body {
  font-family: Arial, sans-serif;
  background: #0f172a;
  color: white;
  padding: 20px;
  text-align: center;
  margin: 0;
}

.box {
  background: white;
  color: black;
  padding: 20px;
  border-radius: 15px;
  margin: 20px auto;
  max-width: 400px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.3);
}

input {
  width: 90%;
  padding: 15px;
  border-radius: 10px;
  border: 2px solid #16a34a;
  font-size: 16px;
  margin-top: 10px;
}

button {
  background: #16a34a;
  color: white;
  padding: 15px 30px;
  border: none;
  border-radius: 10px;
  font-size: 18px;
  margin-top: 15px;
  width: 95%;
  cursor: pointer;
}

button:hover {
  background: #15803d;
}

#answer {
  background: #f0fdf4;
  padding: 15px;
  border-radius: 10px;
  margin-top: 20px;
  text-align: left;
  color: #14532d;
  display: none;
  border: 1px solid #16a34a;
}

h1 {
  color: #22c55e;
}