rustdoc: clean up `.out-of-band`/`.in-band` CSS

* Remove the `float: right` fallback from the main header, which hasn't
  been needed since IE11 support was dropped.

* Remove `in-band` from low-level headers, which hasn't been needed since
  `.rightside` switched to `float: right` in
  593d6d1cb15c55c88319470dabb40126c7b7f1e2

* Remove unreachable `.in-band > code, .in-band > .code-header` CSS, since
  the `in-band` class was attached to the `code-header` itself, not nested
  directly below it.

* Use `rem` instead of `em` for code header margins.

* This results in a slight change in spacing around impls and item-info,
  but since it makes it more consistent with the way methods are presented,
  it's probably fine.

0 files changed, 0 insertions, 0 deletions