Login page displays the admin theme logo

[olafgrabienski]

Description of the bug

When you show the Simplified login pages introduced in Backdrop 1.30.0 and use the admin theme for those pages, the Logo setting "Use the logo supplied by the active theme" on the "Site information" page results in a login page that doesn't display the logo of your frontend theme but the one provided by the admin theme, e.g. the Backdrop logo for Seven.

Steps To Reproduce

To reproduce the behavior:

1. Spin up a fresh Backdrop site, version 1.30.0, or update an older site to Backdrop 1.30.0.
2. Make sure, Seven is the admin theme.
3. In the installer, choose a frontend theme that provides a logo, e.g. Shasetsu, and set it as default theme.
4. Of the Login page options at the bottom of the page admin/config/people/login choose "Show simplified page" and enable "Use the administration theme for simplified login pages" (default setting for new sites).
5. Go to the "Site information" configuration (admin/config/system/site-information), scroll to the Logo settings, and enable the checkbox "Use the logo supplied by the active theme".
6. Clear caches.
7. Log out, or open the site in another browser, and go to the Login page.

Actual behavior

The Login page shows the Backdrop logo.

Expected behavior

The page shows the logo from the default frontend theme.

[olafgrabienski]

As mentioned during the weekly meeting, the current behavior is 'logical' from a technical point of view, but it's not what people would expect or even want.

Recording of the topic in the weekly meeting of January 23, 2025: https://www.youtube.com/live/ObNrrDKUJDI?t=1858

[olafgrabienski]

One idea raised by @quicksketch in the weekly meeting was to not display the Backdrop logo for Seven on the login pages, also because it's not displayed anywhere else when you use the theme. I like the idea. What do others think?

[indigoxela]

because it's not displayed anywhere else when you use the theme...

That's almost true, as it's displayed on - for example - the update page:

But on the login page it doesn't make much sense. I belief, we agree here. (Why the admin theme is even usable for the login page, and is the default is completely off topic here. 😁 )

[izmeez]

Part of the reason this is convoluted is because the Default Administrative Layout does not have a Header block in the HEADER region.

If the Header block is added there is now options to show logo, site name and site slogan.

These may not behave quite as you expect, but now you can see.

The update page is different, it doesn't use a layout and already designates a spot for the logo.

When admin/config/system/site-information is set to use the logo supplied by the active theme: site side it will show theme logo and on admin side it shows the Backdrop logo with the Seven theme.

When the Header block is added to the default admin layout and show logo is checked the same thing happens: site side it will show theme logo and on admin side it shows the Backdrop logo.

This suggests that the Backdrop logo is the default logo for the Seven theme and by default only visible on the update (non-layout) page.

One the other hand if admin/config/system/site-information is set with uncheck use logo by theme and instead uses path to custom logo: the logo will show on both the site side and on the admin side, if the Header block is added to the default admin layout, and it also shows on the update block. It may also show on the login block. I'll have to test.

[olafgrabienski]

@izmeez Thanks for your input. Your comments have made me more aware that the wording of the option "Use the logo supplied by the active theme" may not make the crucial point clear enough: That it could indeed be the admin theme which supplies the logo. When I saw the word "logo" in this context, I never thought at the admin theme. So, I think it would be good to provide a description text which makes things more clear.

Apart from that, I'm still for changing the behavior. Either just not show the admin theme logo on the login page (as suggested in a comment above). Or change the form on admin/config/people/login, so that the problematic option "Use the administration theme for simplified login pages" isn't anymore the default for new sites.

[izmeez]

I repeated the steps described in my earlier comment with the Gin theme as the admin theme. The Gin theme has a logo and it is BIG. There is no css sizing in the admin layout.

Three things come to mind.

1. Seven should not have a logo. Otherwise it will need it's own to avoid future confusion by using the Backdrop core logo.

2. The admin layout in core will need css sizing for the logo in the admin layout. There may already be css sizing for the update block and sign-in block. When site information logo settings specifies a path to a logo, the logo will be shown in the admin theme and needs to be appropriately sized.

3. When code checks site information, logo settings option: use logo supplied by theme; if it is selected and this is an admin theme, return display nothing on admin layout or blocks (update block, sign-in block, etc. )