User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-33992053-20200829152232/@comment-28518515-20200830152703

Neither of the two solutions above worked for me, so I played around with it a little. I ended up with this, and it does work. :)

.mw-parser-output a.extiw, .mw-parser-output a.extiw:active, .mw-parser-output a.external { color: #d6ad0b; }

(that is actually the yellow color you might need.)

Thank you both for your help.