Use scroll-margin-top instead of pseudo hack

[MartijnCuppens]

I recently discovered the scroll-margin-top property and it turned out this was exactly what we needed instead of the hack we have. Some side notes:

• This doesn't work for IE, but since sticky itself doesn't work, this is a non-issue.
• This doesn't work for the old Edge, I'm not sure if that's really an issue since it's just for our own docs.

I've also wrapped it in a media query since the stick menu is only present above the md breakpoint.

[XhmikosR]

Not working in Edge is an issue for sure. Not going to block it though, since we are talking about a small percentage anyway https://caniuse.com/#feat=mdn-css_properties_scroll-margin-top

[MartijnCuppens]

Not working in Edge is an issue for sure.

It just doesn't work in the old edge, caniuse is wrong here. (seems to be fixed recently, but not yet updated on production mdn/browser-compat-data#5557)

[XhmikosR]

I personally meant the old Edge. Like I have mentioned in the past, browsers don't magically get updated on Windows :P Also, Microsoft hasn't attempted to replace the old Edge yet, let alone that even if they do, there are so many supported Windows versions out there.

Anyway, this is just a FYI, ideally we should have some kind of fallback, but even without it I guess we could try landing it later.

[XhmikosR]

Can't we have a fallback of some kind?

[ffoodd]

@XhmikosR by using @supports(), it should be pretty easy — however it means more code.

[MartijnCuppens]

@XhmikosR by using @supports(), it should be pretty easy — however it means more code.

This would be moot. The current implementation works 100% (but is pretty ugly), no reason to just add code.

[XhmikosR]

Technically, this does not work 100% since it doesn't work in all of our supported browsers.

Anyway, #30273 (comment)

[MartijnCuppens]

I feel the day I can convince @XhmikosR to fully drop legacy Edge support is coming closer...

[ffoodd]

Just to be sure, couldn't this be applied to sticky / fixed navbars component too?