body {
    background-color: rgba(199, 46, 95, 0.29);
}

.calculator {
    max-width: 320px;
    background: #fff;
    margin: 12% auto;
    min-height: 320px;
    border-radius: 5px;
    -webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
    box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
}

.display {
    padding-top: 6px;

}

.result {
    margin-left: 5px;
    display: block;
    width: 88%;
    height: 22px;
    padding: 6px 12px;
    font-size: 14px;
    line-height: 1.42857143;
    color: #000;
    background-color: #fff;
    border: 1px solid #ccc;
    border-radius: 4px;
    -webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
     box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
    -webkit-transition: border-color ease-in-out .15s,-webkit-box-shadow ease-in-out .15s;
    -o-transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
    transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
}

.keys {
    margin-top: 5px;
}

.column {
    display: inline-block;
    float: left;
    width: 23%;
    margin-left: 5px;
    color: #fff;
    background-color: #c30376;
}

.key-btn {
    margin-bottom: 5px;
    padding: 18px 0;
    font-size: 18px;
    font-weight: 400;
    line-height: 1.42857143;
    text-align: center;
    white-space: nowrap;
    vertical-align: middle;
    cursor: pointer;
    border: 1px solid transparent;
    border-radius: 4px;
}

.key-btn:hover,
.key-btn:active:hover {
    color: #fff;
    background-color: rgba(195, 3, 118, 0.76);
    border-color: rgba(195, 3, 118, 0.76);
}