/* ===== CSS Custom Properties ===== */
:root {
  /* Colors — Light mode */
  --bg: #fafafa;
  --bg-secondary: #ffffff;
  --text: #1a1a2e;
  --text-secondary: #555;
  --border: #ddd;

  /* Group colors */
  --yellow: #f9df6d;
  --yellow-text: #5a4a00;
  --green: #a0c35a;
  --green-text: #2a3d00;
  --blue: #b0c4ef;
  --blue-text: #1a2a5e;
  --purple: #ba81c5;
  --purple-text: #3a1a4a;

  /* UI colors */
  --tile-bg: #efefe6;
  --tile-hover: #e0e0d6;
  --tile-selected: #5a594e;
  --tile-selected-text: #ffffff;
  --btn-primary: #1a1a2e;
  --btn-primary-text: #ffffff;
  --btn-secondary-bg: #ffffff;
  --btn-secondary-text: #1a1a2e;
  --btn-secondary-border: #1a1a2e;
  --btn-disabled: #ccc;
  --btn-disabled-text: #888;
  --modal-bg: #ffffff;
  --overlay: rgba(0, 0, 0, 0.5);
  --toast-bg: #1a1a2e;
  --toast-text: #ffffff;
  --mistake-dot: #1a1a2e;
  --mistake-dot-empty: #ccc;

  /* Sizing */
  --max-width: 500px;
  --grid-gap: 8px;
  --radius: 8px;
  --radius-lg: 12px;
}

/* ===== Dark Mode ===== */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #121213;
    --bg-secondary: #1e1e1f;
    --text: #e8e8e8;
    --text-secondary: #aaa;
    --border: #333;

    --tile-bg: #2d2d2f;
    --tile-hover: #3a3a3c;
    --tile-selected: #e8e8e8;
    --tile-selected-text: #121213;
    --btn-primary: #e8e8e8;
    --btn-primary-text: #121213;
    --btn-secondary-bg: transparent;
    --btn-secondary-text: #e8e8e8;
    --btn-secondary-border: #e8e8e8;
    --btn-disabled: #444;
    --btn-disabled-text: #666;
    --modal-bg: #1e1e1f;
    --overlay: rgba(0, 0, 0, 0.7);
    --toast-bg: #e8e8e8;
    --toast-text: #121213;
    --mistake-dot: #e8e8e8;
    --mistake-dot-empty: #444;

    --yellow-text: #3a3000;
    --green-text: #1a2d00;
    --blue-text: #0e1a4e;
    --purple-text: #2a0a3a;
  }
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  display: flex;
  justify-content: center;
  -webkit-user-select: none;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

#app {
  width: 100%;
  max-width: var(--max-width);
  padding: 0 16px 24px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

/* ===== Header ===== */
.header {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 0 12px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 16px;
}

.header-center {
  text-align: center;
}

.title {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.subtitle {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.header-btn {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-secondary);
  color: var(--text);
  font-size: 1.1rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease;
}

@media (hover: hover) {
  .header-btn:hover {
    background: var(--tile-bg);
  }
}

/* ===== Toast ===== */
.toast-container {
  position: fixed;
  top: 80px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 1000;
  pointer-events: none;
}

.toast {
  background: var(--toast-bg);
  color: var(--toast-text);
  padding: 10px 20px;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 600;
  opacity: 0;
  transform: translateY(-10px);
  transition: opacity 0.3s ease, transform 0.3s ease;
  white-space: nowrap;
}

.toast.show {
  opacity: 1;
  transform: translateY(0);
}

/* ===== Solved Groups Area ===== */
.solved-area {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: var(--grid-gap);
}

.solved-row {
  width: 100%;
  border-radius: var(--radius);
  padding: 14px 12px;
  text-align: center;
  animation: solvedAppear 0.5s ease-out forwards;
}

.solved-row.color-yellow { background: var(--yellow); color: var(--yellow-text); }
.solved-row.color-green { background: var(--green); color: var(--green-text); }
.solved-row.color-blue { background: var(--blue); color: var(--blue-text); }
.solved-row.color-purple { background: var(--purple); color: var(--purple-text); }

.solved-category {
  font-weight: 700;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.02em;
}

.solved-words {
  font-size: 0.85rem;
  margin-top: 4px;
  font-weight: 500;
}

@keyframes solvedAppear {
  0% {
    opacity: 0;
    transform: scaleY(0.8);
  }
  100% {
    opacity: 1;
    transform: scaleY(1);
  }
}

/* ===== Game Grid ===== */
.grid {
  width: 100%;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--grid-gap);
  margin-top: var(--grid-gap);
}

.grid:empty {
  margin-top: 0;
}

.tile {
  aspect-ratio: 1 / 0.72;
  background: var(--tile-bg);
  border: none;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  font-size: clamp(0.62rem, 2.8vw, 0.9rem);
  font-weight: 700;
  color: var(--text);
  cursor: pointer;
  padding: 4px 2px;
  line-height: 1.15;
  text-transform: uppercase;
  transition: transform 0.12s ease, background-color 0.15s ease, color 0.15s ease;
  word-break: normal;
  overflow-wrap: anywhere;
}

@media (hover: hover) {
  .tile:hover:not(.selected):not(.disabled) {
    background: var(--tile-hover);
  }
}

.tile.selected {
  background: var(--tile-selected);
  color: var(--tile-selected-text);
  transform: scale(0.95);
}

.tile.disabled {
  pointer-events: none;
  opacity: 0.5;
}

.tile.shake {
  animation: shake 0.4s ease-in-out;
}

.tile.pop {
  animation: pop 0.35s ease-out;
}

.tile.bounce {
  animation: bounce 0.4s ease-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-6px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(4px); }
}

@keyframes pop {
  0% { transform: scale(1); }
  50% { transform: scale(1.1); }
  100% { transform: scale(1); }
}

@keyframes bounce {
  0% { transform: translateY(0); }
  40% { transform: translateY(-8px); }
  100% { transform: translateY(0); }
}

/* ===== Mistakes ===== */
.mistakes {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.mistakes-label {
  font-weight: 500;
}

.mistakes-dots {
  display: flex;
  gap: 6px;
}

.mistake-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--mistake-dot);
  transition: background 0.3s ease, transform 0.3s ease;
}

.mistake-dot.empty {
  background: var(--mistake-dot-empty);
}

.mistake-dot.used {
  animation: dotPulse 0.3s ease-out;
}

@keyframes dotPulse {
  0% { transform: scale(1.4); }
  100% { transform: scale(1); }
}

/* ===== Controls ===== */
.controls {
  display: flex;
  gap: 8px;
  margin-top: 16px;
  width: 100%;
  justify-content: center;
}

.btn {
  padding: 12px 24px;
  border-radius: 24px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: opacity 0.15s ease, transform 0.1s ease;
}

.btn:active {
  transform: scale(0.97);
}

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

.btn-secondary {
  background: var(--btn-secondary-bg);
  color: var(--btn-secondary-text);
  border: 1px solid var(--btn-secondary-border);
}

.btn:disabled {
  background: var(--btn-disabled);
  color: var(--btn-disabled-text);
  border-color: var(--btn-disabled);
  cursor: not-allowed;
  transform: none;
}

@media (hover: hover) {
  .btn:not(:disabled):hover {
    opacity: 0.85;
  }
}

/* ===== Game Over ===== */
.game-over {
  width: 100%;
  margin-top: 20px;
  animation: fadeIn 0.5s ease-out;
}

.game-over[hidden] {
  display: none;
}

.game-over-content {
  text-align: center;
  padding: 24px 16px;
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
}

.game-over-content h2 {
  font-size: 1.3rem;
  margin-bottom: 4px;
}

.game-over-content p {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.game-over-stats {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin: 20px 0;
}

.stat {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
}

.stat-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.game-over-actions {
  margin: 16px 0 12px;
}

.next-puzzle {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

@keyframes fadeIn {
  0% { opacity: 0; transform: translateY(10px); }
  100% { opacity: 1; transform: translateY(0); }
}

/* ===== Modals ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--overlay);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  padding: 16px;
  animation: fadeIn 0.2s ease-out;
}

.modal-overlay[hidden] {
  display: none;
}

.modal {
  background: var(--modal-bg);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  max-width: 400px;
  width: 100%;
  position: relative;
  animation: modalIn 0.25s ease-out;
}

@keyframes modalIn {
  0% { opacity: 0; transform: scale(0.95) translateY(10px); }
  100% { opacity: 1; transform: scale(1) translateY(0); }
}

.modal-close {
  position: absolute;
  top: 12px;
  right: 16px;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-secondary);
  cursor: pointer;
  line-height: 1;
}

.modal h2 {
  font-size: 1.2rem;
  margin-bottom: 16px;
}

/* Tutorial */
.tutorial-body {
  text-align: left;
  font-size: 0.9rem;
  line-height: 1.6;
}

.tutorial-body ul {
  padding-left: 20px;
  margin: 12px 0;
}

.tutorial-body li {
  margin-bottom: 6px;
}

.tutorial-colors {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin: 12px 0;
  font-size: 0.85rem;
  font-weight: 500;
}

.color-chip {
  width: 20px;
  height: 20px;
  border-radius: 4px;
  display: inline-block;
}

.color-chip.color-yellow { background: var(--yellow); }
.color-chip.color-green { background: var(--green); }
.color-chip.color-blue { background: var(--blue); }
.color-chip.color-purple { background: var(--purple); }

.tutorial-note {
  margin-top: 12px;
  font-style: italic;
  color: var(--text-secondary);
}

.tutorial-start {
  width: 100%;
  margin-top: 16px;
}

/* Stats modal */
.stats-grid {
  display: flex;
  justify-content: space-around;
  gap: 12px;
  padding: 16px 0;
}

/* ===== Responsive ===== */
@media (max-width: 360px) {
  .controls {
    gap: 4px;
  }
  .btn {
    padding: 10px 14px;
    font-size: 0.82rem;
  }
  .header {
    padding: 12px 0 10px;
  }
}

/* Safe area for notched phones */
@supports (padding-bottom: env(safe-area-inset-bottom)) {
  #app {
    padding-bottom: calc(24px + env(safe-area-inset-bottom));
  }
}