Skip links misplaced in the responsive view

[afercia]

When the responsive styles for the 782 and 600 pixels breakpoints kick in, the Skip links are misplaced. For the 600 pixels breakpoint they're almost completely out of the screen and barely visible.

While one could argue Skip links are not that useful on mobile devices, worth reminding many screen reader users ​use an external keyboard with their mobile device and not all screen reader users are blind.

As this seems to be a simple, quick, fix, I'd like to propose it for 5.2.1 consideration.

[afercia]

Skip links made visible for testing purposes: 782 pixels breakpoint

[afercia]

Skip links made visible for testing purposes: 600 pixels breakpoint

[afercia]

With patch applied, 782 pixels breakpoint (skip links made visible for testing purposes)

[afercia]

With patch applied, 600 pixels breakpoint (skip links made visible for testing purposes)

[afercia]

In 45301:

Accessibility: Improve the "skip links" position for medium and small screens.

Fixes #47065.

[afercia]

Reopening for 5.2.1 consideration.

[desrosj]

In 45333:

Accessibility: Improve the "skip links" position for medium and small screens.

Merges [45301] to the 5.2 branch.

Props afercia.
Fixes #47065.