Template node for body font-size

Hi there!
I am using the dahboard notification node for showing my errors in my system. Because of the small size of the pop-up Notification I wanted to get it bigger.
I thought of the template dashboard node (I wrote it with body { font-size = 50px } .
Yeah it worked! BUT... now nearly everything in my dashboard is in this size...
What do I have to do, that just this Notification node is in this bigger size?
Thank You!

The easiest way to deal with this kind of thing is with your browser's developer console.

Fire up the page, press F12 to get the dev console open. Then generate a notification and click the image icon (if in a Chromium based browser) that lets you select an HTML element on the currently displayed page. Hover over the notification and you should see how it is constructed and what CSS paths you need to use to change it.