Height of "collapse" button's line on IRC layout should be reduced

[luixxiul]

Steps to reproduce

1. Enable IRC layout
2. Open #matrix:matrix.org
3. Look for events summary
4. Click expand

Outcome

What did you expect?

The spacer line's height should be expected to be same as others, according to the declaration line-height: $irc-line-height !important; on _IRCLayout.pcss.

What happened instead?

The same spacer line's height is used for both IRC layout and modern layout.

Operating system

No response

Application version

b48d568

How did you install the app?

yarn run start

Homeserver

No response

Will you send logs?

No