Global Parameter for Widget Style doesn't work

I’m trying to get the font size increased to 150% across all widgets. Using global_parameter doesn’t change the font size. I checked the compiled HTML and font-size is unchanged. Has anyone done something similar before?

global_parameters:
widget_style: “font-size: 150%”

widget_style isn’t supported in global parameters - the way to do this would be to do it per widget definition (annoying I know) or you could create a new skin.