/* ============================================================
   AI Tic-Tac-Toe -- Styles
   ============================================================ */

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

:root {
  --clr-bg: #0b0e17;
  --clr-surface: #141825;
  --clr-surface-hover: #1c2133;
  --clr-border: #252a3a;
  --clr-text: #e4e7f1;
  --clr-text-dim: #7a809a;
  --clr-accent: #6c63ff;
  --clr-accent-glow: rgba(108, 99, 255, 0.35);
  --clr-x: #f472b6;
  --clr-x-glow: rgba(244, 114, 182, 0.4);
  --clr-o: #38bdf8;
  --clr-o-glow: rgba(56, 189, 248, 0.4);
  --clr-draw: #facc15;
  --clr-win-line: #a78bfa;
  --radius: 16px;
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
  font-size: 16px;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--clr-bg);
  color: var(--clr-text);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  overflow: hidden;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Animated Background Canvas ---------- */
#bg-canvas {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}

/* ---------- Container ---------- */
.container {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 420px;
  padding: 24px 20px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

/* ---------- Header ---------- */
.header {
  text-align: center;
}

.title {
  font-size: 2rem;
  font-weight: 900;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 10px;
  justify-content: center;
}

.title-icon {
  font-size: 1.4rem;
  color: var(--clr-accent);
  animation: spin-slow 6s linear infinite;
}

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

.title-badge {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  background: linear-gradient(135deg, var(--clr-accent), #a78bfa);
  color: #fff;
  padding: 3px 8px;
  border-radius: 6px;
  vertical-align: middle;
}

.subtitle {
  color: var(--clr-text-dim);
  font-size: 0.85rem;
  margin-top: 4px;
}

/* ---------- Difficulty Bar ---------- */
.difficulty-bar {
  display: flex;
  gap: 6px;
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  padding: 4px;
}

.diff-btn {
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--clr-text-dim);
  background: transparent;
  border: none;
  padding: 6px 18px;
  border-radius: 8px;
  cursor: pointer;
  transition: var(--transition);
}

.diff-btn:hover {
  color: var(--clr-text);
  background: var(--clr-surface-hover);
}

.diff-btn.active {
  color: #fff;
  background: var(--clr-accent);
  box-shadow: 0 2px 12px var(--clr-accent-glow);
}

/* ---------- Scoreboard ---------- */
.scoreboard {
  display: flex;
  gap: 10px;
  width: 100%;
}

.score-card {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius);
  padding: 10px 8px;
  transition: var(--transition);
}

.score-card.you .score-value { color: var(--clr-x); }
.score-card.ai .score-value { color: var(--clr-o); }
.score-card.draw .score-value { color: var(--clr-draw); }

.score-label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--clr-text-dim);
}

.score-value {
  font-size: 1.6rem;
  font-weight: 900;
  line-height: 1;
  margin-top: 2px;
  transition: transform 0.3s ease;
}

.score-value.bump {
  animation: bump 0.4s ease;
}

@keyframes bump {
  0%   { transform: scale(1); }
  40%  { transform: scale(1.4); }
  100% { transform: scale(1); }
}

/* ---------- Status ---------- */
.status {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--clr-text-dim);
  text-align: center;
  min-height: 24px;
  transition: var(--transition);
}

.status.win-x {
  color: var(--clr-x);
  text-shadow: 0 0 20px var(--clr-x-glow);
}

.status.win-o {
  color: var(--clr-o);
  text-shadow: 0 0 20px var(--clr-o-glow);
}

.status.draw {
  color: var(--clr-draw);
}

/* ---------- Board ---------- */
.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  width: 312px;
  height: 312px;
  position: relative;
}

.cell {
  position: relative;
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.8rem;
  font-weight: 900;
  color: transparent;
  transition: background var(--transition), border-color var(--transition),
    transform 0.15s ease, box-shadow var(--transition);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  overflow: hidden;
}

.cell::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  opacity: 0;
  transition: opacity var(--transition);
}

.cell:not(.taken):hover {
  background: var(--clr-surface-hover);
  border-color: var(--clr-accent);
  transform: scale(1.04);
  box-shadow: 0 0 20px var(--clr-accent-glow);
}

.cell:not(.taken):active {
  transform: scale(0.96);
}

.cell.taken {
  cursor: default;
}

/* X Mark */
.cell.x {
  color: var(--clr-x);
  animation: place-mark 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.cell.x::before {
  background: radial-gradient(circle at center, var(--clr-x-glow), transparent 70%);
  opacity: 0.3;
}

/* O Mark */
.cell.o {
  color: var(--clr-o);
  animation: place-mark 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.cell.o::before {
  background: radial-gradient(circle at center, var(--clr-o-glow), transparent 70%);
  opacity: 0.3;
}

@keyframes place-mark {
  0%   { transform: scale(0); opacity: 0; }
  60%  { transform: scale(1.15); }
  100% { transform: scale(1); opacity: 1; }
}

/* Winning cells */
.cell.winner {
  animation: winner-pulse 1s ease infinite alternate;
  border-color: var(--clr-win-line) !important;
  z-index: 2;
}

.cell.winner.x {
  box-shadow: 0 0 24px var(--clr-x-glow), inset 0 0 20px var(--clr-x-glow);
}

.cell.winner.o {
  box-shadow: 0 0 24px var(--clr-o-glow), inset 0 0 20px var(--clr-o-glow);
}

@keyframes winner-pulse {
  0%   { transform: scale(1); }
  100% { transform: scale(1.06); }
}

/* Win Line SVG */
.win-line-svg {
  position: absolute;
  top: 0;
  left: 0;
  width: 312px;
  height: 312px;
  pointer-events: none;
  z-index: 3;
  display: none;
}

.win-line-svg line {
  stroke: var(--clr-win-line);
  stroke-width: 4;
  stroke-linecap: round;
  filter: drop-shadow(0 0 8px var(--clr-accent-glow));
  stroke-dasharray: 500;
  stroke-dashoffset: 500;
  animation: draw-line 0.5s ease forwards;
}

.win-line-svg.visible {
  display: block;
}

@keyframes draw-line {
  to { stroke-dashoffset: 0; }
}

/* Board wrapper for positioning win line */
.board {
  position: relative;
}

/* ---------- Controls ---------- */
.controls {
  display: flex;
  gap: 10px;
}

.btn {
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  border: 1px solid var(--clr-border);
  background: var(--clr-surface);
  color: var(--clr-text);
  padding: 10px 20px;
  border-radius: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition);
}

.btn:hover {
  background: var(--clr-surface-hover);
  border-color: var(--clr-accent);
  box-shadow: 0 2px 16px var(--clr-accent-glow);
}

.btn:active {
  transform: scale(0.96);
}

.btn-sound {
  padding: 10px 14px;
}

/* ---------- Footer ---------- */
.footer {
  font-size: 0.72rem;
  color: var(--clr-text-dim);
  text-align: center;
  margin-top: 4px;
}

.heart {
  color: var(--clr-x);
  display: inline-block;
  animation: heartbeat 1.5s ease infinite;
}

@keyframes heartbeat {
  0%, 100% { transform: scale(1); }
  15%      { transform: scale(1.25); }
  30%      { transform: scale(1); }
  45%      { transform: scale(1.2); }
}

/* ---------- Particles (spawned by JS) ---------- */
.particle {
  position: fixed;
  border-radius: 50%;
  pointer-events: none;
  z-index: 10;
  animation: particle-fly 0.7s ease-out forwards;
}

@keyframes particle-fly {
  0%   { opacity: 1; transform: translate(0, 0) scale(1); }
  100% { opacity: 0; transform: translate(var(--dx), var(--dy)) scale(0); }
}

/* Confetti */
.confetti {
  position: fixed;
  width: 8px;
  height: 8px;
  pointer-events: none;
  z-index: 10;
  animation: confetti-fall 1.5s ease-out forwards;
}

@keyframes confetti-fall {
  0%   { opacity: 1; transform: translateY(0) rotate(0deg) scale(1); }
  100% { opacity: 0; transform: translateY(120px) rotate(720deg) scale(0.3); }
}

/* ---------- Responsive ---------- */
@media (max-width: 420px) {
  .container {
    padding: 16px 12px 12px;
    gap: 14px;
  }

  .title {
    font-size: 1.6rem;
  }

  .board {
    width: 280px;
    height: 280px;
  }

  .win-line-svg {
    width: 280px;
    height: 280px;
  }

  .cell {
    font-size: 2.2rem;
    border-radius: 12px;
  }
}

@media (max-height: 700px) {
  .container {
    gap: 10px;
    padding-top: 10px;
  }

  .scoreboard {
    gap: 6px;
  }

  .score-card {
    padding: 6px 4px;
  }
}