/* ============================================================
   ALGEBRA PUZZLE GAME — style.css
   Warm, tactile, wooden puzzle-board aesthetic
   Fonts: Fredoka One (headings), JetBrains Mono (equations)
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Fredoka+One&family=JetBrains+Mono:wght@400;600;700&family=Nunito:wght@400;600;700;800&display=swap');

/* ─── CSS Variables ──────────────────────────────────────── */
:root {
  --bg:          #1A1208;
  --board-bg:    #2C1A0A;
  --panel-bg:    #3D2410;
  --felt-left:   #1A3A2A;
  --felt-right:  #1A2A3A;
  --felt-border: #2E4A3A;
  --felt-border-r: #2A3A4A;
  --wood:        #5C3317;
  --wood-light:  #7A4520;
  --gold:        #D4A843;
  --gold-glow:   #F0C060;
  --eq-beam:     #8B6914;

  /* Tile colors */
  --tile-unknown: #1A6B5A;
  --tile-unknown-glow: #2ECC9A;
  --tile-const:   #7A3B10;
  --tile-const-light: #C4621A;
  --tile-product: #2A3A7A;
  --tile-product-light: #4A6ADA;
  --tile-neg:     #7A1A2A;
  --tile-neg-light: #D44A5A;
  --tile-star:    #8A6A0A;
  --tile-moon:    #4A3A7A;
  --tile-sun:     #8A4A0A;
  --tile-symbol:  #1A5A4A;

  --text-bright:  #F5E8C0;
  --text-dim:     #A09070;
  --text-accent:  #FFD06A;

  --radius-tile:  12px;
  --radius-panel: 16px;
  --shadow-tile:  0 4px 12px rgba(0,0,0,0.5), inset 0 1px 0 rgba(255,255,255,0.08);
  --shadow-deep:  0 8px 24px rgba(0,0,0,0.7);

  --trans-fast:   0.15s ease;
  --trans-mid:    0.25s ease;
  --trans-slow:   0.4s cubic-bezier(0.34,1.56,0.64,1);
}

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

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  font-family: 'Nunito', sans-serif;
  background: var(--bg);
  color: var(--text-bright);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  /* Subtle wood grain texture */
  background-image:
    repeating-linear-gradient(
      90deg,
      transparent,
      transparent 40px,
      rgba(255,255,255,0.008) 40px,
      rgba(255,255,255,0.008) 41px
    ),
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 80px,
      rgba(0,0,0,0.1) 80px,
      rgba(0,0,0,0.1) 81px
    );
}

/* ─── Header Bar ─────────────────────────────────────────── */
#header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.25rem;
  background: linear-gradient(180deg, var(--panel-bg), var(--board-bg));
  border-bottom: 2px solid var(--wood);
  flex-shrink: 0;
  gap: 0.5rem;
  position: relative;
  z-index: 10;
}

#header-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.game-title {
  font-family: 'Fredoka One', sans-serif;
  font-size: 1.35rem;
  color: var(--gold);
  letter-spacing: 0.02em;
  text-shadow: 0 2px 8px rgba(212, 168, 67, 0.4);
  white-space: nowrap;
}

#tier-badge {
  padding: 0.2rem 0.65rem;
  border-radius: 20px;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #fff;
  opacity: 0.9;
}

#level-info {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  flex: 1;
  min-width: 0;
}

#level-id {
  font-family: 'Fredoka One', sans-serif;
  font-size: 1.1rem;
  color: var(--gold-glow);
  line-height: 1;
}

#stage-label {
  font-size: 0.65rem;
  color: var(--text-dim);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

#level-title {
  font-size: 0.85rem;
  color: var(--text-bright);
  font-weight: 700;
}

#header-right {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Move counter */
#move-counter {
  display: flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.85rem;
  color: var(--text-dim);
  white-space: nowrap;
}

#move-count {
  font-family: 'JetBrains Mono', monospace;
  font-size: 1rem;
  font-weight: 700;
  color: var(--gold);
  min-width: 1.5rem;
  text-align: center;
}

/* Header Buttons */
.hdr-btn {
  background: var(--wood);
  border: 1px solid var(--wood-light);
  color: var(--text-bright);
  border-radius: 8px;
  padding: 0.35rem 0.65rem;
  font-size: 0.8rem;
  font-family: 'Nunito', sans-serif;
  font-weight: 700;
  cursor: pointer;
  transition: background var(--trans-fast), transform var(--trans-fast);
  white-space: nowrap;
}

.hdr-btn:hover {
  background: var(--wood-light);
  transform: translateY(-1px);
}

.hdr-btn:active { transform: translateY(0); }

/* ─── Main Layout ────────────────────────────────────────── */
#main {
  display: flex;
  flex: 1;
  overflow: hidden;
  flex-direction: column;
}

/* Equation preview bar */
#equation-bar {
  padding: 0.4rem 1.25rem;
  background: rgba(0,0,0,0.3);
  border-bottom: 1px solid rgba(255,255,255,0.05);
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

#equation-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-dim);
  white-space: nowrap;
}

#equation-preview {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-accent);
  letter-spacing: 0.05em;
}

/* ─── Board ──────────────────────────────────────────────── */
#board-wrapper {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 1rem 1.25rem 0.75rem;
  overflow: hidden;
}

#board {
  display: flex;
  align-items: stretch;
  gap: 0;
  flex: 1;
  min-height: 0;
  border-radius: var(--radius-panel);
  overflow: hidden;
  box-shadow: var(--shadow-deep);
  transition: transform 0.15s;
}

#board.op-flash {
  animation: op-flash 0.3s ease;
}

@keyframes op-flash {
  0%   { transform: scale(1); }
  50%  { transform: scale(1.01); }
  100% { transform: scale(1); }
}

/* The two sides */
.eq-side {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 1rem 1rem 1rem;
  position: relative;
  overflow: hidden;
}

#left-side-wrap  { background: var(--felt-left);  }
#right-side-wrap { background: var(--felt-right); }

.side-label {
  font-size: 0.65rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: rgba(255,255,255,0.25);
  margin-bottom: 0.5rem;
  text-align: center;
}

.tile-tray {
  flex: 1;
  display: flex;
  flex-wrap: wrap;
  align-content: flex-start;
  gap: 0.6rem;
  padding: 0.5rem;
  border-radius: 10px;
  background: rgba(0,0,0,0.2);
  border: 1px solid rgba(255,255,255,0.06);
  min-height: 80px;
  overflow-y: auto;
  overflow-x: hidden;
}

/* Equals beam */
#eq-beam {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  flex-shrink: 0;
  background: linear-gradient(180deg, var(--board-bg) 0%, var(--eq-beam) 50%, var(--board-bg) 100%);
  position: relative;
}

#eq-beam::before {
  content: '=';
  font-family: 'JetBrains Mono', monospace;
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--gold);
  text-shadow: 0 0 12px rgba(212, 168, 67, 0.6);
}

/* ─── Tiles ──────────────────────────────────────────────── */
.tile {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 52px;
  min-height: 52px;
  padding: 0.4rem 0.65rem;
  border-radius: var(--radius-tile);
  cursor: pointer;
  user-select: none;
  position: relative;
  transition:
    transform var(--trans-slow),
    box-shadow var(--trans-mid),
    opacity var(--trans-mid),
    background var(--trans-fast);
  animation: tile-appear 0.35s cubic-bezier(0.34,1.56,0.64,1);
}

@keyframes tile-appear {
  from { transform: scale(0.3); opacity: 0; }
  to   { transform: scale(1);   opacity: 1; }
}

.tile-label {
  font-family: 'Fredoka One', sans-serif;
  font-size: 1.25rem;
  line-height: 1;
  pointer-events: none;
  text-shadow: 0 1px 3px rgba(0,0,0,0.5);
}

/* Tile type styling */
.tile-unknown {
  background: linear-gradient(135deg, var(--tile-unknown), #0F4A3A);
  border: 2px solid var(--tile-unknown-glow);
  box-shadow: var(--shadow-tile), 0 0 12px rgba(46,204,154,0.2);
  color: #A0FFD0;
}

.tile-constant {
  background: linear-gradient(135deg, var(--tile-const), #4A2008);
  border: 2px solid var(--tile-const-light);
  box-shadow: var(--shadow-tile);
  color: #FFD0A0;
}

.tile-constant.skin-star {
  background: linear-gradient(135deg, #6A5008, #3A2A04);
  border-color: #C0A020;
  color: #FFE06A;
}

.tile-constant.skin-moon {
  background: linear-gradient(135deg, #3A2A6A, #1A1040);
  border-color: #8A70D0;
  color: #D0C0FF;
}

.tile-constant.skin-sun {
  background: linear-gradient(135deg, #6A3A08, #3A1C04);
  border-color: #E08020;
  color: #FFB060;
}

.tile-constant.skin-nstar,
.tile-constant.skin-nmoon {
  background: linear-gradient(135deg, var(--tile-neg), #4A0A14);
  border-color: var(--tile-neg-light);
  color: #FFB0BA;
}

.tile-constant.skin-number {
  background: linear-gradient(135deg, var(--tile-const), #4A2008);
  border: 2px solid var(--tile-const-light);
  color: #FFD0A0;
}

.tile-product {
  background: linear-gradient(135deg, var(--tile-product), #182050);
  border: 2px solid var(--tile-product-light);
  box-shadow: var(--shadow-tile), 0 0 10px rgba(74,106,218,0.2);
  color: #B0C8FF;
  min-width: 64px;
}

.tile-product.skin-symbol {
  background: linear-gradient(135deg, #1A3A5A, #0C1E30);
  border-color: #4A90C0;
  color: #90D0FF;
}

/* Hover */
.tile:hover {
  transform: translateY(-3px) scale(1.05);
  box-shadow: var(--shadow-tile), 0 8px 20px rgba(0,0,0,0.5);
  z-index: 2;
}

.tile:active {
  transform: translateY(-1px) scale(1.02);
}

/* Selected */
.tile.selected {
  transform: translateY(-4px) scale(1.08);
  z-index: 3;
  animation: selected-pulse 1.2s ease-in-out infinite;
}

.tile-unknown.selected {
  box-shadow: var(--shadow-tile), 0 0 0 3px var(--tile-unknown-glow), 0 0 20px rgba(46,204,154,0.5);
}

.tile-constant.selected, .tile-product.selected {
  box-shadow: var(--shadow-tile), 0 0 0 3px var(--gold-glow), 0 0 20px rgba(240,192,96,0.4);
}

@keyframes selected-pulse {
  0%, 100% { box-shadow: var(--shadow-tile), 0 0 0 3px var(--gold-glow), 0 0 15px rgba(240,192,96,0.3); }
  50%       { box-shadow: var(--shadow-tile), 0 0 0 4px var(--gold-glow), 0 0 25px rgba(240,192,96,0.6); }
}

/* Removing animation */
.tile.removing {
  animation: tile-remove 0.32s ease forwards;
}

@keyframes tile-remove {
  0%   { transform: scale(1);    opacity: 1; }
  60%  { transform: scale(1.15); opacity: 0.8; }
  100% { transform: scale(0);    opacity: 0; }
}

/* Shake */
.tile.shake {
  animation: shake 0.4s ease;
}

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

/* Placeholder */
.tile-placeholder {
  color: rgba(255,255,255,0.15);
  font-size: 0.75rem;
  font-style: italic;
  padding: 0.5rem;
  align-self: center;
  pointer-events: none;
}

/* ─── Action Panel ───────────────────────────────────────── */
#action-area {
  padding: 0.75rem 1.25rem 1rem;
  background: var(--board-bg);
  border-top: 2px solid var(--wood);
  flex-shrink: 0;
}

#action-panel {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
}

.action-label {
  font-size: 0.7rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  width: 100%;
}

.action-btn {
  padding: 0.5rem 1rem;
  border-radius: 10px;
  border: 2px solid transparent;
  font-family: 'Nunito', sans-serif;
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--trans-fast);
  letter-spacing: 0.02em;
}

.btn-pair {
  background: linear-gradient(135deg, #1A4A2A, #0C2A18);
  border-color: #2E8A4A;
  color: #90DCA0;
}
.btn-pair:hover { background: linear-gradient(135deg, #2A6A3A, #1A4A28); }

.btn-inverse {
  background: linear-gradient(135deg, #4A3A0A, #2A2008);
  border-color: #C0900A;
  color: #FFD070;
}
.btn-inverse:hover { background: linear-gradient(135deg, #6A5010, #3A2C0A); }

.btn-combine {
  background: linear-gradient(135deg, #1A2A5A, #0C1A3A);
  border-color: #3A60C0;
  color: #90B0FF;
}
.btn-combine:hover { background: linear-gradient(135deg, #2A3A7A, #182A50); }

.divide-row {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.btn-divide {
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  background: linear-gradient(135deg, #2A1A4A, #180E30);
  border: 2px solid #6A4AC0;
  color: #C0A0FF;
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all var(--trans-fast);
}

.btn-divide:hover {
  background: linear-gradient(135deg, #3A2A6A, #201840);
  transform: translateY(-2px);
}

/* ─── Hint Banner ────────────────────────────────────────── */
#hint-banner {
  position: fixed;
  top: 4rem;
  left: 50%;
  transform: translateX(-50%) translateY(-10px);
  background: linear-gradient(135deg, #2A1A00, #1A1000);
  border: 2px solid var(--gold);
  color: var(--gold-glow);
  padding: 0.65rem 1.25rem;
  border-radius: 12px;
  font-size: 0.85rem;
  font-weight: 700;
  max-width: 380px;
  text-align: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s, transform 0.3s;
  z-index: 100;
  box-shadow: 0 4px 20px rgba(212,168,67,0.3);
}

#hint-banner.visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ─── Win Overlay ────────────────────────────────────────── */
#win-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.8);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s;
  backdrop-filter: blur(4px);
}

#win-overlay.visible {
  opacity: 1;
  pointer-events: all;
}

#win-card {
  background: linear-gradient(160deg, #3D2410, #1A1008);
  border: 3px solid var(--gold);
  border-radius: 20px;
  padding: 2rem 2.5rem;
  text-align: center;
  box-shadow: 0 0 60px rgba(212,168,67,0.3), var(--shadow-deep);
  animation: win-pop 0.5s cubic-bezier(0.34,1.56,0.64,1);
  max-width: 320px;
  width: 90%;
}

@keyframes win-pop {
  from { transform: scale(0.5); opacity: 0; }
  to   { transform: scale(1);   opacity: 1; }
}

#win-message {
  font-family: 'Fredoka One', sans-serif;
  font-size: 1.8rem;
  color: var(--gold-glow);
  text-shadow: 0 0 20px rgba(212,168,67,0.5);
  margin-bottom: 0.5rem;
}

#win-stars {
  font-size: 2rem;
  display: block;
  margin: 0.5rem 0;
  animation: star-bounce 0.5s 0.2s cubic-bezier(0.34,1.56,0.64,1);
}

@keyframes star-bounce {
  from { transform: scale(0); }
  to   { transform: scale(1); }
}

#win-moves {
  font-size: 0.9rem;
  color: var(--text-dim);
  margin-bottom: 1.5rem;
}

.win-btns {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
}

.win-btn {
  padding: 0.6rem 1.4rem;
  border-radius: 12px;
  border: 2px solid;
  font-family: 'Nunito', sans-serif;
  font-weight: 800;
  font-size: 1rem;
  cursor: pointer;
  transition: all var(--trans-fast);
}

#win-next-btn {
  background: linear-gradient(135deg, #5A8A3A, #3A6A20);
  border-color: #8ACA50;
  color: #C0FF80;
}
#win-next-btn:hover { background: linear-gradient(135deg, #6AAA48, #4A8030); transform: scale(1.05); }

#win-retry-btn {
  background: linear-gradient(135deg, #5A3A1A, #3A2010);
  border-color: #A07030;
  color: #D4A86A;
}
#win-retry-btn:hover { background: linear-gradient(135deg, #7A5030, #4A2A18); transform: scale(1.05); }

/* ─── Level Nav Drawer ───────────────────────────────────── */
#level-nav {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: 280px;
  background: linear-gradient(180deg, #2C1A0A, #1A1008);
  border-right: 2px solid var(--wood);
  z-index: 150;
  transform: translateX(-100%);
  transition: transform 0.3s cubic-bezier(0.34,1,0.64,1);
  overflow-y: auto;
  padding: 1rem;
}

#level-nav.open {
  transform: translateX(0);
  box-shadow: 4px 0 30px rgba(0,0,0,0.6);
}

.tier-section { margin-bottom: 1.25rem; }

.tier-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.75rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-dim);
  margin-bottom: 0.5rem;
  padding-bottom: 0.35rem;
  border-bottom: 2px solid;
}

.tier-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.level-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.35rem;
}

.level-btn {
  padding: 0.35rem 0.2rem;
  background: var(--panel-bg);
  border: 1px solid var(--wood);
  border-radius: 6px;
  color: var(--text-dim);
  font-size: 0.6rem;
  font-family: 'JetBrains Mono', monospace;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--trans-fast);
  text-align: center;
}

.level-btn:hover {
  background: var(--wood);
  color: var(--text-bright);
  transform: scale(1.05);
}

.level-btn.active {
  background: var(--gold);
  color: #1A1008;
  border-color: var(--gold-glow);
  box-shadow: 0 0 8px rgba(212,168,67,0.4);
}

/* ─── Confetti ───────────────────────────────────────────── */
#confetti-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  pointer-events: none;
  z-index: 300;
  overflow: hidden;
  height: 100vh;
}

.confetti-piece {
  position: absolute;
  top: -20px;
  animation: confetti-fall linear forwards;
}

@keyframes confetti-fall {
  0%   { transform: translateY(0) rotate(0deg);   opacity: 1; }
  80%  { opacity: 1; }
  100% { transform: translateY(110vh) rotate(720deg); opacity: 0; }
}

/* ─── Scrollbar ──────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: rgba(0,0,0,0.2); }
::-webkit-scrollbar-thumb { background: var(--wood-light); border-radius: 3px; }

/* ─── Responsive ─────────────────────────────────────────── */
@media (max-width: 600px) {
  .game-title { font-size: 1rem; }
  #level-id { font-size: 0.9rem; }
  .tile { min-width: 44px; min-height: 44px; }
  .tile-label { font-size: 1rem; }
  #board-wrapper { padding: 0.5rem 0.5rem 0.5rem; }
  #action-area { padding: 0.5rem 0.75rem 0.75rem; }
  #eq-beam { width: 36px; }
  #eq-beam::before { font-size: 1.2rem; }
  .action-btn { font-size: 0.75rem; padding: 0.4rem 0.75rem; }
}