body {
    font-family: Arial, sans-serif;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f0f0f0;
    margin: 0;
}

header {
    text-align: center;
    margin-bottom: 20px;
}

.calculator {
    background-color: #fff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    width: 300px;
    text-align: center;
}

.input-group {
    margin-bottom: 15px;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.input-group label {
    margin-bottom: 5px;
    font-weight: bold;
}

.input-group input {
    width: 100%;
    padding: 10px;
    border: 1px solid #ccc;
    border-radius: 5px;
    font-size: 16px;
    box-sizing: border-box;
}

#calculate {
    padding: 10px 20px;
    font-size: 18px;
    color: white;
    background-color: #007bff;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s ease;
    margin-top: 10px;
}

#calculate:hover {
    background-color: #0056b3;
}

#result {
    margin-top: 20px;
    font-size: 18px;
    font-weight: bold;
    padding: 10px;
    border-radius: 5px;
}

.underweight {
    background-color: #bee5eb; /* Light Blue */
}

.normal {
    background-color: #c3e6cb; /* Light Green */
}

.overweight {
    background-color: #ffeeba; /* Light Yellow */
}

.obese {
    background-color: #f5c6cb; /* Light Red */
}