body {
  font-family: sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  overflow: hidden;
}

.background {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1;
  background: radial-gradient(circle at center, #1a0f30 0%, #0a0618 100%);
}

.container {
  background-color: #333;
  color: #eee;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.5);
  text-align: center;
  border: 2px solid #555;
}

h1 {
  color: #fdd835;
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.7);
}

#game-area {
  margin-top: 25px;
}

#problem {
  font-size: 28px;
  color: #ffeb3b;
  margin-bottom: 15px;
  font-weight: 600;
}

#answer {
  padding: 10px;
  font-size: 18px;
  border-radius: 6px;
  border: 2px solid #ffca28;
  background-color: #444;
  color: #eee;
  width: 120px;
  text-align: center;
  margin-bottom: 15px;
}

#answer:focus {
  outline: none;
  border-color: #ffc107;
  box-shadow: 0 0 5px rgba(255, 193, 7, 0.5);
}

#submit {
  padding: 12px 24px;
  font-size: 18px;
  background-color: #fbc02d;
  color: #222;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  margin-left: 15px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
  transition: background-color 0.3s ease;
}

#submit:hover {
  background-color: #f9a825;
}

#submit:active {
  transform: translateY(1px);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

#feedback {
  margin-top: 15px;
  font-weight: bold;
  font-size: 20px;
}

#score {
  margin-top: 15px;
  font-size: 18px;
  color: #ffee58;
}

#challenge {
  margin-top: 20px;
  font-size: 20px;
  color: #fff;
}

#challenge-result {
  margin-top: 10px;
  font-size: 18px;
  font-weight: bold;
}

#restart-button {
  padding: 12px 24px;
  font-size: 18px;
  background-color: #4caf50;
  color: #fff;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  margin-top: 20px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
  transition: background-color 0.3s ease;
}

#restart-button:hover {
  background-color: #43a047;
}

#restart-button:active {
  transform: translateY(1px);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.5);
}

.answer-container {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-bottom: 15px;
}