body {
    background-color: #111;
    color:#bbb;
}
.grey {
    background-color: #222;
    width: 320px;
    height: 550px;
    border-radius: 15px;
}
.screen {
    margin-top: 50px;
    margin-bottom: 50px;
    background-color: #334;
    height: 50px;
    border-radius: 15px;
    font-size: 40px;
    line-height: 50px;
    text-align: right;
}
.col-xs-3 {
    height:50px;
    width:50px;
    background-color: #233;
    border: 2px solid #ca3;
    margin:8px;
    border-radius: 15px;
    line-height: 45px;
    font-size: 30px;
    text-align: center;
}
.col-xs-3:hover, .col-xs-6:hover {
    background-color: #344;
    cursor:pointer;
}
.col-xs-6:active, .col-xs-3:active {
    transform: translateY(1px);
    border-color: #fa3;
}
button:focus{ outline:0;}
.col-xs-6 {
    height:50px;
    background-color: #233;
    border: 2px solid #ca3;
    width:116px;
    margin:8px;
    border-radius: 15px;
    line-height: 45px;
    font-size: 30px;
    text-align: center;
}
.row-margin {
    margin-right: 20px;
}