:root {
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --cell-bg: #334155;
  --cell-hover: #475569;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --color-x: #38bdf8;
  --color-o: #f43f5e;
  --color-win: #22c55e;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

.container {
  background-color: var(--card-bg);
  padding: 30px;
  border-radius: 16px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.4);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 20px;
  max-width: 420px;
  width: 100%;
}

h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.mode-select {
  display: flex;
  gap: 10px;
  width: 100%;
}

.mode-select button {
  flex: 1;
  background: var(--cell-bg);
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 8px 12px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s ease;
}

.mode-select button.active {
  background: var(--accent);
  color: white;
}

.status {
  font-size: 1.15rem;
  font-weight: 600;
  min-height: 28px;
}

.player-x {
  color: var(--color-x);
}

.player-o {
  color: var(--color-o);
}

.scoreboard {
  display: flex;
  justify-content: space-between;
  width: 100%;
  gap: 12px;
}

.score-card {
  flex: 1;
  background: var(--cell-bg);
  padding: 10px;
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.score-card .label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  font-weight: 600;
}

.score-card .score {
  font-size: 1.4rem;
  font-weight: 700;
}

.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  width: 100%;
  aspect-ratio: 1 / 1;
}

.cell {
  background-color: var(--cell-bg);
  border: none;
  border-radius: 12px;
  font-size: 3rem;
  font-weight: bold;
  cursor: pointer;
  display: flex;
  justify-content: center;
  align-items: center;
  transition: background-color 0.2s ease, transform 0.1s ease;
  user-select: none;
}

.cell:hover:not(:disabled) {
  background-color: var(--cell-hover);
  transform: scale(0.98);
}

.cell.x {
  color: var(--color-x);
}

.cell.o {
  color: var(--color-o);
}

.cell.winning {
  background-color: rgba(34, 197, 94, 0.25);
  border: 2px solid var(--color-win);
  animation: pulse 1s infinite alternate;
}

@keyframes pulse {
  from { transform: scale(1); }
  to { transform: scale(1.03); }
}

.controls {
  display: flex;
  gap: 10px;
  width: 100%;
}

.controls button {
  flex: 1;
  padding: 12px;
  border: none;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s ease;
}

#restart-btn {
  background-color: var(--accent);
  color: white;
}

#restart-btn:hover {
  background-color: var(--accent-hover);
}

#reset-all-btn {
  background-color: transparent;
  color: var(--text-muted);
  border: 1px solid var(--cell-bg);
}

#reset-all-btn:hover {
  background-color: var(--cell-bg);
  color: var(--text-main);
}