A small UI rich text rule class that styles the word "unique" when matched. It subclasses RichTextBase and sets a yellowish Color, makes the text italic, and sets a medium FontWeight.
using Sandbox.UI;
[RichTextPanel( @"\b[Uu]nique\b" )]
public class RichTextUnique : RichTextBase
{
public override Color Color => new Color( 1f, 1f, 0.6f );
public override bool Italic => true;
public override int? FontWeight => 500;
}