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

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  background: linear-gradient(135deg, #f6f8fa 0%, #e9ecef 100%);
  color: #333;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

.container {
  max-width: 600px;
  width: 100%;
  text-align: center;
}

h1 {
  color: #0066cc;
  margin-bottom: 20px;
  font-size: 2.5rem;
  text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
}

.status {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
  padding: 10px;
  background-color: white;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.game-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin-bottom: 20px;
}

.column-selector {
  display: flex;
  gap: 6px;
  margin-bottom: 8px;
}

.colbtn {
  width: 56px;
  padding: 6px;
  background: #fff;
  border: 2px solid #0066cc;
  border-radius: 6px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s;
}

.colbtn:hover {
  background: #e6f0ff;
  transform: translateY(-2px);
}

.colbtn:disabled {
  background: #f0f0f0;
  border-color: #ccc;
  cursor: not-allowed;
  transform: none;
}

.board {
  display: grid;
  gap: 6px;
  background: #0066cc;
  padding: 8px;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.cell {
  width: 56px;
  height: 56px;
  background: #e6f0ff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 24px;
  transition: background-color 0.3s;
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.1);
}

.cell.empty {
  background: #f0f6ff;
}

.cell.player-x {
  background: #ff5252;
  color: white;
}

.cell.player-o {
  background: #ffeb3b;
  color: #333;
}

.controls {
  margin-top: 20px;
}

.btn {
  padding: 12px 24px;
  border-radius: 6px;
  border: none;
  background: #0066cc;
  color: white;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

.btn:hover {
  background: #0052a3;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

.btn:active {
  transform: translateY(0);
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

/* Animation for dropping pieces */
@keyframes drop {
  0% {
    transform: translateY(-300px);
    opacity: 0;
  }
  100% {
    transform: translateY(0);
    opacity: 1;
  }
}

.cell:not(.empty) {
  animation: drop 0.3s ease-out;
}

/* Responsive design */
@media (max-width: 600px) {
  .cell, .colbtn {
    width: 40px;
    height: 40px;
    font-size: 18px;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  .status {
    font-size: 1rem;
  }
}