@mixin entity($background-color, $color: white) {
    font-variant: small-caps;
    display: inline-block;
    padding: .2em .6em .3em;
    font-size: 88%;
    font-weight: bold;
    line-height: 1;
    text-align: center;
    white-space: nowrap;
    vertical-align: baseline;
    border-radius: .25em;
    color: $color;
    background-color: $background-color;
    margin: 0.5em;
}