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

:root {
  --bg: #0a0a0f;
  --surface: #14141f;
  --border: #2a2a3a;
  --pink: #ff2d78;
  --cyan: #00e5ff;
  --gold: #ffd700;
  --text: #e8e8f0;
  --text-dim: #8888aa;
  --cell-size: min(80px, calc((100vw - 60px) / 4));
  --gap: 8px;
}

body {
  font-family: 'Segoe UI', 'Hiragino Sans', 'Noto Sans JP', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  user-select: none;
  -webkit-user-select: none;
  overflow-x: hidden;
}

/* ===== Header ===== */
.header {
  text-align: center;
  padding: 16px 8px 8px;
  width: 100%;
  max-width: 440px;
}
.header h1 {
  font-size: 1.6rem;
  background: linear-gradient(135deg, var(--pink), var(--cyan));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 2px;
}
.header .subtitle {
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-top: 2px;
}

/* ===== Score Bar ===== */
.score-bar {
  display: flex;
  gap: 12px;
  justify-content: center;
  margin: 8px 0;
  width: 100%;
  max-width: 440px;
}
.score-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 16px;
  text-align: center;
  min-width: 90px;
}
.score-box .label {
  font-size: 0.65rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.score-box .value {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--cyan);
}
.score-box .value.best {
  color: var(--gold);
}

/* ===== Controls ===== */
.controls {
  display: flex;
  gap: 8px;
  margin: 6px 0;
  flex-wrap: wrap;
  justify-content: center;
  max-width: 440px;
}
.btn {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: 8px 14px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  gap: 4px;
}
.btn:hover { border-color: var(--pink); background: #1a1a2e; }
.btn:active { transform: scale(0.95); }
.btn.primary {
  background: linear-gradient(135deg, var(--pink), #cc1155);
  border-color: var(--pink);
  font-weight: 600;
}
.btn.primary:hover { filter: brightness(1.15); }
.btn .undo-count {
  background: var(--cyan);
  color: #000;
  border-radius: 50%;
  width: 18px;
  height: 18px;
  font-size: 0.65rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

/* ===== Grid ===== */
.grid-wrapper {
  position: relative;
  margin: 8px 0;
}
.grid {
  display: grid;
  grid-template-columns: repeat(4, var(--cell-size));
  grid-template-rows: repeat(4, var(--cell-size));
  gap: var(--gap);
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: 12px;
  padding: var(--gap);
  position: relative;
}

/* Empty cells */
.cell-bg {
  width: var(--cell-size);
  height: var(--cell-size);
  background: #1a1a28;
  border-radius: 8px;
}

/* ===== Tiles ===== */
.tile {
  position: absolute;
  width: var(--cell-size);
  height: var(--cell-size);
  border-radius: 8px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  transition: top 0.12s ease, left 0.12s ease;
  z-index: 2;
}
.tile img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 6px;
}
.tile .rarity-badge {
  position: absolute;
  bottom: 2px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.55rem;
  font-weight: 800;
  padding: 1px 6px;
  border-radius: 4px;
  letter-spacing: 1px;
  text-shadow: 0 1px 2px rgba(0,0,0,0.8);
  white-space: nowrap;
}

/* Rarity colors */
.rarity-N    .rarity-badge { background: #555; color: #ccc; }
.rarity-Nplus .rarity-badge { background: #666; color: #ddd; }
.rarity-R    .rarity-badge { background: #2255cc; color: #fff; }
.rarity-Rplus .rarity-badge { background: #3366ee; color: #fff; }
.rarity-SR   .rarity-badge { background: #9922cc; color: #fff; }
.rarity-SRplus .rarity-badge { background: #bb33ee; color: #fff; }
.rarity-SSR  .rarity-badge { background: #cc8800; color: #fff; }
.rarity-SSRplus .rarity-badge { background: #ee9900; color: #fff; }
.rarity-UR   .rarity-badge { background: linear-gradient(135deg, #ff2d78, #ff6b9d); color: #fff; }
.rarity-LEGEND .rarity-badge { background: linear-gradient(135deg, #ffd700, #ffaa00); color: #000; }
.rarity-GOD  .rarity-badge { background: linear-gradient(135deg, #ffd700, #ff2d78, #00e5ff); color: #fff; }

/* Tile borders by rarity */
.rarity-N, .rarity-Nplus { border: 2px solid #555; }
.rarity-R, .rarity-Rplus { border: 2px solid #2255cc; }
.rarity-SR, .rarity-SRplus { border: 2px solid #9922cc; }
.rarity-SSR, .rarity-SSRplus { border: 2px solid #cc8800; }
.rarity-UR { border: 2px solid var(--pink); box-shadow: 0 0 12px rgba(255,45,120,0.4); }
.rarity-LEGEND { border: 2px solid var(--gold); box-shadow: 0 0 16px rgba(255,215,0,0.5); }
.rarity-GOD {
  border: 2px solid var(--gold);
  box-shadow: 0 0 20px rgba(255,215,0,0.6), 0 0 40px rgba(255,45,120,0.3);
}
.rarity-GOD img { filter: sepia(0.3) saturate(1.8) brightness(1.1) hue-rotate(-10deg); }
.rarity-GOD::before {
  content: '';
  position: absolute;
  inset: -2px;
  border-radius: 8px;
  background: linear-gradient(135deg, #ffd700, #ff2d78, #00e5ff, #ffd700);
  background-size: 300% 300%;
  animation: godBorder 2s ease infinite;
  z-index: -1;
}
@keyframes godBorder {
  0%, 100% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
}

/* Animations */
.tile-new {
  animation: tileAppear 0.2s ease;
}
@keyframes tileAppear {
  0% { transform: scale(0); opacity: 0; }
  100% { transform: scale(1); opacity: 1; }
}
.tile-merge {
  animation: tileMerge 0.25s ease;
}
@keyframes tileMerge {
  0% { transform: scale(1); }
  40% { transform: scale(1.25); }
  100% { transform: scale(1); }
}

/* ===== Overlay ===== */
.overlay {
  position: absolute;
  inset: 0;
  background: rgba(10, 10, 15, 0.85);
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 10;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
}
.overlay.active {
  opacity: 1;
  pointer-events: all;
}
.overlay h2 {
  font-size: 1.5rem;
  margin-bottom: 8px;
}
.overlay .final-score {
  font-size: 1.1rem;
  color: var(--cyan);
  margin-bottom: 12px;
}
.overlay .btn { margin: 4px; }

/* ===== Patreon CTA ===== */
.patreon-cta {
  margin: 12px 0;
  text-align: center;
}
.patreon-cta a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: linear-gradient(135deg, #ff424d, #ff2d78);
  color: #fff;
  text-decoration: none;
  padding: 10px 20px;
  border-radius: 24px;
  font-weight: 700;
  font-size: 0.85rem;
  transition: all 0.2s;
  box-shadow: 0 4px 15px rgba(255,45,120,0.3);
}
.patreon-cta a:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(255,45,120,0.4); }
.patreon-cta .cta-sub {
  font-size: 0.7rem;
  color: var(--text-dim);
  margin-top: 4px;
}

/* ===== Footer ===== */
.footer {
  text-align: center;
  padding: 12px;
  color: var(--text-dim);
  font-size: 0.7rem;
  max-width: 440px;
}
.footer a { color: var(--pink); text-decoration: none; }
.footer a:hover { text-decoration: underline; }

/* ===== How to Play ===== */
.how-to-play {
  max-width: 440px;
  width: 100%;
  padding: 0 16px;
  margin-bottom: 16px;
}
.how-to-play details {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 8px 12px;
}
.how-to-play summary {
  cursor: pointer;
  font-size: 0.8rem;
  color: var(--cyan);
  font-weight: 600;
}
.how-to-play .content {
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-top: 8px;
  line-height: 1.6;
}

/* ===== Responsive ===== */
@media (max-width: 400px) {
  :root { --cell-size: calc((100vw - 56px) / 4); --gap: 6px; }
  .header h1 { font-size: 1.3rem; }
  .score-box { padding: 4px 10px; min-width: 70px; }
  .score-box .value { font-size: 1.1rem; }
}
@media (min-width: 500px) {
  :root { --cell-size: 90px; }
}

/* Level-up notification */
.level-up-toast {
  position: fixed;
  top: 20%;
  left: 50%;
  transform: translateX(-50%) scale(0);
  background: linear-gradient(135deg, rgba(255,215,0,0.95), rgba(255,45,120,0.95));
  color: #fff;
  padding: 12px 24px;
  border-radius: 12px;
  font-size: 1.2rem;
  font-weight: 800;
  z-index: 100;
  pointer-events: none;
  text-align: center;
  box-shadow: 0 0 30px rgba(255,215,0,0.5);
  animation: toastPop 1.5s ease forwards;
}
@keyframes toastPop {
  0% { transform: translateX(-50%) scale(0); opacity: 0; }
  15% { transform: translateX(-50%) scale(1.2); opacity: 1; }
  25% { transform: translateX(-50%) scale(1); }
  75% { transform: translateX(-50%) scale(1); opacity: 1; }
  100% { transform: translateX(-50%) translateY(-40px) scale(0.8); opacity: 0; }
}