Bold font rendering doesn't work in web TV app

I have created a hosted TV web app. But somehow, whatever I do, I cannot change the font-weight of my rendered font. Whatever I do it keeps stuck at 400.

Even when I set my font to Arial (in other words: no custom font).

It seems to happen only when I distribute my app to an IPK file. While debugging this is not an issue.

Does anyone know why? And how to fix this?

Please make sure your fonts are referred to relative to the location of the index.html file. You can find more information in Fonts. Thank you.

But Arial is a web-safe font. Not a custom font. So a bold font should work out of the box.

Due to graphic quality issues, webOS TV does not support CSS for font effects(italic, bold, etc.). Please use separate fonts for each effect. Thank you.