
}

/* Backdrop */
.celebration-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(245,243,238,.82);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  animation: backdrop-in 400ms ease forwards;
}

.celebration-backdrop::before,
.celebration-backdrop::after {
  content: '';
  position: absolute;
  inset: auto;
  pointer-events: none;
}

.celebration-backdrop::before {
  left: 50%;
  top: 18%;
  width: min(62vw, 620px);
  height: min(42vw, 340px);
  translate: -50% 0;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255,255,255,.52), rgba(255,255,255,0) 72%);
  opacity: .9;
}

.celebration-backdrop::after {
  left: 50%;
  bottom: 8%;
  width: min(80vw, 760px);
  height: 120px;
  translate: -50% 0;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(123,167,188,.12), rgba(123,167,188,0) 72%);
}

@keyframes backdrop-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Win message */
.win-message {
  position: relative;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 26px 30px;
  border-radius: 28px;
  background: linear-gradient(180deg, rgba(255,255,255,.84), rgba(255,255,255,.7));
  box-shadow: 0 20px 48px rgba(90,86,80,.1);
  border: 1px solid rgba(255,255,255,.82);
  overflow: hidden;
  animation: win-enter 600ms cubic-bezier(.22,1,.36,1) forwards;
}

.win-message::before,
.win-message::after {
  content: '';
  position: absolute;
  inset: 0;
  pointer-events: none;
}

.win-message::before {
  inset: 1px;
  border-radius: 27px;
  background: linear-gradient(180deg, rgba(255,255,255,.42), rgba(255,255,255,0));
}

.win-message::after {
  inset: auto 18px 10px;
  height: 24px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(123,167,188,.16), rgba(123,167,188,0) 72%);
}

.win-message__title {
  position: relative;
  z-index: 1;
  font-size: 2.4rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text);
}

.win-message__subtitle {
  position: relative;
  z-index: 1;
  font-size: 1rem;
  font-weight: 400;
  color: var(--text-light);
  margin-bottom: 8px;
}

.win-message__btn {
  position: relative;
  z-index: 1;
  margin-top: 12px;
  padding: 10px 28px;
  font-size: 0.9rem;
}

@keyframes win-enter {
  0% {
    opacity: 0;
    transform: scale(0.85) translateY(16px);
  }
  100% {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

/* ----------------------------------------------------------
   11. Cannons
   ---------------------------------------------------------- */
.cannon {
  position: fixed;
  bottom: -6px;
  z-index: 2001;
  width: 76px;
  height: 108px;
  animation: cannon-appear 500ms cubic-bezier(.34,1.56,.64,1) forwards;
  transform-origin: bottom center;
}

.cannon::before {
  content: '';
  position: absolute;
  left: 50%;
  bottom: 8px;
  width: 66px;
  height: 42px;
  translate: -50% 0;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255,255,255,.28), rgba(255,255,255,0) 72%);
  pointer-events: none;
}

.cannon-left {
  left: 10%;
  transform: scale(0) rotate(15deg);
}

.cannon-right {
  right: 10%;
  transform: scale(0) rotate(-15deg);
}

.cannon-body {
  position: absolute;
  bottom: 14px;
  left: 50%;
  translate: -50% 0;
  width: 42px;
  height: 44px;
  background: linear-gradient(180deg, #77828a, #56626b 64%, #4a545d);
  border-radius: 14px 14px 16px 16px;
  box-shadow: 0 12px 20px rgba(90,86,80,.16),
              inset 0 1px 0 rgba(255,255,255,.18);
}

.cannon-body::before,
.cannon-body::after,
.cannon-barrel::before,
.cannon-base::after,
.cannon-mouth::before,
.cannon-mouth::after {
  content: '';
  position: absolute;
}

.cannon-body::before {
  inset: 6px 7px auto;
  height: 9px;
  border-radius: 999px;
  background: linear-gradient(180deg, rgba(255,255,255,.34), rgba(255,255,255,0));
}

.cannon-body::after {
  left: 50%;
  bottom: 8px;
  translate: -50% 0;
  width: 18px;
  height: 6px;
  border-radius: 999px;
  background: rgba(245,243,238,.48);
}

.cannon-base {
  position: absolute;
  bottom: 0;
  left: 50%;
  translate: -50% 0;
  width: 56px;
  height: 20px;
  border-radius: 999px;
  background: linear-gradient(180deg, rgba(236,232,226,.98), rgba(199,193,183,.92));
  box-shadow: 0 10px 22px rgba(90,86,80,.12);
}

.cannon-base::after {
  inset: 2px 8px auto;
  height: 5px;
  border-radius: 999px;
  background: rgba(255,255,255,.42);
}

.cannon-shadow {
  position: absolute;
  bottom: 4px;
  left: 50%;
  translate: -50% 0;
  width: 72px;
  height: 22px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(90,86,80,.18), rgba(90,86,80,0));
  filter: blur(1px);
}

.cannon-band {
  position: absolute;
  bottom: 28px;
  left: 50%;
  translate: -50% 0;
  width: 28px;
  height: 10px;
  border-radius: 999px;
  background: linear-gradient(180deg, rgba(249,247,243,.84), rgba(218,212,203,.72));
  box-shadow: inset 0 1px 0 rgba(255,255,255,.42);
}

.cannon-barrel {
  position: absolute;
  bottom: 42px;
  left: 50%;
  translate: -50% 0;
  width: 24px;
  height: 54px;
  background: linear-gradient(180deg, #929da7, #72808a 58%, #62717b);
  border-radius: 12px 12px 8px 8px;
  box-shadow: inset 0 -8px 14px rgba(0,0,0,.08),
              inset 0 1px 0 rgba(255,255,255,.3),
              0 8px 16px rgba(90,86,80,.1);
}

.cannon-barrel::before {
  top: 6px;
  left: 50%;
  translate: -50% 0;
  width: 14px;
  height: 5px;
  border-radius: 999px;
  background: rgba(255,255,255,.3);
}

.cannon-mouth {
  position: absolute;
  bottom: 88px;
  left: 50%;
  translate: -50% 0;
  width: 18px;
  height: 14px;
  border-radius: 999px;
  background: radial-gradient(circle at 50% 38%, #e5dfd6, #73808a 60%, #4a555d 100%);
  box-shadow: 0 3px 8px rgba(90,86,80,.12);
}

.cannon-mouth::before {
  inset: -10px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255,246,217,.65), rgba(255,246,217,0) 72%);
  opacity: 0;
}

.cannon-mouth::after {
  left: 50%;
  top: -4px;
  translate: -50% 0;
  width: 26px;
  height: 20px;
  border-radius: 50% 50% 42% 42%;
  background: radial-gradient(circle at 50% 35%, rgba(255,255,255,.92), rgba(255,231,186,.74) 54%, rgba(255,224,171,0) 78%);
  opacity: 0;
  transform-origin: center center;
}

.cannon-left .cannon-barrel,
.cannon-left .cannon-mouth {
  transform: rotate(15deg);
  transform-origin: bottom center;
}

.cannon-right .cannon-barrel,
.cannon-right .cannon-mouth {
  transform: rotate(-15deg);
  transform-origin: bottom center;
}

.cannon--arming .cannon-barrel,
.cannon--arming .cannon-mouth {
  animation: cannon-prep 180ms ease-out forwards;
}

.cannon--firing .cannon-body {
  animation: cannon-recoil-body 360ms cubic-bezier(.2,.9,.3,1) forwards;
}

.cannon--firing .cannon-barrel,
.cannon--firing .cannon-mouth {
  animation: cannon-recoil-barrel 360ms cubic-bezier(.2,.9,.3,1) forwards;
}

.cannon--firing .cannon-mouth::before {
  animation: cannon-bloom 300ms ease-out forwards;
}

.cannon--firing .cannon-mouth::after {
  animation: cannon-flare 280ms ease-out forwards;
}

@keyframes cannon-prep {
  0% { translate: -50% 0; }
  100% { translate: -50% -5px; }
}

@keyframes cannon-recoil-body {
  0% { transform: translateY(0) scale(1); }
  28% { transform: translateY(2px) scale(.985); }
  72% { transform: translateY(-2px) scale(1.01); }
  100% { transform: translateY(0) scale(1); }
}

@keyframes cannon-recoil-barrel {
  0% { translate: -50% 0; }
  20% { translate: -50% -8px; }
  55% { translate: -50% 2px; }
  100% { translate: -50% 0; }
}

@keyframes cannon-bloom {
  0% { opacity: 0; transform: scale(.4); }
  28% { opacity: .88; transform: scale(1); }
  100% { opacity: 0; transform: scale(1.6); }
}

@keyframes cannon-flare {
  0% { opacity: 0; transform: scale(.6); }
  24% { opacity: .8; transform: scale(1); }
  100% { opacity: 0; transform: scale(1.45); }
}

@keyframes cannon-appear {
  0% {
    transform: scale(0) rotate(var(--cannon-rot, 0deg));
    opacity: 0;
  }
  100% {
    transform: scale(1) rotate(var(--cannon-rot, 0deg));
    opacity: 1;
  }
}

.cannon-left  { --cannon-rot: 15deg; }
.cannon-right { --cannon-rot: -15deg; }

/* ----------------------------------------------------------
   12. Confetti
   ---------------------------------------------------------- */
.confetti-container {
  position: fixed;
  inset: 0;
  z-index: 2002;
  pointer-events: none;
  overflow: hidden;
}

.confetti-particle {
  position: absolute;
  width: 8px;
  height: 8px;
  border-radius: 2px;
  opacity: 0;
  animation: confetti-burst var(--confetti-duration, 2.2s) ease-out forwards;
  animation-delay: var(--confetti-delay, 0s);
}

.confetti-particle--circle {
  border-radius: 50%;
  width: 7px;
  height: 7px;
}

.confetti-particle--rect {
  border-radius: 1px;
  width: 6px;
  height: 10px;
}

@keyframes confetti-burst {
  0% {
    opacity: 1;
    transform: translate(0, 0) rotate(0deg) scale(1);
  }
  15% {
    opacity: 1;
  }
  100% {
    opacity: 0;
    transform:
      translate(var(--confetti-x, 60px), var(--confetti-y, -320px))
      rotate(var(--confetti-spin, 720deg))
      scale(0.4);
  }
}

/* Second stage: confetti that falls down after launch */
.confetti-particle--falling {
  animation: confetti-fall var(--confetti-duration, 3s) ease-in forwards;
  animation-delay: var(--confetti-delay, 0.4s);
}

@keyframes confetti-fall {
  0% {
    opacity: 1;
    transform: translate(var(--fall-start-x, 0px), var(--fall-start-y, -100px))
               rotate(0deg);
  }
  100% {
    opacity: 0;
    transform: translate(
                 calc(var(--fall-start-x, 0px) + var(--fall-drift, 30px)),
                 calc(100vh + 40px)
               )
               rotate(var(--confetti-spin, 540deg));
  }
}

/* ----------------------------------------------------------
   13. Utility Classes
   ---------------------------------------------------------- */
.hidden {
  display: none !important;
}

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

/* ----------------------------------------------------------
   13b. Settings
   ---------------------------------------------------------- */
.settings-shell {
  position: fixed;
  top: 18px;
  right: 18px;
  z-index: 120;
}

.btn-settings {
  position: relative;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--btn-bg);
  border-radius: 50%;
  color: var(--text-light);
  transition: background var(--transition-fast), color var(--transition-fast), box-shadow var(--transition-fast);
  box-shadow: 0 8px 18px rgba(79,74,67,.08);
  z-index: 100;
  padding: 0;
}

.btn-settings:hover,
.btn-settings--active {
  background: var(--btn-hover);
  color: var(--text);
}

.settings-panel {
  position: absolute;
  top: 46px;
  right: 0;
  width: min(244px, calc(100vw - 28px));
  display: grid;
  gap: 12px;
  padding: 14px;
  border-radius: 20px;
  background: rgba(255,255,255,.92);
  border: 1px solid rgba(255,255,255,.82);
  box-shadow: 0 18px 34px rgba(79,74,67,.12);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transform-origin: top right;
  transition: opacity 180ms ease, transform 180ms ease;
}

.settings-panel.hidden {
  opacity: 0;
  pointer-events: none;
  transform: translateY(-6px) scale(0.97);
}

.settings-panel__section {
  display: grid;
  gap: 8px;
}

.settings-panel__label {
  font-size: 0.66rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-light);
}

.settings-segment {
  display: inline-grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 6px;
}

.settings-segment__btn,
.settings-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 34px;
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(232,228,221,.88);
  color: var(--text);
  font-size: 0.76rem;
  font-weight: 500;
  transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
}

.settings-segment__btn:hover,
.settings-toggle:hover,
.settings-segment__btn--active {
  background: rgba(215,229,237,.95);
  color: #466474;
}

.settings-toggles {
  display: grid;
  gap: 6px;
}

.settings-actions {
  display: grid;
  gap: 6px;
}

.settings-panel__section--play {
  display: none;
}

.settings-toggle--off {
  background: rgba(232,228,221,.54);
  color: var(--text-light);
}

/* ----------------------------------------------------------
   13c. Level Groups (difficulty-based grouping)
   ---------------------------------------------------------- */
.level-group {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 10px;
  padding: 14px;
  border-radius: 20px;
  background: rgba(255,255,255,.32);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.4);
}

.level-group__label {
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--text-light);
  text-transform: uppercase;
  letter-spacing: 0.09em;
}

.level-group__subtitle {
  font-size: 0.82rem;
  color: var(--text-light);
  line-height: 1.45;
}

.level-group__cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 10px;
}

/* ----------------------------------------------------------
   14. Responsive -- Tablet & up (wider layout)
   ---------------------------------------------------------- */
@media (min-width: 768px) {
  #app {
    padding: 20px 28px 44px;
    gap: 20px;
  }

  .screen {
    gap: 20px;
  }

  #game-area {
    flex-direction: row;
    align-items: flex-start;
    justify-content: center;
    gap: 28px;
    max-width: 920px;
  }

  #board-container {
    max-width: 420px;
    flex-shrink: 0;
  }

  #pieces-tray {
    grid-template-columns: repeat(auto-fill, minmax(95px, 1fr));
    gap: 16px;
    max-width: 340px;
    align-self: flex-start;
    padding: 12px;
    background: rgba(255,255,255,.25);
    border-radius: var(--radius-lg);
  }

  #pieces-tray.pieces-tray--dense {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    max-width: 392px;
    max-height: min(52vh, 470px);
    padding: 10px 8px 10px 10px;
  }

  #pieces-tray.pieces-tray--crowded .piece-wrapper {
    min-height: 82px;
  }

  #play-hint-bar {
    max-width: 820px;
  }

  .guide-shell {
    max-width: 820px;
  }

  .game-title {
    font-size: 1.08rem;
  }

  .play-header {
    align-items: center;
  }

  .level-group__cards {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* ----------------------------------------------------------
   15. Responsive -- Large desktop
   ---------------------------------------------------------- */
@media (min-width: 1100px) {
  #app {
    padding: 18px 40px 52px;
  }

  .play-header {
    padding-right: 6px;
  }

  #game-area {
    max-width: 1260px;
  }

  #board-container {
    max-width: 440px;
    padding: 26px 20px 28px;
  }

  #pieces-tray {
    grid-template-columns: repeat(3, 1fr);
    max-width: 360px;
  }

  #pieces-tray.pieces-tray--dense {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    max-width: 424px;
    max-height: min(56vh, 500px);
  }

  .level-group__cards {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .guide-shell {
    order: 3;
    width: 300px;
    max-width: 300px;
    align-self: flex-start;
    position: sticky;
    top: 18px;
  }

  .guide-panel {
    max-height: 72vh;
  }

  #play-hint-bar {
    order: 4;
    max-width: 1128px;
  }

}

/* ----------------------------------------------------------
   16. Responsive -- Small mobile
   ---------------------------------------------------------- */
@media (max-width: 480px) {
  #app {
    padding: calc(14px + env(safe-area-inset-top, 0px)) 12px calc(28px + env(safe-area-inset-bottom, 0px));
    gap: 16px;
  }

  .screen {
    gap: 16px;
  }

  .header-copy {
    padding-top: 2px;
    gap: 5px;
  }

  .header-copy__subtitle {
    font-size: 0.76rem;
    max-width: none;
  }

  .game-title {
    font-size: 0.94rem;
  }

  .level-selector__summary {
    align-items: start;
    flex-direction: column;
    gap: 10px;
  }

  .level-selector__meta {
    justify-content: flex-start;
  }

  .level-selector__eyebrow {
    font-size: 0.62rem;
  }

  .level-selector__title {
    font-size: 0.9rem;
  }

  .level-selector__subtitle {
    font-size: 0.72rem;
  }

  .level-tabs {
    width: 100%;
    justify-content: space-between;
    overflow-x: auto;
    padding: 3px;
    gap: 6px;
    scrollbar-width: none;
  }

  .level-tabs::-webkit-scrollbar {
    display: none;
  }

  .level-tab {
    min-width: 82px;
    padding: 7px 10px;
  }

  .level-group {
    padding: 12px;
  }

  .level-group__cards {
    display: grid;
    grid-auto-flow: column;
    grid-auto-columns: minmax(220px, 76vw);
    overflow-x: auto;
    overscroll-behavior-x: contain;
    scroll-snap-type: x proximity;
    padding-bottom: 2px;
  }

  .level-card {
    scroll-snap-align: start;
    min-height: 146px;
  }

  .level-card__body {
    grid-template-columns: 88px minmax(0, 1fr);
    gap: 10px;
  }

  .level-card__name {
    font-size: 0.9rem;
  }

  .level-card__description {
    font-size: 0.74rem;
  }

  .btn-settings {
    width: 38px;
    height: 38px;
  }

  .play-header {
    flex-direction: column;
    align-items: stretch;
    gap: 12px;
    padding-top: 0;
  }

  .play-header__back {
    align-self: flex-start;
  }

  .play-header__title {
    font-size: 1.02rem;
  }

  .play-header__meta {
    font-size: 0.74rem;
  }

  #board-container {
    padding: 18px 12px 20px;
    border-radius: var(--radius-md);
  }

  #pieces-tray {
    grid-template-columns: repeat(auto-fill, minmax(76px, 1fr));
    gap: 10px;
    padding-bottom: calc(10px + env(safe-area-inset-bottom, 0px));
  }

  .piece-wrapper {
    min-height: 80px;
    padding: 7px;
    border-radius: var(--radius-sm);
  }

  #pieces-tray.pieces-tray--dense {
    max-height: min(34vh, 280px);
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  #pieces-tray.pieces-tray--crowded .piece-wrapper {
    min-height: 74px;
    padding: 6px;
  }

  .btn {
    padding: 7px 14px;
    font-size: 0.75rem;
    min-height: 44px;
    justify-content: center;
  }

  #controls {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 10px;
    width: 100%;
  }

  #controls .rotation-bar {
    grid-column: 1 / -1;
  }

  .guide-shell {
    position: sticky;
    bottom: calc(10px + env(safe-area-inset-bottom, 0px));
    z-index: 18;
    max-width: none;
  }

  .guide-panel {
    border-radius: 20px;
    padding: 14px 14px 12px;
    gap: 12px;
    max-height: 36vh;
  }

  .guide-panel__actions {
    justify-content: stretch;
  }

  .guide-panel__actions .btn {
    flex: 1 1 0;
    justify-content: center;
  }

  .guide-panel__description {
    font-size: 0.78rem;
  }

  .guide-panel__close,
  .settings-segment__btn,
  .settings-toggle {
    min-height: 40px;
  }

  .cannon {
    width: 58px;
    height: 84px;
  }

  .cannon-base {
    width: 42px;
    height: 16px;
  }

  .cannon-body {
    width: 34px;
    height: 34px;
    bottom: 12px;
  }

  .cannon-band {
    width: 22px;
    bottom: 23px;
  }

  .cannon-barrel {
    width: 18px;
    height: 40px;
    bottom: 34px;
  }

  .cannon-mouth {
    width: 13px;
    height: 11px;
    bottom: 65px;
  }

  .win-message__title {
    font-size: 1.8rem;
  }

  .win-message__subtitle {
    font-size: 0.88rem;
  }
}

/* ----------------------------------------------------------
   16b. Responsive -- Mobile portrait play layout
   ---------------------------------------------------------- */
@media (max-width: 767px) and (orientation: portrait) {
  #app.app--play-view .settings-panel__section--play {
    display: grid;
  }

  #app {
    padding: calc(14px + env(safe-area-inset-top, 0px)) 12px calc(28px + env(safe-area-inset-bottom, 0px));
    gap: 12px;
  }

  .screen {
    gap: 12px;
  }

  .screen--selection {
    gap: 12px;
  }

  #header {
    align-items: stretch;
    gap: 12px;
    padding-right: 0;
  }

  .header-copy {
    align-items: flex-start;
    text-align: left;
    padding-top: 0;
    padding-right: 44px;
    gap: 4px;
  }

  .header-copy__subtitle {
    max-width: none;
    font-size: 0.76rem;
    line-height: 1.48;
  }

  .game-title {
    font-size: 0.96rem;
  }

  #level-selector {
    gap: 8px;
  }

  .level-selector__summary {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .level-selector__meta {
    justify-content: flex-start;
    width: 100%;
  }

  .level-tabs {
    width: 100%;
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 7px;
    overflow: visible;
  }

  .level-tab {
    min-width: 0;
    width: 100%;
    padding: 8px 6px;
    justify-content: center;
    gap: 6px;
  }

  .level-tab__label {
    font-size: 0.72rem;
  }

  .level-tab__count {
    min-width: 18px;
    height: 18px;
    font-size: 0.62rem;
  }

  .level-group {
    padding: 0;
    gap: 8px;
    background: transparent;
    box-shadow: none;
    border-radius: 0;
  }

  .level-group__cards {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    grid-auto-flow: row;
    grid-auto-columns: auto;
    gap: 10px;
    overflow: visible;
    scroll-snap-type: none;
    padding-bottom: 0;
  }

  .level-card {
    min-height: 0;
    padding: 13px 12px;
    border-radius: 18px;
    box-shadow: 0 6px 14px rgba(79,74,67,.08);
    transition: border-color var(--transition-fast), background var(--transition-fast);
    content-visibility: auto;
    contain-intrinsic-size: 176px;
  }

  .level-card__body {
    grid-template-columns: 92px minmax(0, 1fr);
    gap: 12px;
  }

  .level-card__preview {
    min-height: 72px;
    padding: 10px;
  }

  .level-card__preview-svg {
    height: 62px;
  }

  .screen--play {
    min-height: calc(100dvh - env(safe-area-inset-top, 0px) - env(safe-area-inset-bottom, 0px) - 16px);
    padding-bottom: calc(116px + env(safe-area-inset-bottom, 0px));
    gap: 12px;
  }

  .play-header {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr);
    align-items: start;
    gap: 8px 10px;
    padding: 0;
  }

  .play-header__back {
    min-height: 40px;
    padding-inline: 12px;
    align-self: start;
  }

  .play-header__copy {
    gap: 2px;
    padding-right: 44px;
    padding-top: 2px;
  }

  .play-header__eyebrow {
    font-size: 0.62rem;
    letter-spacing: 0.08em;
  }

  .play-header__title {
    font-size: 1rem;
    line-height: 1.2;
  }

  .play-header__meta {
    max-width: none;
    font-size: 0.72rem;
    line-height: 1.38;
  }

  #game-area {
    width: 100%;
    max-width: 520px;
    gap: 12px;
    align-items: stretch;
    flex-wrap: nowrap;
    flex: 0 0 auto;
  }

  #board-container {
    order: 1;
    width: min(100%, 460px);
    max-width: none;
    align-self: center;
    padding: 16px 12px 18px;
    border-radius: 18px;
  }

  #board-svg {
    max-height: min(44dvh, 400px);
  }

  #pieces-tray {
    order: 2;
    width: 100%;
    max-width: none;
    align-self: stretch;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 8px;
    padding: 8px 0 4px;
    min-height: 132px;
    max-height: none;
    overflow: visible;
    overscroll-behavior: auto;
    background: transparent;
    border: 0;
    border-radius: 0;
    box-shadow: none;
  }

  .piece-wrapper {
    min-height: 82px;
    padding: 6px;
    box-shadow: 0 4px 12px rgba(79,74,67,.07);
    transition: transform 140ms ease, opacity 140ms ease, background var(--transition-fast);
  }

  #pieces-tray.pieces-tray--dense {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 8px;
    max-height: none;
    padding: 6px 0 4px;
  }

  #pieces-tray.pieces-tray--dense .piece-wrapper {
    min-height: 72px;
    padding: 5px;
  }

  #pieces-tray.pieces-tray--crowded {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  #pieces-tray.pieces-tray--crowded .piece-wrapper {
    min-height: 68px;
    padding: 5px;
  }

  .guide-shell {
    order: 3;
    position: static;
    bottom: auto;
    z-index: auto;
    width: 100%;
    max-width: none;
  }

  .guide-panel {
    gap: 10px;
    padding: 12px 14px;
    border-radius: 18px;
    max-height: min(24dvh, 210px);
    box-shadow: 0 10px 24px rgba(79,74,67,.08);
  }

  .guide-panel__title {
    font-size: 1rem;
  }

  .guide-panel__description {
    font-size: 0.74rem;
    line-height: 1.42;
  }

  .guide-panel__actions {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 8px;
    justify-content: stretch;
  }

  #btn-guide-toggle {
    grid-column: 1 / -1;
  }

  #controls {
    position: fixed;
    left: 50%;
    bottom: max(10px, env(safe-area-inset-bottom, 0px));
    z-index: 18;
    width: min(calc(100% - 24px), 520px);
    transform: translateX(-50%);
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
    padding: 12px 0 calc(2px + env(safe-area-inset-bottom, 0px));
    background: linear-gradient(
      180deg,
      rgba(245,243,238,0),
      rgba(245,243,238,.92) 24%,
      rgba(245,243,238,.98) 100%
    );
  }

  #btn-hint,
  #btn-guide,
  #btn-reset,
  #btn-restart {
    display: none;
  }

  #controls .rotation-bar {
    width: 100%;
    min-height: 64px;
    padding: 10px 10px 10px 12px;
    border-radius: 18px;
  }

  .rotation-bar__title {
    font-size: 0.66rem;
  }

  .rotation-bar__keys {
    max-width: none;
    font-size: 0.58rem;
  }

  .rotation-btn {
    width: 52px;
    height: 52px;
    border-radius: 15px;
  }

  .settings-shell {
    top: calc(12px + env(safe-area-inset-top, 0px));
    right: max(12px, env(safe-area-inset-right, 0px));
  }

  .btn-settings {
    width: 42px;
    height: 42px;
  }

  .settings-panel {
    top: 44px;
    width: min(228px, calc(100vw - 20px));
    box-shadow: 0 12px 24px rgba(79,74,67,.12);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}

/* ----------------------------------------------------------
   17. Reduced motion
   ---------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* ----------------------------------------------------------
   18. Dark-mode hint (for future use)
   ---------------------------------------------------------- */
@media (prefers-color-scheme: dark) {
  /* Intentionally blank -- the warm palette is designed for light.
     A dark theme can be layered later by reassigning the custom properties. */
}

/* ----------------------------------------------------------
   19. Rotation Bar (mobile floating toolbar)
   ---------------------------------------------------------- */
.rotation-bar {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 12px 10px 14px;
  background: rgba(255,255,255,.94);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: 18px;
  border: 1px solid rgba(255,255,255,.88);
  box-shadow: 0 12px 28px rgba(79,74,67,.14);
  transition: opacity 180ms ease, transform 180ms ease, box-shadow 180ms ease;
  width: min(100%, 320px);
  min-height: 58px;
}

.rotation-bar--inactive {
  opacity: 0.74;
  box-shadow: 0 10px 22px rgba(79,74,67,.08);
}

.rotation-bar--active {
  box-shadow: 0 14px 28px rgba(79,74,67,.14);
}

.rotation-bar__hint {
  display: flex;
  flex-direction: column;
  gap: 0;
  margin-right: 2px;
  min-width: 0;
}

.rotation-bar__title {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: 0.02em;
}

.rotation-bar__keys {
  max-width: 180px;
  font-size: 0.62rem;
  line-height: 1.3;
  color: var(--text-light);
}

.rotation-btn {
  width: 42px;
  height: 42px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 14px;
  padding: 0;
}

.rotation-btn:active {
  transform: scale(0.92);
}

.rotation-btn:disabled {
  opacity: 0.45;
  cursor: default;
}

@media (max-width: 640px) {
  .rotation-bar {
    width: 100%;
    gap: 8px;
    padding: 10px 10px 10px 12px;
    min-height: 62px;
    box-shadow: 0 8px 18px rgba(79,74,67,.12);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }

  .rotation-bar__hint {
    margin-right: 0;
  }

  .rotation-bar__title {
    font-size: 0.64rem;
  }

  .rotation-bar__keys {
    display: block;
    max-width: 132px;
    font-size: 0.56rem;
  }

  .rotation-btn {
    width: 50px;
    height: 50px;
  }

  .settings-shell {
    top: calc(14px + env(safe-area-inset-top, 0px));
    right: max(14px, env(safe-area-inset-right, 0px));
  }

  .btn-settings {
    width: 38px;
    height: 38px;
  }

  .settings-panel {
    top: 42px;
    width: min(228px, calc(100vw - 20px));
    padding: 12px;
  }
}