style.css

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@500&display=swap');
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
    outline: none;
}
body{
    display: flex;
    height: 100vh;
    justify-content: center;
    padding: 10px;
    align-items: center;
    background: linear-gradient(135deg, #71b7e6, #9b59b6);
}
.container{
    max-width: 800px;
    width: 493px;
    background: #fff;
    padding: 25px 30px;
    border-radius: 5px;
    justify-content: center;
    align-items: center;
    margin-right: 5px;
}
.form-control {
    text-align: center;
    outline: none;
    border: 1px solid lightblue;
    padding: 3px;
    border-radius: 100px;
    font-size: 20px;
    margin: 5px;
    max-width: 100%;
    width: 100%;
}
.form-control::-webkit-inner-spin-button{
    -webkit-appearance: none;
    margin: 0;
}
.form-control:focus {
    border: 1px solid dodgerblue;
    box-shadow: rgba(0, 0, 0, 0.16) 0px 1px 4px;
}
.select {
    outline: none;
    border: 1px solid pink;
    font-size: 15px;
    border-radius: 50px;
    text-align: center;
    justify-content: center;
    padding: 10px;
    width: auto;
}
.btn {
    background-color: rgb(106, 175, 255);
    box-shadow: rgba(0, 0, 0, 0.16) 0px 1px 4px;
    border: 0px solid grey;
    border-radius: 50px;
    margin: 5px;
    max-width: 100%;
    width: 100%;
    padding: 10px;
    font-size: 15px;
}
.answer-div{
    font-size: 35px;
    text-align: center;
}
#answer{
    color: rgb(55, 55, 255);
}
.cont{
    display: flex;
}