Stylish is one of my must have browser extensions in both Chrome and Firefox. It lets you run custom stylesheets on the websites you know and love. You can even share the styles with other users on the userstyles website. For example, the Github Dark user style makes the hours a day I spend on Github much more pleasant.
I also spend a lot of time on Reddit. Unfortunately, the site is pretty hard to use on my laptop’s tiny screen due to the large sidebar on the right of the page.
Well, I created a style to hide the Reddit sidebar and maximize the main content area.
p.s. I know, my sidebar is pretty wide right now, too.