Improved styling of tables in docs

[blighj]

Addresses #2128, PR is a follow on from #2129. The various comments have been addressed.

For the row highlight I went with a color-mix approach, making it 5% darker/lighter for even rows and 10% for hover.
That is less colorful than what was there from the previous PR and my original prototyping. I'm still happy with it.

Color-mix is supported since May 2023 according to caniuse and mdn. I put in a fallback for the even row highlight, but the hover is more additive so I left it out.

It's subtle in darkmode, but its a tradeoff with color contrast.
Currently the dark-mode hover highlight is already slightly outside AAA. If we aim for that, I'd recommend droping the hover highlight in darkmode, like I said above, additive.

If you are reviewing this, worth checking out how it looks in places with lots of tables near each other like
/en/dev/ref/templates/builtins/#floatformat

and somewhere with an example box (which has a similar background) right above a table
/en/dev/ref/templates/builtins/#yesno

[ronnzw]

Thank you very much for your PR, I'm not sure if you are aware that we have plans to design the website. I wouldn't want to see such a fantastic work not being utilised. @sabderemane might be in a better position to advice.

[sabderemane]

Late reply, I'm sorry but I think that make sense to get this on before the redesign phase, at least it will be used until the redesign and it's definitely an improvement ⭐