Backgound images in post

Hello,

I’m building a website with evolve+ , I have only one problem though..
Every time I post an image in the text area, it comes with a rectangular background behing it, my images are png images with transparent background,
How can i make that rectangular looking background behind my images go away, or make it transparent ?
Can I do it with some css code ?

Here is the link to an example page
https://www.foodcom.be/ingredienten-db/basisproducten/bind-geleermiddel/

Thank you