body {
    margin: 0;
    font-family: 'Quicksand', sans-serif;
    background: linear-gradient(to right, #141e30, #243b55);
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    color: #fff;
  }
  
  .hidden {
    display: none !important;
  }
  
  .intro, .calculator {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(15px);
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 0 25px rgba(0, 0, 0, 0.3);
    text-align: center;
    animation: fadeIn 1s ease-in-out;
  }
  
  .intro input {
    padding: 10px;
    margin: 10px;
    width: 80%;
    border: none;
    border-radius: 10px;
    font-size: 16px;
  }
  
  .intro button {
    padding: 10px 20px;
    font-size: 16px;
    border: none;
    border-radius: 10px;
    background-color: #00ffe7;
    color: #000;
    cursor: pointer;
  }
  
  #greetUser {
    margin-bottom: 15px;
  }
  
  .calculator {
    width: 300px;
    transition: width 0.4s ease-in-out;
  }
  
  .calculator.scientific-mode {
    width: 500px;
  }
  
  .calculator input {
    width: 100%;
    height: 50px;
    font-size: 22px;
    text-align: right;
    margin-bottom: 20px;
    padding: 10px;
    border-radius: 10px;
    border: none;
    color: #00ffe7;
    background-color: rgba(0, 0, 0, 0.6);
  }
  
  .buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
    margin-bottom: 10px;
  }
  
  #scientificButtons {
    grid-template-columns: repeat(4, 1fr);
  }
  
  button {
    height: 50px;
    font-size: 18px;
    border: none;
    border-radius: 12px;
    background: rgba(255, 255, 255, 0.2);
    color: white;
    transition: all 0.2s ease;
    cursor: pointer;
  }
  
  button:hover {
    background-color: #00ffe7;
    color: #000;
    transform: scale(1.05);
  }
  
  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
  }