body {
    background-image: url("image.jpg");
    background-color: #BBDEFB;
    background-size: cover;      
    background-repeat: no-repeat; 
    background-position: center;  
    background-attachment: fixed; 
}

.container {
    width: 400px;
    /* center the div */
    margin: 0 auto;
}

.top-part {
    background-color: #1976D2;
    font-size: 50px; 
    color: #fff;
    font-family: arial;
    text-align: center;
    padding: 30px 0;
}

.bottom-part {
    background-color: #fbfbfb;
    padding: 25px;
    font-family: Arial, sans-serif;
    box-sizing: border-box;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    font-size: 18px;
    margin-bottom: 8px;
    color: #222;
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 10px;
    font-size: 15px;
    border: 1px solid #b0b0b0;
    box-sizing: border-box;
    outline: none;
    background-color: #fff;
}

.form-group input::placeholder {
    color: #999;
}

.btn {
    width: 100%;
    padding: 12px;
    font-size: 16px;
    border: none;
    cursor: pointer;
    margin-bottom: 15px;
    box-sizing: border-box;
    display: block;
}

.btn-calculate {
    background-color: #ff5722;
    color: #ffffff;
}

.btn-reset {
    background-color: #bbdefb;
    color: #222;
    border: 1px solid #64b5f6;
    margin-bottom: 0;
}