index.css

body {
    background-color: skyblue;
}

.main {
    background-color: pink;
    margin: 100px auto;
    width: 400px;
    height: 250px;
}

select {
    background-color: aquamarine;
    border-radius: 5px;
    width: 200px;
    height: 25px;
}

select:hover {
    background-color: rgb(103, 234, 190);
}

.from {
    margin: 10px 5px 5px 5px;
    width: 250px;
    height: 18px;
    padding: 7px;
}

.To {
    margin: 5px 5px 10px 5px;
    width: 250px;
    height: 18px;
    padding: 7px;
}

#currency-two {
    margin-left: 20px;
}

.amount {
    margin: 5px 5px 10px 5px;
    width: 250px;
    height: 20px;
    padding: 7px;
}

.cal {
    margin: 5px 5px 10px 5px;
    width: 250px;
    height: 18px;
    padding: 7px;
}

.btn {
    background-color: rgb(45, 162, 45);
    color: white;
    border-color: rgb(2, 101, 2);
    border-radius: 5px;
}

button:hover {
    background-color: rgb(6, 101, 6);
}

.ans {
    width: 271px;
    margin: 10px auto 5px auto;
}

#Ans-one {
    margin: 10px auto 10px auto;
    width: 370px;
    height: 25px;
    font-weight: bold;
    text-align: center;
}

#Ans-second {
    margin: 10px auto 10px auto;
    width: 370px;
    height: 25px;
    font-weight: bold;
    text-align: center;
}

input {
    border-radius: 5px;
}