calculator.css

body{
    padding:0;
    margin:0;
    background:linear-gradient(to right, #00AAFF, #00FF6C);
}
.calc{
    width: 320px;
    height:520px;
    background-color: white;
    margin: 0 auto;
    top: 20px;
    poosition:relative;
    border-radius:5px;
}
#screen{
    width:75%;
    height:80px;
    margin-left: 36px;
    margin-top: 30px;
    pointer-events: none;
}
.operator,.number,.empty{
    width:50px;
    height:50px;
    margin:15px;
    float:left;
    border-radius:50%;
    border-width:0;
    font-weight: bold;
    font-size:15px;
}
button:nth-child(4){
    font-size: 20px;
    background-color: #20b2aa;
}
button:nth-child(8){
    font-size: 20px;
    background-color: #ffa500;
}
button:nth-child(12){
    font-size: 20px;
    background-color: #f08080;
}
button:nth-child(16){
    font-size: 20px;
    background-color: #7d93e0;
}
button:nth-child(20){
    font-size: 20px;
    background-color: #9477af;
}