Craigles700 are you using a theme at all? I ask because sometimes themes change the default font and size. If you're just on the standard default theme then I'll take a look tomorrow as I'm closing down for the night and I'll get back to you; in the meantime let me have your site address and I'll look at what's in there. If you don't want to post it in here, send me a PM. As an aside I've had to mix it with the CSS that I previously mentioned as it was a right old mess on FF and Edge, also (as always with CSS) you get something looking the way you want and throws something else out of canter, so I've had to be a little inventive and add some additional custom CSS and change a few templates.