some css not loading

Hi!
I’m using a child theme and as I always do, I’m customizing a few things in VFB forms through the child theme style.css file. Happens that I’m not being capable of doing some changes for example, change the legend color:

.visual-form-builder .vfb-legend {
color: #ddd;
}

This is not loading. Could you help please?
This is my website: https://decomds.com/

Thank you.

https://www.ads-software.com/plugins/visual-form-builder/