Permission Grid: stick the headers to handle a lot of tags

[Ornanovitch]

Fixes #2810
Temporary fix before flarum/issue-archive#253

Changes proposed in this pull request:

Stick thead th and tbody th: when you have a lot of tags permissions to handle, it's more consistent to be able to see the headers you're in.

Reviewers should focus on:

To be tested with a lot of Restrict by Tag 🏷️
Does it work on safari?

Screenshot

FA isn't loaded on my local dev environment, I don't know why but it has nothing to do with this PR 😸

Confirmed

• Frontend changes: tested on a local Flarum installation.

[SychO9]

Hello!

Thank you for the PR, I have actually played with the idea a bit in the past, and really liked it.

We will review this soon when we pick up development again 🤗

[Ornanovitch]

Take your time, all of you deserve it!

I'd be glad to start trying to improve a little Flarum with my limited skill but there is no rush at all, I'll wait for your review :)

[luceos]

@Ornanovitch thanks so much, this is awesome. I've assigned a couple of reviewers in the hope to push this into the next release 🤞 . The ux on the permissions page is seriously hampered with many tags or groups, so thank you for thinking along!

[SychO9]

Nice! a few comments

Can you add to

.PermissionGrid-child {
  td, th {
    position: relative;

a z-index: 0 as it can overlap the th when hovered.

[SychO9]

Looks good to me!

[askvortsov1]

Mostly LGTM, left a nit.

Is there a reason we haven't merged this yet, or have we just not gotten around to it yet?

[askvortsov1]

I don't suppose we can avoid vendor specific stuff here?

[SychO9]

for now we need it for some old safari browsers

https://caniuse.com/?search=sticky

[SychO9]

Is there a reason we haven't merged this yet, or have we just not gotten around to it yet?

Just needed a second approval!