How to fix sidebar

Can you make those changes and save them so i can see whats going on ?

i did save them

know that all the blogpost have this element. Those this maybe do something
https://ibb.co/R7RZYH5

I don't see those changes on this page:

https://www.kleurintens.nl/verbouwen/isolatie/wat-is-deurisolatie/

There is still padding on the image, and the sidebar is still set to 25%.

Have the changes been published in the customizer ?

Everything is right now, how you asked.

OK, add this CSS to make that block element fill the width of the content:

.single-post .inside-article > .gb-container  {
    margin-left: -50px;
    margin-right: -50px;
}
@media(max-width: 768px) {
    .single-post .inside-article > .gb-container  {
        margin-left: -30px;
        margin-right: -30px;
    }
}