Sorry, I have only browsed this on my phone and haven't looked at the structure at all..I mean the whole text of the page that says "Brutalita is an experimental font..."

I can select the text from this and copy it. When you say that the text area is invisible... you mean it's not display:none or hidden... it's the color of the background and still selectable but it's covered with white SVG glyphs? Hah... if that's what I'm understanding it's a very funny trick!