This issue aims to improve consistency in header layout, metrics, etc. across all block editor instances. As far as I've researched, I think the following improvements and bug fixes are needed.

Related PRs:

• Update main toolbar buttons to all be compact #56635
• Clean up header toolbar metrics and responsive break points #56729

Improvements

✅ Change header height from 60px to 64px

• Change header height from 60px to 64px #60729

Target: Post Editor, Widget Editor, Site Editor

Also mentioned in this comment

Fixed

✅ Focus ring cut off

• Post Editor Header: Make block toolbar toggle button focus visible #59781

Target: Post Editor

We'll probably need a 2px margin on the left, like in the Site Editor.

✅ Standardize button size to 32px

• Editor: Standardize header button size to 32px #58532
• Site Editor: Standardize block tools toggle button size to 32px #59625

Target: Post Editor, Widget Editor, Site Editor

Some buttons remain at 36px. Regarding the Widget Editor, note that we cannot refactor it with the DocumentTools component of the @wordpress/editor package. Please refer to #57660 for details.

Post Editor:

Widget Editor:

✅ Overflow occurs

• Apply custom scroll style to fixed header block toolbar #57444

Target: Widget Editor

✅ Border misalignment when Show "button text labels" is enabled

• Block Mover: Unify visual separator when show button label is on #59158

When the mover button is horizontal, the border should be vertical.