.si {
    display: inline-block;

    width: 1em;
    height: 1em;
    line-height: 1;
    vertical-align: text-top;
    fill: currentColor;
    &.si-lg {
        width:1.333em;
        height:1.333em;
    }
    &.si-sm {
        width:0.875em;
        height:0.875em;
    }
}