Stabalize scrollbar gutter so the header stops shifting when search opens

[enf0rc3]

Focusing the search hides the body overflow to lock scrolling. That takes the scrollbar with it and widens the viewport, so both fixed headers grew and their contents jumped 15px to the right.

scrollbar-gutter: stable on html holds that width open, so the viewport stays a constant width whenever anything locks scrolling.

This was "worse" on the new navbar and resolutions that are "tight" on space.

Before:

scrollbar.mp4

After:

scrollbar-after.mp4

🤖 Generated with Claude Code

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[borland]

Do we need this?

• I can't repro the problem your video shows, on octopus.com/docs or anywhere else.
  • Observing it in the video, it's a really minor bug that people are unlikely to notice
• The new nav and upcoming search work is likely to change this stuff anyway, these additional changes might just get in the way

[enf0rc3]

This bug actually showed itself during testing of new-nav, as it looked worse with the new design, but @rosslovas suggested:

I think we're gonna revamp the actual search functionality if I'm not mistaken so we can check for this issue with whatever we replace it with, and fix if necessary

And i figured:

Ill ask claude to do a pr, if its easy fix we can merge

---

I agree with you, it is a minor impact.

I do not think the change will "get in the way" given its fix was trivial css changes that would be easy to revert anyway.

Proof of new nav fix: left (changes, right original)

newnav.mp4