Rich Text Editor Press "Enter" get two carriage returns

Support
11

I had a lot of trouble finding a way to stop the double spacing after entering return - and all the suggestions I cam across were wrong!
It's actually quite easy - add this code to the, "Custom stylesheet for rendered markdown"

p {
font-size : 15px;
background-color : #ffffff;
padding : 0;
margin : 0;
line-height : 20px;
}
#p2 {
background-color : #ffffff;
}