I am confused how to have a div where the border would be only visible on half its width. The border style is a simple 1px solid #000;

However, I want the top of the div's border to not be visible everywhere (on 100% on the div's width), rather only on the first 50% of the div's width.

I haven't been able to get an example of this anywhere, and it needs to be in percentages, so the usual bag of tricks (image over the second half,...).