Space between nav and content in Hemingway Rewritten

There is a lot of whitespace between the nav bar and the page content, even with the titles turned off. I tried adding this with the Custom CSS Editor (as was recommended for the Hemingway theme):

.wrapper {
margin-top: 30px;
}

No matter what value I put in for the number of pixels, the space stayed the same.

I like this theme very much, but would prefer to lessen that whitespace. Can anyone help with this? Thanks.