bug(docs): toc is not sticky

[donroyco]

Bug.

Mozilla Firefox: Not sticky
When navigation in Mozilla Firefox version 55.0.2 on a components page while scrolling down, the table of contents won't stay at the top of the viewport, but just scrolls along with the rest of the content.

Apple Safari: Bottom of page
In Apple Safari, version 10.1.1, the table of contents is at the bottom of the page (below screenshot) and also not sticky, but this may be a side effect of #247 | #248

Browser
Mozilla Firefox, version 55.0.2
Apple Safari, version 10.1.1

What else?
No errors in console.

[amcdnl]

@jelbourn - In Safari, you can toggle various different parent elements display properties and it starts working. For instance, toggling this: in the dev tools makes it work, however, if you set it via css or even programmatically in JS, it doesn't work. I'm guessing this is a reflow issue.

@donroyco - It seems to work on Firefox after #247.

[donroyco]

@amcdnl Thanks for looking into this.

[annieyw]

Fixed in oktav777#1

[Splaktar]

It looks like PR #362 is still open to solve this. Though it hasn't been rebased in a few years. I'm not sure if it's still relevant/needed?

[Splaktar]

I closed #362 since similar changes were made in PR #840, but they did not fix the sticky TOC issues.