At present, <base> is the same for all pages, which means you can't use relative URLs. This was introduced for good reasons, but it turns out to cause problems.

I'm not sure that it can be removed without breaking base URL functionality though — for example, things like this would break:

<link rel=stylesheet href=global.css >

.thing { background-image: url(images/whatever.jpg); }

Also, this.fetch(relativeUrl, ..) is tricky, because it needs to be relative to the page you're going to, not the page you're currently on, so it can't just straightforwardly delegate to fetch as it currently does.

It might be that the solution is just to not use relative URLs 😬 Unless there's already a creative solution for this problem?