* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: Arial, sans-serif;

  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
  animation: backgroundAnimation 10s infinite alternate;
}

@keyframes backgroundAnimation {
  0% { background-color: #f4f4f4; }
  50% { background-color: #0d1b1d; }
  100% { background-color: #f4f4f4; }
}

.mode-selection {
  text-align: center;
  padding: 20px;
}
.mode-selection h1 {
  color: #2575fc;
  margin-bottom: 10px;
}
.mode-selection p {
  font-size: 18px;
  margin-bottom: 20px;
}
.mode-btn {
  background: #2575fc;
  color: #fff;
  border: none;
  padding: 10px 20px;
  margin: 5px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 16px;
  transition: background 0.3s;
}
.mode-btn:hover {
  background: #6a11cb;
}

.game-container {
  background: #fff;
  padding: 20px;
  border: 2px solid #2575fc;
  border-radius: 8px;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  text-align: center;
  width: 90%;
  max-width: 400px;
  margin-bottom: 20px;
}
.game-container h1 {
  color: #2575fc;
  margin-bottom: 10px;
}
#message {
  font-size: 18px;
  margin-bottom: 10px;
}

.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 5px;
  margin: 20px 0;
}
.cell {
  background: #e9e9e9;
  border: 2px solid #ccc;
  height: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 48px;
  cursor: pointer;
  transition: background 0.3s, transform 0.3s;
}
.cell:hover {
  background: #d1e0ff;
  transform: scale(1.05);
}

#resetBtn {
  background: #2575fc;
  color: #fff;
  border: none;
  padding: 10px 20px;
  font-size: 16px;
  border-radius: 4px;
  cursor: pointer;
  transition: background 0.3s;
}
#resetBtn:hover {
  background: #6a11cb;
}


.footer {
  text-align: center;
  padding: 15px 0;
  width: 100%;
  position: fixed;
  bottom: 0;
  animation: footerAnimation 5s infinite alternate;
}
@keyframes footerAnimation {
  0% { background-color: #2575fc; }
  50% { background-color: #6a11cb; }
  100% { background-color: #2575fc; }
}


@media (max-width: 500px) {
  .cell {
    height: 80px;
    font-size: 36px;
  }
}

@keyframes celebrate {
  0% { transform: scale(1); }
  50% { transform: scale(1.2); }
  100% { transform: scale(1); }
}
.celebrate {
  animation: celebrate 1s ease-in-out;
}