Browser action HTML text not showing

Add-ons Development
#1

For some reason, on the browser action html, when I put some text without tags, the text flashes for a moment, then disappears. Text in buttons, for example, does show up, but not in divs or

tags (I’ve tried this with an empty css file, with the same result). I’m on Firefox 55.0.3, so I don’t think it’s outdated.

Thanks, any help would be appreciated.

(the html I’ve used to test)

<!DOCTYPE html>

<html>
  <head>
    <meta charset="utf-8">
    <link rel="stylesheet" href="menu.css"/>
  </head>

  <body>
       test123
  </body>

</html>
#2

The HTML itself works (in FF56, havn’t tested 55):

image

Why dis you include the CSS link in the example? (And btw: HTML doesn’t have self closing tags, that’s implicit in HTML.)

#3

Hm, that’s weird, because I used that same code and it didn’t work, I think it might just be my computer being having some issue. Thanks for the help!

Edit: Yeah, I tried it on another computer and it worked fine, so it’s something with my computer.