Text With White Background
Use the &quot;Inverted&quot; button under the &quot;Font Type&quot; heading:


Instead of placing the text in silkscreen, it will create an outline in silkscreen and allow the soldermask color to show through where the text is located. In other words, this gives you a border and transparent text.
If you want your entire board to be white, you'll need to instead specify white soldermask and black silkscreen when ordering the board from the manufacturer. In this case you would leave the &quot;Inverted&quot; button deselected. This won't give you the border though, this will just put black text on the overall white board.