.compound-container {
  max-width: 420px;
  margin: 30px auto;
  background: linear-gradient(135deg, #f8f9fa, #e8ffe8);
  border: 2px solid #e63946;
  border-radius: 20px;
  padding: 20px;
  text-align: center;
  box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.compound-container h2 {
  color: #e63946;
  margin-bottom: 15px;
}

label {
  display: block;
  margin: 10px 0 5px;
  font-weight: 600;
  color: #333;
}

select, input {
  width: 85%;
  padding: 8px;
  margin-bottom: 12px;
  border: 1px solid #aaa;
  border-radius: 10px;
  text-align: center;
}

button {
  margin: 10px 5px;
  padding: 10px 18px;
  border: none;
  border-radius: 10px;
  color: #fff;
  font-weight: bold;
  cursor: pointer;
  transition: 0.3s;
}

#calculateBtn {
  background: #e63946;
}

#calculateBtn:hover {
  background: #d62828;
}

#resetBtn {
  background: #2a9d8f;
}

#resetBtn:hover {
  background: #21867a;
}

#result {
  margin-top: 15px;
  font-size: 18px;
  font-weight: bold;
  color: #222;
}