Change fontsize for userContent ?

[SheepDomination]

I want to change the size the

tags on the reddit.com web site; therefore using this rule for this selector doesn't work when applied to userContent.css ?

  @-moz-document url-prefix("www.reddit.com") {
    .text-14, .text-14\/5 {
    font-size: 2.0rem;
    }