style.css

html {
    background-color: #66ff33;
    margin: 0px 0px;
    -webkit-user-select: none;
}
#wrapper {
    width: 100%;
    height: 100%;
    align-self: center;
    text-align: center;
    vertical-align: bottom;
    margin: 0px 0px;
}
#wrapper.unselectable {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}
#warning-message {
    width: 100%;
    height: 100%;
    display: none;
    text-align: center;
    vertical-align: middle;
    margin: 0px 0px;
    color: white;
    font-family: fantasy;
    font-style: italic;
}
#warning-message.unselectable {
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

@media only screen and (orientation:portrait){
    #wrapper {
      display:none;
    }
    #warning-message {
      display:block;
    }
}
@media only screen and (orientation:landscape){
    #warning-message {
      display:none;
    }
}
button {
    background-color: transparent;
    background-repeat: no-repeat;
    background-position: center;
    background-size: contain;
    border: 0;
    width: 20%;
    height: 25%;
    vertical-align: bottom;
    position: absolute;
}
button:hover, button:active, button:focus {
    border: 0;
    outline: none;
}
.button {
    background-color: #008CBA;
    border: 2px solid #008CBA;
    color: white;
    padding: 2%;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 4em;
    margin: 5%;
    cursor: pointer;
    border-radius: 20px;
    -webkit-transition-duration: 0.4s;
    transition-duration: 0.4s;
}
.button:hover {
    box-shadow: 0 12px 16px 0 rgba(0,0,0,0.24), 0 17px 50px 0 rgba(0,0,0,0.19);
}
#restart {
    background-image: url(img/restart.png);
    right: 15%;
    top: 2%;
}
#shutdown {
    background-image: url(img/shutdown.png);
    right: 0;
    top: 2%;
}
#up {
    background-image: url(img/up.png);
    left: 0;
    bottom: 30%;
}
#down {
    background-image: url(img/down.png);
    bottom: 0;
    left: 0;
}
#left {
    background-image: url(img/left.png);
    bottom: 0;
    right: 20%;
}
#right {
    background-image: url(img/right.png);
    bottom: 0;
    right: 0;
}
#restart:active {
    background-image: url(img/pressed/restart.png);
}
#shutdown:active {
    background-image: url(img/pressed/shutdown.png);
}