Ability to change the focus indicator (accessibility, enhancement)

[cygnus-glacier]

When pressing tab to navigate by links, the focus indicator around the links is very faint and hard to see. Can we add a way to change this in the Style tab?

Some helpful things to edit might include:

• dash style (solid, dashed, etc)
• border thickness (1px, 2px, etc)
• border colour (hex code or colour picker like other style options)
• change the background colour of the link focus (like setting background-color for in CSS)
• change the colour of the text of focused links
• option to remove the focus border if deciding to use a background fill / text colour change instead