Thanks for sharing your stylesheet. Skimming the code, am I not mistaken in concluding that the navigation bar will still be shoved to the top of the page?
Since that applies to sites for which CSS is entirely disabled, it tends not to be an issue (some sites use in-line styles, causing problems).
That said, there's a separate "annoyances" CSS (which I don't believe I've posted though you might find a copy via DDG/Google) which attacks a whole slew of other gripes: headers, footers, interstitials, modals, flyovers, etc. It's very broad (e.g., [class="modal"], [id="modal"], modal, ..., with a bunch of similar patterns for annoyances. I've got to explicitly override those on selected sites, particularly where they use confirmations and other dialogs.
I forget just who it is that said this, but the problem isn't so much HTML, as that there's no single entity in the role of enforcer to require that what's posted as HTML is actually sane HTML.
It's possible to do _very_ good things with HTML, CSS, tables, and Javascript even. I've done a few things myself of which I'm somewhat proud (my CodePen, referenced earlier in this thread, carries a few examples). But, as with much else, it's possible to throw out complete crap.
And browsers will render it. They've got multiple sets of quircks and brokenness modes to deal with just such issues.
Search engines will index that crap. Hell, many SEO optimisation techniques themselves are based on abuse of HTML (keyword and other semantics stuffing).
Tools that simply say "fuck you" and stop rendering shit content, or just do what the user actually wants, would go a large step toward fixing this. Various ReaderMode tools (now on Safari and Firefox) are a key example. I'm actually using the latest Firefox for Android and it specifically addresses a number of my own key browser grips in at least part (though by no means all or completely).
Google's Chrome is actually about the worst of browsers from this perspective, it's leaning far too much in the direction of yielding full power to Web authors. Yes, it's possible to create some slick Websites in that process, but you and up with gobs and gobs of shite.
Honestly, I miss the days when Netscape Navigator would just halt rendering in the middle of your page, saying, “No, I will not parse any more of your shit until you fix it.”
