:root {
  --bg-deep:      #0b0716;
  --bg-card:      #160f28;
  --bg-card-2:    #1c1336;
  --purple:       #a855f7;
  --purple-bright:#c084fc;
  --purple-dim:   #6d28d9;
  --violet-glow:  rgba(168,85,247,0.35);
  --text-main:    #f4f1fb;
  --text-muted:   #a597c4;
  --border:       rgba(168,85,247,0.25);

  --cell-bg: rgba(255,255,255,0.04);

  /* tile palette */
  --t2:    #e2d8f5; --t2-txt:    #2d1b69;
  --t4:    #c4b0ee; --t4-txt:    #2d1b69;
  --t8:    #a78bfa; --t8-txt:    #fff;
  --t16:   #818cf8; --t16-txt:   #fff;
  --t32:   #6366f1; --t32-txt:   #fff;
  --t64:   #c084fc; --t64-txt:   #fff;
  --t128:  #e879f9; --t128-txt:  #fff;
  --t256:  #f472b6; --t256-txt:  #fff;
  --t512:  #fb7185; --t512-txt:  #fff;
  --t1024: #fbbf24; --t1024-txt: #1a0a00;
  --t2048: #f59e0b; --t2048-txt: #1a0a00;
  --tsuper:#fff;    --tsuper-txt:#2d1b69;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  min-height: 100vh;
  background:
    radial-gradient(circle at 20% 15%, rgba(168,85,247,0.18), transparent 45%),
    radial-gradient(circle at 85% 85%, rgba(124,58,237,0.16), transparent 50%),
    var(--bg-deep);
  font-family: 'Inter', sans-serif;
  color: var(--text-main);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px 16px;
}

.app {
  width: 100%;
  max-width: 460px;
  position: relative;
}

.panel {
  background: linear-gradient(160deg, var(--bg-card) 0%, var(--bg-card-2) 100%);
  border: 1px solid var(--border);
  border-radius: 24px;
  padding: 24px 22px 22px;
  box-shadow:
    0 0 0 1px rgba(255,255,255,0.02) inset,
    0 30px 60px -20px rgba(0,0,0,0.6),
    0 0 60px -15px var(--violet-glow);
  position: relative;
  overflow: hidden;
}

.panel::before {
  content: "";
  position: absolute;
  top: -60%; left: -20%;
  width: 140%; height: 140%;
  background: conic-gradient(from 180deg, transparent, var(--violet-glow), transparent 35%);
  animation: spin 18s linear infinite;
  opacity: 0.28;
  pointer-events: none;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* ── HEADER ── */
header { margin-bottom: 16px; position: relative; z-index: 1; }

.header-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}

h1 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 38px;
  font-weight: 700;
  background: linear-gradient(90deg, var(--purple-bright), var(--purple), #818cf8);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  background-size: 200% auto;
  animation: shimmer 4s ease-in-out infinite;
  line-height: 1;
}

@keyframes shimmer {
  0%,100% { background-position: 0% 50%; }
  50%      { background-position: 100% 50%; }
}

.score-cluster {
  display: flex;
  gap: 8px;
}

.score-box {
  background: rgba(0,0,0,0.25);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 6px 14px;
  text-align: center;
  min-width: 72px;
}

.score-label {
  display: block;
  font-size: 9px;
  text-transform: uppercase;
  letter-spacing: 0.8px;
  color: var(--text-muted);
  font-weight: 600;
  margin-bottom: 2px;
}

.score-value {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 20px;
  font-weight: 700;
  color: var(--purple-bright);
  transition: transform 0.2s;
  display: block;
}

.score-value.bump { animation: bump 0.32s ease; }
@keyframes bump { 0% { transform: scale(1); } 45% { transform: scale(1.3); } 100% { transform: scale(1); } }

.header-sub {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.subtitle { font-size: 13px; color: var(--text-muted); }
.subtitle strong { color: var(--purple-bright); }

.new-game-btn {
  background: linear-gradient(135deg, var(--purple), var(--purple-dim));
  border: none;
  color: white;
  font-weight: 700;
  font-size: 12px;
  padding: 7px 16px;
  border-radius: 10px;
  cursor: pointer;
  box-shadow: 0 0 16px -4px var(--violet-glow);
  transition: transform 0.15s, box-shadow 0.2s;
}

.new-game-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 22px -2px var(--violet-glow);
}

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

/* ── BOARD ── */
.board-wrap {
  position: relative;
  z-index: 1;
  margin-bottom: 14px;
}

.board {
  position: relative;
  background: rgba(0,0,0,0.35);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 10px;
  box-shadow: inset 0 0 30px rgba(0,0,0,0.4), 0 0 30px -12px var(--violet-glow);
}

.board-bg {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

.cell {
  aspect-ratio: 1;
  background: var(--cell-bg);
  border-radius: 10px;
  border: 1px solid rgba(255,255,255,0.04);
}

.tiles-layer {
  position: absolute;
  inset: 10px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  pointer-events: none;
}

/* ── TILES ── */
.tile {
  position: absolute;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  font-family: 'Space Grotesk', sans-serif;
  font-weight: 700;
  transition: left 0.1s ease, top 0.1s ease;
  -webkit-user-select: none;
  user-select: none;
}

.tile.new   { animation: tileAppear 0.18s cubic-bezier(.34,1.56,.64,1); }
.tile.merge { animation: tileMerge  0.2s  cubic-bezier(.34,1.56,.64,1); }

@keyframes tileAppear {
  0%   { transform: scale(0); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}

@keyframes tileMerge {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.2); }
  100% { transform: scale(1); }
}

/* tile value → style */
.tile[data-val="2"]    { background: var(--t2);    color: var(--t2-txt);    font-size: clamp(18px,5vw,24px); }
.tile[data-val="4"]    { background: var(--t4);    color: var(--t4-txt);    font-size: clamp(18px,5vw,24px); }
.tile[data-val="8"]    { background: var(--t8);    color: var(--t8-txt);    font-size: clamp(18px,5vw,24px); box-shadow: 0 0 16px rgba(167,139,250,0.5); }
.tile[data-val="16"]   { background: var(--t16);   color: var(--t16-txt);   font-size: clamp(16px,4.5vw,22px); box-shadow: 0 0 18px rgba(129,140,248,0.5); }
.tile[data-val="32"]   { background: var(--t32);   color: var(--t32-txt);   font-size: clamp(16px,4.5vw,22px); box-shadow: 0 0 20px rgba(99,102,241,0.55); }
.tile[data-val="64"]   { background: var(--t64);   color: var(--t64-txt);   font-size: clamp(16px,4.5vw,22px); box-shadow: 0 0 22px rgba(192,132,252,0.6); }
.tile[data-val="128"]  { background: var(--t128);  color: var(--t128-txt);  font-size: clamp(14px,4vw,20px);   box-shadow: 0 0 24px rgba(232,121,249,0.65); }
.tile[data-val="256"]  { background: var(--t256);  color: var(--t256-txt);  font-size: clamp(14px,4vw,20px);   box-shadow: 0 0 26px rgba(244,114,182,0.65); }
.tile[data-val="512"]  { background: var(--t512);  color: var(--t512-txt);  font-size: clamp(14px,4vw,20px);   box-shadow: 0 0 28px rgba(251,113,133,0.65); }
.tile[data-val="1024"] { background: var(--t1024); color: var(--t1024-txt); font-size: clamp(12px,3.5vw,17px); box-shadow: 0 0 30px rgba(251,191,36,0.7); }
.tile[data-val="2048"] { background: var(--t2048); color: var(--t2048-txt); font-size: clamp(12px,3.5vw,17px); box-shadow: 0 0 36px rgba(245,158,11,0.85); animation: glow2048 1.5s ease-in-out infinite; }
.tile[data-val]        { background: var(--tsuper); color: var(--tsuper-txt); font-size: clamp(10px,3vw,14px); box-shadow: 0 0 40px rgba(255,255,255,0.8); }

@keyframes glow2048 {
  0%,100% { box-shadow: 0 0 36px rgba(245,158,11,0.85); }
  50%      { box-shadow: 0 0 56px rgba(245,158,11,1); }
}

/* re-apply specific tiles over the catch-all [data-val] */
.tile[data-val="2"]    { background: var(--t2)    !important; color: var(--t2-txt)    !important; }
.tile[data-val="4"]    { background: var(--t4)    !important; color: var(--t4-txt)    !important; }
.tile[data-val="8"]    { background: var(--t8)    !important; color: var(--t8-txt)    !important; }
.tile[data-val="16"]   { background: var(--t16)   !important; color: var(--t16-txt)   !important; }
.tile[data-val="32"]   { background: var(--t32)   !important; color: var(--t32-txt)   !important; }
.tile[data-val="64"]   { background: var(--t64)   !important; color: var(--t64-txt)   !important; }
.tile[data-val="128"]  { background: var(--t128)  !important; color: var(--t128-txt)  !important; }
.tile[data-val="256"]  { background: var(--t256)  !important; color: var(--t256-txt)  !important; }
.tile[data-val="512"]  { background: var(--t512)  !important; color: var(--t512-txt)  !important; }
.tile[data-val="1024"] { background: var(--t1024) !important; color: var(--t1024-txt) !important; }
.tile[data-val="2048"] { background: var(--t2048) !important; color: var(--t2048-txt) !important; }

/* ── HINT ROW ── */
.hint-row {
  display: flex;
  justify-content: space-between;
  position: relative;
  z-index: 1;
}

.hint {
  font-size: 11px;
  color: var(--text-muted);
}

/* ── OVERLAYS ── */
.overlay {
  position: absolute;
  inset: 0;
  background: rgba(8,5,15,0.82);
  -webkit-backdrop-filter: blur(5px);
  backdrop-filter: blur(5px);
  border-radius: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
  padding: 20px;
}

.overlay.hidden { display: none; }

.overlay-modal {
  text-align: center;
  animation: pop 0.4s cubic-bezier(.34,1.56,.64,1);
}

@keyframes pop {
  0%   { transform: scale(0.7); opacity: 0; }
  100% { transform: scale(1);   opacity: 1; }
}

.overlay-emoji { font-size: 44px; margin-bottom: 10px; }

.overlay-modal h2 {
  font-family: 'Space Grotesk', sans-serif;
  font-size: 24px;
  font-weight: 700;
  color: var(--purple-bright);
  margin-bottom: 8px;
}

.overlay-modal p {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 18px;
}

.overlay-modal p span {
  color: var(--purple-bright);
  font-weight: 700;
  font-family: 'Space Grotesk', sans-serif;
}

.overlay-btns { display: flex; gap: 10px; justify-content: center; }

.primary-btn {
  background: linear-gradient(135deg, var(--purple), var(--purple-dim));
  border: none;
  color: white;
  font-weight: 700;
  font-size: 13px;
  padding: 10px 22px;
  border-radius: 12px;
  cursor: pointer;
  box-shadow: 0 0 20px -4px var(--violet-glow);
  transition: transform 0.15s, box-shadow 0.2s;
}

.primary-btn:hover { transform: translateY(-2px); box-shadow: 0 0 26px -2px var(--violet-glow); }
.primary-btn:active { transform: scale(0.97); }

.secondary-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 13px;
  padding: 10px 22px;
  border-radius: 12px;
  cursor: pointer;
  transition: all 0.2s;
}

.secondary-btn:hover { border-color: var(--purple); color: var(--text-main); }

@media (max-width: 380px) {
  h1 { font-size: 30px; }
  .score-value { font-size: 16px; }
}