This issue combines the following three related issues into one piece of work.

• is it clear which page element has focus from the keyboard? #3933
• OLH theme mini-bar is wider than the main content #4340
• Add share links to all themes #1863

The plan is to:

• update the share links on the OLH theme to
  • make the tab order the same as the visual order
  • [redundant] include aria labels
  • be positioned correctly within their containing div (see OLH theme mini-bar is wider than the main content #4340)
• Update the Material and Clean themes to match this update, tweaking it to fit their styles.
• update Twitter to X within these share buttons