Not sure where I originally saw it while lurking around the forums, but someone, somewhere at some time was asking about styling Uikit checkboxes as toggle-style switches, much like the ones at the bottom of this post asking me if I want to be notified of replies. So here is my humble offering, rough and ready,  which can be thrown in at the bottom of your Uikit css as a starting point. Everything is based on ems and rems, so you can increase size as you desire by altering the single i