Small ui fixes

• Dont use small font size for commits list
• Use standard button size for new file
• Fix vertical align for files tab top navigation
• Add border bottom and margin for readme holder

cc @skyruler @jschatz1

Before

Breadcrumbs and buttons have different vertical align compare to branch selector

No bottom border for readme

After

Before

Commits author name is hardly readable

After

Normal font size for second row

Reassigned to @jschatz1

Small improvement to #14633 (closed)

@dzaporozhets Looks great to me. Tested and it seems to work perfect!

Status changed to merged

mentioned in commit a5fb9980

@dzaporozhets it's ok