Fix title heading overlap in rust doc

[GuillaumeGomez]

Fixes#45158.

To be noted that this margin only appears when a title is the first element.

r? @rust-lang/docs

[GuillaumeGomez]

The second commit removes the top margin when a title is the first element of the text:

[killercup]

Hm, this is not how I would would fix. Why give this header a margin-left, when all other headers with collapse buttons next to them don't have one? It makes the layout look quite unbalanced to me.

In addition, it still has weird spacing on hover as the collapse button and the section link marker overlap:

I'd suggest getting rid of the "§" pseudo-element for the first header (.docblock > .section-header:first-child a:before { display: none; }) and adjusting the line height and spacing of the toggle button so it is one the same visual line as the headline (h1.fqn + .toggle-wrapper a { line-height: 33px; padding-top: 3px; }).

[GuillaumeGomez]

I thought at first about removing all "§" but it seemed inconsistent with the rest. Therefore, I came up with this solution which still seems the best for me. I don't feel like the rendering is unbalanced, and this is something we quite often around. However, if a majority of people thinks the same as you, I'll just update this way but I really don't like this idea.

[steveklabnik]

I told @GuillaumeGomez I'd check this out, but I am terrible at CSS, so I don't have any strong opinions here.

[GuillaumeGomez]

Well, talk about the design then. Does it seem good for you from this perspective?

[QuietMisdreavus]

Plain:

Hover:

This is Chrome on Windows. Unless there's something else going on in other browsers on other platforms, this looks Good Enough for me. Farther tiny CSS PRs are easy to review.

@bors r+ rollup

[bors]

📌 Commit 237ad82 has been approved by QuietMisdreavus