The maintenance page does hide the skip to main content link. This is because system.module.css is no longer added in as I think I was in Drupal 7 afaik the equivalent system css files were added during system_init() when the db was available. They are now added in system_page_build() which is not fired for maintenance pages.
Current maintenance page

| Comment | File | Size | Author |
|---|---|---|---|
| #4 | interdiff.txt | 1.33 KB | alansaviolobo |
| #4 | maintenance_page-2022765-4.patch | 701 bytes | alansaviolobo |
| #1 | Maintenance_page_after.png | 25.24 KB | alexpott |
| #1 | 2022765.maintanance-visually-hidden.1.patch | 1.27 KB | alexpott |
| Maintenance_page-2.png | 39.57 KB | alexpott |
Comments
Comment #1
alexpottWith the patch attached the page looks like this...

Comment #2
amateescu commentedIs there any reason not to move the other two calls to drupal_add_css() with the rest of the bunch?
Comment #3
amateescu commentedAlso, a site is not in an unusable state (wsod, fatal error, etc) if that link is not hidden, so I don't think this is critical.. not even major :)
Comment #4
alansaviolobo commentedthe patch didn't seem to make any difference. i guess this issue is already fixed ?
Comment #5
jhedstromThis appears to have been fixed along the way. I've confirmed that these CSS files are present on the maintenance page, and hide the "Skip to main content" as expected.