CSS: Sidebar appears largely blank at mobile screens without placements

[Yanko1013]

Summary

When it's 390 x 704 in the responive view.

but once the height is less than 704px(or 44rem):

the flex layout is unavailable instead uses the gird layout, section.place.side takes the place of nav menu.

URL

example.

Reproduction steps

1. open the dev tool, use the responvie view, set like 390x704.
2. open any docs.
3. expand sidebar and resize the height.

Expected behavior

No blank between filter button and nav...and maybe we should allocate more space for the nav?

Actual behavior

large blank

Device

Desktop

Browser

Chrome

Browser version

Stable

Operating system

Mac OS

Screenshot

No response

Anything else?

No response

Validations

• I have read the Community Participation Guidelines.
• I have verified that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• I have checked that this is a concrete bug. For Q&A open a GitHub Discussion.