Rollup merge of #131906 - notriddle:notriddle/spacing, r=GuillaumeGomez

rustdoc: adjust spacing and typography in header

Fixes #131589

Preview: https://notriddle.com/rustdoc-html-demo-12/spacing/std/index.html

| Before | After |
|--|--|
| ![image](https://github.com/user-attachments/assets/b5c5132d-1e5e-402e-ba19-1dea9e70ea6f) | ![image](https://github.com/user-attachments/assets/72570b93-bb16-4553-9da7-fc4f29b98873)
| ![image](https://github.com/user-attachments/assets/264983f0-5aec-4120-8a03-f62e52d4360d) | ![image](https://github.com/user-attachments/assets/b6925945-95e6-4858-8e91-4cfd90c164f0)
| ![image](https://github.com/user-attachments/assets/df96bfe7-195d-4aaf-97f1-a45ade34cab2) | ![image](https://github.com/user-attachments/assets/c6fe2d57-bd8a-42aa-b3cf-4f635809b9b4)
| ![image](https://github.com/user-attachments/assets/7519faa5-d6b2-41ba-9d95-6000d1dd89d1) | ![image](https://github.com/user-attachments/assets/7233c2d6-82d9-4820-bb63-dc4776a34601)

First of all, we put 4px additional margin below the search box, and 4px margin below the header to balance it out.

The bigger problem we have to solve is making the lines look logically spaced. This is troublesome, because Fira Sans (the typeface we use here) wants to look good on average, and to avoid breaking, with text that uses [ascenders and descenders](https://www.w3.org/TR/css-inline-3/images/text-edge.png). If the text we're putting in happens to not have any, things look weird (strictly speaking, there’s hand-tuning here, because the Copy Path button messes with stuff, but the overall point is that there is no true, one perfect layout).

In order to play nicely with the font, I've tweaked the text to use that space. The word "Source" for the link is now capitalized, and the Since version number now uses oldstyle nums with descenders.

0 files changed, 0 insertions, 0 deletions