body {
  font-family: Arial, sans-serif;
  background: #f4f4f4;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.quiz-container {
  background: white;
  padding: 20px;
  width: 400px;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}

h1 {
  text-align: center;
}

#options button {
  display: block;
  width: 100%;
  margin: 8px 0;
  padding: 10px;
  cursor: pointer;
}

.correct {
  background-color: green;
  color: white;
}

.wrong {
  background-color: #f44336;
  color: white;
}

.hidden {
  display: none;
}

#next-btn, #explain-btn {
  margin-top: 10px;
  width: 100%;
  padding: 10px;
}