$opac: 0.175;
$colors: ( grn: green, ylw: yellow, crm: crimson, pur: purple, org: orange, blu: blue );

.ubx-bootstrap {
    z-index: 1000;

    &__col {
        @each $key, $color in $colors {
            &.#{$key} {
                background: rgba($color, $opac);
            }
        }
    }
    &[hidden] {
        display: none;
    }
}