I have a content/sidebar right setup and I am trying to reduce the side margin on the left and right between the edge of the screen and the content/sidebar in the center. Right now, the content/sidebar make up about 55-60% of my screen, and the rest is white background. How can I expand the content/sidebar right and diminish those wide margins?
that Site has some Custom CSS to keep the blog post narrow ( was originally designed without sidebars ). So go to Customizer > Additional CSS and look for and remove this: