body {  
    font-family: Arial, sans-serif;  
    margin: 20px;  
    padding: 0;  
}  
  
.calculator {  
    max-width: 600px;  
    margin: auto;  
    padding: 20px;  
    border: 1px solid #ccc;  
    border-radius: 8px;  
}  
  
.input-group {  
    margin-bottom: 15px;  
}  
  
.input-group label {  
    display: block;  
    margin-bottom: 5px;  
}  
  
.input-group input {  
    width: 100%;  
    padding: 8px;  
    box-sizing: border-box;  
}  
  
button {  
    padding: 10px 15px;  
    background-color: #007BFF;  
    color: white;  
    border: none;  
    border-radius: 5px;  
    cursor: pointer;  
    transition: background-color 0.3s;  
}  
  
button:hover {  
    background-color: #0056b3;  
}  
  
p {  
    margin-top: 10px;  
}