- Add border radius of 4px to select and buttons
- Add padding left and right for header
- Reduce caret-padding 'cause now we have left-padding from header
- First moz-button should have 4px margin spacing on the right
- Add margin-block: var(--space-xsmall) to select element to make header 40px.
Differential Revision: https://phabricator.services.mozilla.com/D228680