Page Builder Looks Weired

Hello,
I installed Museum template for my Joomla 4 website. 
And made Sparky Page builder as my default editor. 
But when I try to add new content or edit old ones, I get this, which does not look like a normal look of page builder:
 
 
I tried installing page builder again, to no avail. 
 

Hello,

Try clearing the browser cache or try with a different browser. If it doesn’t help, try reinstalling the Sparky Page Builder (use version for Joomla 4).

If still doesn’t work, please send access to your Joomla administrator so we can check this. You can post this on the forum privately if you select a part of the text and click the "lock" (confidential) icon.

Regards,
Milos