teaser calendar

Migrating from Joomla3.x to Joomla4.4; for that I created a subdomain, updated plugins (), updated Joomla. Unfortunately the Calendar Teaser is not shown. See appended images.
HTML/CSS-code seems to be ok:
<div class="calendar-red jem-teaser-calendar" title="Fr, 24. November 2023, 19:30 h - 00:00 h">
<div class="monthteaser">
November </div>
<div class="dayteaser">
Freitag </div>
<div class="daynumteaser">
24 </div>
</div>

Who can explain this? Who's got the solution?

Greetings

EDIT in other post:
The update of JEM was Jem 2.x to Jem 4.2

Hi fmartin,

Do I get you right: One image is the Calendar Teaser in JEM 2.xm which is ok, the other one from JEM 4.2 which is broken?

It could have many reasons.
Can you give us the URL of your website, so we can check it out.

Sorry, it's not possible. The Joomla 4.4-Website is not on the WWW

Difficult to say what the problem is. Seems as if the css file for Calendar Teaser is not loaded.

thank you for your answer. But where can I see if mod_jem_teaser.css is loaded or not? And how can I load it in case it's not loaded?
Greetings
Martin

In you browser you can display the source code.There you look for

At least one of the yellow ones must be there, the orange ones are for color and icon fonts.