:root {
  --light-bg: #e4f0f5;
  --light-text: #333;
  --dark-bg: #1e1e1e;
  --dark-text: #eee;
  --cell-bg-light: #fefefe;
  --cell-bg-dark: #333;
  --accent-color: #ff685f;
  --outline-light: #cfd8dc;
  --outline-dark: #444;
  --line-light: #333;
  --line-dark: #eee;
  --font-family: "Inter", sans-serif;
  --transition: 0.3s ease;
}
[data-theme="light"] {
  --bg-color: var(--light-bg);
  --text-color: var(--light-text);
  --cell-bg: var(--cell-bg-light);
  --outline-color: var(--outline-light);
  --line-color: var(--line-light);
}
[data-theme="dark"] {
  --bg-color: var(--dark-bg);
  --text-color: var(--dark-text);
  --cell-bg: var(--cell-bg-dark);
  --outline-color: var(--outline-dark);
  --line-color: var(--line-dark);
}
html,
body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family);
  background: var(--bg-color);
  color: var(--text-color);
  transition: background var(--transition), color var(--transition);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
}
.title {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 600;
}
.controls {
  display: flex;
  align-items: center;
  gap: 1rem;
}
.select-container {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}
.select-container label {
  font-size: 0.8rem;
  margin-bottom: 0.2rem;
  opacity: 0.7;
}
.select-container select {
  font-size: 1rem;
  padding: 0.4rem 0.5rem;
  border-radius: 6px;
  border: 1px solid var(--outline-color);
  background: var(--cell-bg);
  color: var(--text-color);
  transition: background var(--transition), color var(--transition);
  outline: none;
  appearance: none;
}
.toggle-container {
  position: relative;
  width: 40px;
  height: 20px;
}
.toggle-container input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}
.toggle-label {
  position: absolute;
  cursor: pointer;
  background-color: var(--outline-color);
  border-radius: 20px;
  width: 40px;
  height: 20px;
  transition: background var(--transition);
}
.toggle-label:before {
  content: "";
  position: absolute;
  left: 2px;
  top: 2px;
  width: 16px;
  height: 16px;
  background: var(--bg-color);
  border-radius: 50%;
  transition: transform var(--transition), background var(--transition);
}
.toggle-container input:checked + .toggle-label {
  background: var(--accent-color);
}
.toggle-container input:checked + .toggle-label:before {
  transform: translateX(20px);
}
.scoreboard {
  display: flex;
  justify-content: center;
  gap: 2rem;
  padding: 0.5rem 0;
  font-size: 1.1rem;
}
.score {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.game-container {
  display: flex;
  justify-content: center;
  align-items: center;
  position: relative;
  flex: 1;
  padding: 1rem;
}
.board-container {
  position: relative;
  display: inline-block;
  background: var(--outline-color);
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
}
.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  width: 300px;
  height: 300px;
  background: var(--outline-color);
  border-radius: 12px;
}
.cell {
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 3rem;
  font-weight: bold;
  background: var(--cell-bg);
  border: 1px solid var(--outline-color);
  transition: transform var(--transition), background var(--transition);
  cursor: pointer;
}
.cell:hover {
  transform: scale(1.05);
  background: rgba(255, 255, 255, 0.1);
}
#winning-line {
  position: absolute;
  top: 0;
  left: 0;
  pointer-events: none;
  width: 100%;
  height: 100%;
}
.actions {
  display: flex;
  justify-content: center;
  margin: 1rem 0;
}
#reset-btn {
  background: var(--accent-color);
  color: #fff;
  border: none;
  padding: 0.6rem 1rem;
  font-size: 1rem;
  border-radius: 6px;
  cursor: pointer;
  transition: background var(--transition);
}
#reset-btn:hover {
  background: #e05d57;
}
.footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.9rem;
}
.footer a {
  color: var(--accent-color);
  text-decoration: none;
  transition: color var(--transition);
}
.footer a:hover {
  text-decoration: underline;
}
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: scale(0.5);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}
.cell.X::before,
.cell.O::before {
  animation: fadeIn 0.3s forwards ease-in-out;
  display: block;
}
@media (max-width: 500px) {
  .board {
    width: 90vw;
    height: 90vw;
  }
  .cell {
    font-size: 2rem;
  }
  .scoreboard {
    flex-direction: column;
    gap: 0.5rem;
  }
  .controls {
    flex-direction: column;
    gap: 0.5rem;
  }
  .select-container label {
    font-size: 0.7rem;
  }
}