[v2] Positive Tabindexes

[isralduke]

Two items Topbar include have positive tabindex values. This is considered bad practice for accessibility. They exist because they were a part of the third-party code used in the early versions of Pelican. The markup should be refactored so that the tabindex values aren’t necessary.

File: _includes/markup/app-screen.njk
Line: 55, 60

File: _includes/header.njk
Line: 3, 9

File: _includes/sidebar.njk
Line: 4

File: _includes/markup/sidebar.njk
Line: 11, 57, 62

File: _includes/markup/skip-link.njk
Line: 1

File: components/app-screen.md
Line: 71, 76