Theres a Blocks tab in your settings page

Playing Divinity original sin 2, great controls on steam deck.

Here’s an extension to add custom styles to websites:

https://add0n.com/stylus.html

And this is the custom style i’ve wrote:

.container-lg{
    max-width: initial;
}

.my-3{
    margin-bottom: 0px !important;
    margin-top: 0px !important;
}