#calcBox{
    width:400px;
    height:600px;
    background-color: lightgray;
    top:20px;
    position:relative;
}
#screen{
    height: 120px;
}
#buttons{
    height:45 0px;
}
#display{
    text-align:right;
    height: 80px;
    margin:10px 20px;
    font-size:40px;
}
#calculate{
    text-align:right;
    height: 20px;
    margin:0 20px;
    padding-top:20px;
    font-size:20px;
}
.opp, .num, .empty{
    width:50px;
    height:50px;
    margin:15px;
    float: left;
    border-radius:50%;
    border-width:0;
    font-weight: bold;
    font-size:15px;
}
.num,.empty{
    background-color: lightgray;
}
.num,.opp{
    cursor:pointer;
}
.opp:active,.num:active{
    font-size:13px;
}
.opp:focus,.num:focus,.empty:focus{
    outline:0;
}
button:nth-child(1){
    font-size:20px;
    background-color:orange;
}
button:nth-child(2){
    font-size:20px;
    background-color:orange;
}
button:nth-child(3){
    font-size:20px;
    background-color:orange;
}
button:nth-child(4){
    font-size:20px;
    background-color:orange;
}
button:nth-child(5){
    font-size:20px;
    background-color:orange;
}
button:nth-child(6){
    font-size:20px;
    background-color:orange;
}
button:nth-child(10){
    font-size:20px;
    background-color:orange;
}
button:nth-child(11){
    font-size:20px;
    background-color:orange;
}
button:nth-child(15){
    font-size:20px;
    background-color:orange;
}
button:nth-child(16){
    font-size:20px;
    background-color:orange;
}
button:nth-child(20){
    font-size:20px;
    background-color:orange;
}
button:nth-child(21){
    font-size:20px;
    background-color:orange;
}
button:nth-child(25){
    font-size:20px;
    background-color:orange;
}
button:nth-child(27){
    font-size:20px;
    background-color:orange;
}
button:nth-child(28){
    font-size:20px;
    background-color:orange;
}
button:nth-child(29){
    font-size:20px;
    background-color:orange;
}