.filter{
    margin: 0 0 1rem; text-align: center; font-size: 0;
}
.filter > li{
    display: inline-block; vertical-align: middle; font-size: 1rem;
    padding: 0.25rem; 
}
.filter > li > *{
    display: block; padding: .25rem .5rem; background-color: #CCCCCC;
    color: #FFFFFF;
}
.filter > li.active > *{
    background-color: #2199e8;
}