nts-button-toggle {
    nts-button.pressed button {
        box-shadow: rgba(0,0,0,0.1) 1px 1px 2px inset;
        background-color: $alpha-black-medium;
        &.primary{ background-color: darken($color-primary, 10%); }
        &.error{ background-color: darken($color-error, 10%); }
        &.warning{ background-color: darken($color-warning, 10%); }
        &.success{ background-color: darken($color-success, 10%); }
        &.light{ background-color: darken($color-grey-medium, 10%); }
    }
}