[dredmorbius]

Generally, do not hijack user experiences.

Scrolling, highlight/selection colour, fixed-position elements (I've ended up nuking your site's header entirely), autoplay audio/video, mouse action, click actions (either opening left-click in new tab, or center click in same tab), etc.

All violate the principle of least surprise/astonishment. Quite annoying.

[gambiter]

> highlight/selection colour

You can have your horrible purple/blue... I'll take people hijacking those abominations any day of the week.

Otherwise, that's a good list. :)

[dredmorbius]

If you don't like the defaults you can change it to what you want with a local default stylesheet. The issue isn't that the default is sane but that changes from default are jarring.

White text on a blue field works well for me.