Notes
For components and frames this is now possible via the + inside Styles, but if you want it on the page level you'll still need this code.
Hit copy and then paste this code into the 'Start of <head> tag' section in your site's custom code. Either set it per page or add it to 'General' to apply it site wide.
Won't work with Safari based browsers.
Tip: shift + , will take you straight to your page settings.
Help
How do I add code overrides?