Error: Undefined variable: "$atum-box-shadow".
        on line 24 of administrator/templates/atum/scss/vendor/joomla-custom-elements/joomla-tab.scss
>>              box-shadow: $atum-box-shadow;
   --------------^

After making the suggested change manually I can partially confirm the fix.

The grey box is no longer displayed but the box is still there - this means that

1. Subsequent errors are displayed below where the previous message was
2. Any buttons that are below this now invisible box will not be selectable

The above suggests to me that your css change is just fixing a symptom and not the cause. The real problem is that closing the alert does not remove it - it just tries to hide it

The above suggests to me that your css change is just fixing a symptom and not the cause

Exactly, and it's not really a proper fix (im doing this on github's GUI...)

EDIT
NOT exactly what is happening:
Alert shows:

On close:

Alert completely removed.
Now if there is more styling on the container, that's obviously wrong, the container is there only for the positioning IIRC. If someone decided to apply more styles that's really wrong, but I think with this PR, once it compiles correctly the file everything should be ok

you know i dont like band aid fixes

@brianteeman this is a total clusterF37t!!
People decided to add animation and yet another container...

FWIW alerts already have fade in animation: https://github.com/joomla-projects/custom-elements/blob/57742d291e7e906f29f82f71505dcd33e2acf5b2/src/scss/alert/alert.scss#L72

This is a rabbit hole...

(i will not comment on people only code)

And guess what this is done in JS because the html doesnt have that fade-in class: https://github.com/dgrammatiko/joomla-cms/blob/3792219bb55a1eb71a762ef4095863c802aca3c8/administrator/templates/atum/index.php#L180

@brianteeman please re open the issue, this needs a bit work that I can't do through the github GUI

#25850 reopened as requested

@dgrammatiko thank you very much trying to fix this. Do you plan and have time to repair it later?

@alikon looks like you didnt re-open this?

FWIW #26077 is achieving the same goal, so maybe this can be ignored