:root {
  color-scheme: light;
  --bg: #eef1f4;
  --panel: #ffffff;
  --panel-soft: #f8f9fb;
  --ink: #1e252d;
  --muted: #66717d;
  --line: #d9dee5;
  --accent: #167c80;
  --accent-strong: #0f6366;
  --focus: #f2b84b;
  --shadow: 0 18px 42px rgba(30, 37, 45, 0.12);
  --piece-overflow: 44px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 1180px;
  min-height: 100vh;
  overflow: hidden;
  background: var(--bg);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

.app-shell,
.screen {
  height: 100vh;
  min-height: 0;
}

.screen.is-hidden {
  display: none;
}

.gallery-screen {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  gap: 16px;
  overflow: hidden;
  padding: 24px 40px;
}

.gallery-header,
.gallery-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand h1,
.game-heading {
  margin: 0;
  letter-spacing: 0;
}

.brand h1 {
  font-size: 38px;
  line-height: 1;
}

.eyebrow {
  margin: 0 0 7px;
  color: var(--accent-strong);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.gallery-status {
  display: grid;
  gap: 4px;
  min-width: 220px;
  color: var(--muted);
  font-size: 13px;
  text-align: right;
}

.gallery-status strong {
  color: var(--ink);
  font-size: 15px;
}

.gallery-main {
  min-height: 0;
  overflow-y: auto;
  padding-right: 6px;
  overscroll-behavior: contain;
}

.image-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(260px, 1fr));
  grid-auto-rows: clamp(190px, 24vh, 260px);
  gap: 18px;
  min-height: 0;
}

.image-card {
  position: relative;
  height: 100%;
  min-height: 0;
  overflow: hidden;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: inherit;
  box-shadow: 0 10px 26px rgba(30, 37, 45, 0.08);
}

.image-card img {
  display: block;
  width: 100%;
  height: 100%;
  min-height: 0;
  object-fit: cover;
  transition: transform 180ms ease;
}

.image-card:hover img {
  transform: scale(1.025);
}

.image-card.is-selected,
.difficulty-button.is-selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(22, 124, 128, 0.18), 0 12px 28px rgba(30, 37, 45, 0.12);
}

.gallery-footer {
  padding-top: 6px;
}

.difficulty-list {
  display: grid;
  grid-template-columns: repeat(3, 110px);
  gap: 10px;
}

.difficulty-button {
  display: grid;
  gap: 2px;
  min-height: 64px;
  padding: 10px 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: inherit;
  text-align: center;
}

.difficulty-button strong {
  font-size: 21px;
}

.difficulty-button span,
.message,
.progress-pill span {
  color: var(--muted);
}

.difficulty-button span {
  font-size: 11px;
}

.primary-button,
.secondary-button,
.back-button {
  min-height: 42px;
  border-radius: 8px;
  font-weight: 800;
}

.primary-button {
  min-width: 220px;
  border: 0;
  background: var(--accent);
  color: #ffffff;
}

.primary-button:hover {
  background: var(--accent-strong);
}

.secondary-button,
.back-button {
  border: 1px solid var(--line);
  background: #ffffff;
  color: var(--ink);
}

.secondary-button {
  min-width: 96px;
  padding: 0 14px;
}

.back-button {
  min-width: 86px;
}

.primary-button:disabled,
.secondary-button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.game-screen {
  display: grid;
  grid-template-rows: auto minmax(0, 1fr) auto;
  gap: 12px;
  padding: 24px;
}

.game-header {
  display: grid;
  grid-template-columns: auto minmax(260px, 1fr) auto;
  align-items: center;
  gap: 24px;
}

.game-heading {
  justify-self: center;
  max-width: 640px;
  overflow: hidden;
  font-size: 25px;
  line-height: 1.15;
  text-align: center;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.game-controls {
  display: flex;
  align-items: center;
  gap: 12px;
}

.progress-pill {
  display: grid;
  gap: 1px;
  min-width: 104px;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  font-size: 12px;
}

.progress-pill strong {
  font-size: 15px;
}

.toggle-row {
  display: flex;
  align-items: center;
  gap: 8px;
  min-height: 42px;
  padding: 0 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  color: var(--muted);
  font-size: 13px;
}

.toggle-row input {
  width: 17px;
  height: 17px;
  accent-color: var(--accent);
}

.message {
  margin: 0;
  align-self: end;
  padding-top: 2px;
  font-size: 14px;
}

.puzzle-area {
  position: relative;
  display: grid;
  grid-template-columns: max-content minmax(340px, 1fr);
  gap: 24px;
  min-height: 0;
  overflow: hidden;
}

.board-stage {
  position: relative;
  align-self: start;
  overflow: visible;
  padding: var(--piece-overflow);
}

.board {
  position: relative;
  overflow: visible;
  border: 1px solid rgba(30, 37, 45, 0.24);
  border-radius: 8px;
  background: #ffffff;
  box-shadow: var(--shadow);
}

.board-reference {
  position: absolute;
  inset: 0;
  border-radius: 7px;
  background-position: center;
  background-size: cover;
  opacity: 0.15;
  transition: opacity 160ms ease;
}

.board-reference.is-hidden {
  opacity: 0;
}

.piece-tray {
  position: relative;
  min-width: 340px;
  height: 100%;
  min-height: 0;
  overflow: hidden;
  border: 1px dashed #c5ccd5;
  border-radius: 8px;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.76), rgba(255, 255, 255, 0.48)),
    repeating-linear-gradient(135deg, rgba(30, 37, 45, 0.035) 0 8px, transparent 8px 16px);
}

.piece-tray::before {
  content: "Loose pieces";
  position: absolute;
  z-index: 2;
  top: 12px;
  left: 14px;
  padding: 3px 6px;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.82);
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.piece {
  position: absolute;
  display: block;
  touch-action: none;
  filter: drop-shadow(0 6px 7px rgba(30, 37, 45, 0.2));
  transition: filter 120ms ease;
  user-select: none;
  contain: layout style;
}

.piece:hover {
  filter: drop-shadow(0 8px 10px rgba(30, 37, 45, 0.26));
}

.piece.is-dragging {
  filter: drop-shadow(0 14px 18px rgba(30, 37, 45, 0.3));
  will-change: transform;
}

.piece.is-locked {
  cursor: default;
  filter: none;
  pointer-events: none;
  transition: none;
}

.puzzle-area.is-dragging-piece .piece:not(.is-dragging):not(.is-locked),
.puzzle-area.is-high-piece-count .piece,
.puzzle-area.is-high-piece-count .piece:hover {
  filter: none;
  transition: none;
}

.puzzle-area.is-high-piece-count .piece.is-dragging {
  filter: drop-shadow(0 8px 10px rgba(30, 37, 45, 0.26));
}

.completion-banner {
  position: absolute;
  left: 50%;
  top: 50%;
  z-index: 5000;
  display: grid;
  gap: 4px;
  width: min(360px, calc(100% - 48px));
  padding: 18px 20px;
  border: 1px solid rgba(22, 124, 128, 0.3);
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.95);
  box-shadow: var(--shadow);
  text-align: center;
  transform: translate(-50%, -50%);
}

.completion-banner[hidden] {
  display: none;
}

.completion-banner strong {
  font-size: 20px;
}

.completion-banner span {
  color: var(--muted);
  font-size: 13px;
}

button:focus-visible,
input:focus-visible,
.piece:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}