style.css

body {
    margin: 0;
    box-sizing: border-box;
    font-family: "PT Sans", sans-serif;
    background-image: linear-gradient(to right, rgb(38, 27, 22), rgb(138, 15, 2));
}

.main-div {
    margin: 8% auto;
    width: 25%;
    border-radius: 20px;
    border: 0.1px solid white;
    overflow: hidden;
}

.heading {
    background-color: rgb(31, 3, 12);
    color: white;
    text-align: center;
    margin-top: 0;
    margin-bottom: 0;
    padding: 0.5rem 0;
}

.main-content {
    background-color: rgb(247, 247, 247);
    padding: 1rem 0.5rem;
}

.bill-ques {
    margin-top: 0;
    margin-bottom: 0;
    padding: 1rem 0.5rem;
}

#btn {
    border: none;
    background-color: rgb(173, 19, 58);
    padding: 0.7rem 0.4rem;
}

#btn:hover {
    background-color: rgb(76, 40, 39);
}

input {
    margin-bottom: 1rem;
}

.cal-btn {
    text-align: center;
}

#each {
    padding-left: 2rem;
    margin: 0;
}

@media screen and (max-width: 768px) {
    .main-div {
        margin: 0 auto;
        width: 60%;
        border-radius: 10px;
    }    
}