body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
  }
  
  .container {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    max-width: 500px;
    width: 100%;
    text-align: center;
  }
  
  h1 {
    color: #333;
  }
  
  .instructions {
    font-size: 14px;
    color: #555;
    margin-bottom: 10px;
  }
  
  .calculator {
    display: flex;
    flex-direction: column;
    gap: 10px;
  }
  
  .unit-switch {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 20px;
  }
  
  .unit-switch button {
    padding: 10px 20px;
    border-radius: 5px;
    border: none;
    background-color: #007BFF;
    color: white;
    cursor: pointer;
  }
  
  .unit-switch button.active {
    background-color: #0056b3;
  }
  
  label {
    font-weight: bold;
  }
  
  input, select, button {
    padding: 10px;
    border-radius: 5px;
    border: 1px solid #ccc;
    font-size: 16px;
  }
  
  button {
    background-color: #007BFF;
    color: white;
    cursor: pointer;
  }
  
  button:hover {
    background-color: #0056b3;
  }
  
  .hidden {
    display: none;
  }
  
  .result {
    margin-top: 20px;
  }
  
  .bmi-scale {
    margin: 20px 0;
  }
  
  .scale-bar {
    display: flex;
    height: 10px;
    background: linear-gradient(to right, #4CAF50, #FFC107, #FF5722, #F44336);
    border-radius: 5px;
  }
  
  .scale-labels, .scale-categories {
    display: flex;
    justify-content: space-between;
    font-size: 12px;
    color: #555;
    margin-top: 5px;
  }
  
  #bmiResult, #bmiCategory, #healthyWeightRange, #weightToLose, #bmiPrime, #ponderalIndex {
    color: #007BFF;
    font-size: 18px;
    font-weight: bold;
  }