If the CSS isn't cached (or the cache is disabled), then the browser will briefly display most pages in tlwebadm without any CSS. Once the CSS loads, the page will adjust and look the way it is intended.
This stutter can be ugly and annoying. Most users should rarely see it, though, as the CSS should be cached after the first page visit.
This can mostly be seen in Firefox, but some effect is also seen in Chrome.
It also talks about "deferred scripts", but that doesn't seem to be necessary as an empty `<script></script>` section is enough to resolve the issue.
Need to do this now and as we need to add a script to all pages as part of bug 7909. In other words, we'll get the effect we want here as a side effect.
To avoid this detail getting lost, we'll fix this bug with something more explicit in place.
We ended up scrapping that plan for bug 7909, so this bug is back on the queue.