.number,
.operator {
    height: 75px;
    width: 75px;
    font-size: 50px;
}

#numberDisplay {
    width: 308px;
    height: 71px;
    text-align: right;
    font-size: 40px;
    border: 2px solid black;
}

#equals {
    height: 75px;
    width: 75px;
    font-size: 50px;
}

#clearButton {
    height: 75px;
    font-size: 50px;
    width: 312px;
}