body {
  font-family: Arial, sans-serif;
  background: linear-gradient(135deg, #0077ff, #00c3ff);
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  color: white;
}

.container {
  text-align: center;
  background: rgba(0, 0, 0, 0.4);
  padding: 30px;
  border-radius: 20px;
  box-shadow: 0 0 15px rgba(0,0,0,0.5);
  width: 300px;
  animation: fadeIn 0.5s ease;
}

h1 {
  margin-bottom: 10px;
}

#pontuacao, #timer {
  font-size: 18px;
  margin: 5px 0;
}

#equacao {
  font-size: 28px;
  margin: 20px 0;
}

#opcoes button {
  background-color: #222;
  color: white;
  border: none;
  margin: 5px;
  padding: 10px 20px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 16px;
  transition: transform 0.2s, background 0.2s;
}

#opcoes button:hover {
  transform: scale(1.1);
}

.correta {
  background-color: #28a745 !important;
}

.errada {
  background-color: #dc3545 !important;
}

.hidden {
  display: none;
}

#gameover {
  margin-top: 20px;
}

#gameover button {
  background-color: #007bff;
  border: none;
  padding: 10px 15px;
  border-radius: 8px;
  cursor: pointer;
  color: white;
}

@keyframes fadeIn {
  from { opacity: 0; transform: scale(0.9); }
  to { opacity: 1; transform: scale(1); }
}