fix(app): tighten up session padding-top for mobile

[DNGriffin]

What does this PR do?

tightens up the extra padding in primary session pane. Current styles give you more padding on smaller screens. Should be less padding on small screens IMO.

Mobile has much less space to work with, needs all the session space it can get.

Before:

After:

Video showing breakpoint transition:

Screen.Recording.2026-02-03.at.9.46.18.PM.mov

How did you verify your code works?

Tested

Fixes: #11245

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Based on my search, I found one potentially related PR:

Related PR:

• fix(app): comprehensive mobile UX improvements #7989 - "fix(app): comprehensive mobile UX improvements" (fix(app): comprehensive mobile UX improvements #7989)

This PR might be related since it addresses overall mobile UX improvements, which could include session padding and layout adjustments. However, PR #11247 appears to be a more specific, targeted fix for session padding on mobile screens, so it's likely a distinct improvement rather than a duplicate.

The search didn't find other PRs specifically addressing session padding or mobile responsive padding adjustments.

[Brendonovich]

imo a little bit of top padding here would still be nice, perhaps pt-2? will have to check the design docs at some point later to see if this was intended.

[DNGriffin]

imo a little bit of top padding here would still be nice, perhaps pt-2? will have to check the design docs at some point later to see if this was intended.

going from pt-6 -> pt-2 is a nice conservative improvement for mobile so i'm for it

(no padding is my pref but will take the win :) )