styling.css

* {
    font: bold 18px Arial, sans-serif;
}

#calculator {
    width: 340px;
    height: auto;
    margin: 125px auto;
    padding: 20px 10px 5px 40px;
    background: #1BF1E4;
    border-radius: 20px;
}


button.clear {
    margin-left: 0px;
    margin-right: 20px;
    width: 50px;
    font-size: 30px;
    line-height: 50px;
    height: 50px;
    background-color: red;
    color: white;
}

input {
    height: 55px;
    width: 240px;
    margin-bottom: 25px;
    text-align: right;
    background: #6469DC;
    border: solid 1px #5619b8;
    border-radius: 15px;
    font-size: 30px;
    line-height: 30px;
    color: white;
}

button {
    width: 50px;
    height: 50px;
    margin-right: 38px;
    margin-bottom: 34px;
    text-align: center;
    background: #1182EB;
    color: #000000;
    border: solid 1px #5619b8;
    border-radius: 80px;
    font-size: 30px;
    line-height: 35px;
}

button.operator {
    margin-right: 10px;
}