body {
  margin: 0;
  background: #0d1117;
  color: #ffffff;
  font-family: 'Segoe UI', sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.equation-card {
  background: #161b22;
  border-radius: 1rem;
  padding: 2rem;
  box-shadow: 0 0 25px rgba(0, 255, 255, 0.2);
  text-align: center;
  transition: box-shadow 0.3s ease;
  width: 90%;
  max-width: 400px;
  height: 200px;
  justify-content: space-around;
}

#equation {
  font-size: 2rem;
  margin-bottom: 1rem;
}

input[type="text"] {
  font-size: 1.2rem;
  padding: 0.5rem 1rem;
  width: 80%;
  max-width: 200px;
  margin-bottom: 1rem;
  border-radius: 0.5rem;
  border: none;
  outline: none;
  appearance: none;
  background-color: #0d1117;
  color: #fff;
  box-sizing: border-box;
}

input[type="text"]::-webkit-inner-spin-button,
input[type="text"]::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.equation-card input[type="text"] {
  font-size: 1.2rem;
  padding: 0.5rem 1rem;
  width: 80%;
  max-width: 200px;
  margin-bottom: 1rem;
  border-radius: 0.5rem;
  border: none;
  outline: none;
  appearance: none;
  background-color: #0d1117;
  color: #fff;
  box-sizing: border-box;
}
#feedback {
  font-size: 1rem;
  margin-top: 0.5rem;
}

button {
  margin-top: 1.5rem;
  padding: 0.5rem 1.2rem;
  font-size: 1rem;
  border: none;
  border-radius: 0.5rem;
  background-color: #00bcd4;
  color: white;
  cursor: pointer;
}

.correct {
  box-shadow: 0 0 25px rgba(0, 255, 0, 0.5);
}

.incorrect {
  box-shadow: 0 0 25px rgba(255, 0, 0, 0.5);
}