#panels {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
}
.key {
    height: 200px;
    width: 200px;
    border-radius: 8px;
    margin-right: 10px;
    margin-bottom: 10px;
    border: none;
    cursor: pointer;
    background-size: cover !important;
}
#settings {
    background: url("../img/norm_settings.png") no-repeat;
}
#settings:active {
    background: url("../img/inv_settings.png") no-repeat;
}
#beamer {
    background: url("../img/norm_beamer.png") no-repeat;
}
#beamer:active {
    background: url("../img/inv_beamer.png") no-repeat;
}
#music {
    background: url("../img/norm_music.png") no-repeat;
}
#music:active {
    background: url("../img/inv_music.png") no-repeat;
}
#bass {
    background: url("../img/norm_bass.png") no-repeat;
}
#bass:active {
    background: url("../img/inv_bass.png") no-repeat;
}
button:focus {
    outline: 0 !important;
}