Making .section_wrapper container 100% width

skogenlol

Hi, im trying to increase the width of the header .section_container so i can create something like this;

https://ibb.co/d26TM5 - with customization

https://ibb.co/hBqf15 - without customization

But it doesnt seem to allow me to change with adding custom CSS, after i save it doesnt appear on the page