I've had some luck giving either an example website to ape or listing out a particular era, monkey see monkey do seems to help a bunch.

I've done each of the 3 for side projects below to pretty good effects.

> This website will be run by IE6 and Windows Mobile 6, so use no dependencies, semantic HTML, a 3-pane layout, and only use JS (es3!) where absolutely necessary (and where necessary, put the script at the end of the body).

When I'm not specifically targeting support for retrocomputers I do something like this, then iterate until it looks right.

> Go look at Dokuwiki, django defaults, and common web 2.0 color schemes, use those for UI inspiration. Keep a 3-pane desktop-first layout, but enable mobile responsiveness with media queries. Use semantic html5 and prefer older boring solutions like surgical jquery or htmx-style islands of interactivity where needed, otherwise do not bring in dependencies without my say so.

And finally, if I'm doing a web app that I'm vibing out with the web stack because I want it one-shotted and not trying to do a good rust core with strong ports/adapters API surface for web or native client callers, I do something like this:

> This is a local web app, the frontend, backend, and desktop are all on the same machine. Use naive and simple development patterns that you document the style as you go, pick a boring web framework and use it idiomatically, but remember that some tricks that are intended to keep network round trips down are not as necessary because network penalties are not as bad as real traffic.

Granted, the above I don't like as much, but it does produce more 'modern' looking sites by default.