Hi domir21,
I can not access your backend to check the issue. However, I think you can try the following solution:
1/ Edit the VirtueMart Category module > Advanced tab and add a custom class to the module:
And add the following CSS code to the Tools > Custom CSS:
.section-custom-col-4 .width20 {
-ms-flex: 1 0 20%;
flex: 1 0 20%;
max-width: 35%;
}
Hope this helps!