CSS for Child theme

I can't seem to get my custom CSS to work in the child theme.

I have set it to "default" and renamed the child-sample-style.css to child-style.css (and moved it to the root of the bp-fun-child folder with style.css, which it does not say to do but it doesn't show up otherwise.

At present I am trying to acomplish a very simple css change.

I want to change this

#top-header .top-h {
  padding: 2%;
  width: 96%;
  margin: 0px;
  float: left;
  background: #FFFFFF;
}

to this

#top-header .top-h {
  padding: 2%;
  width: 96%;
  margin: 0px;
  float: left;
}

Note the lack of the background color. I tried it in the style.css file and the child-style.css and get nothing...

Also, I'd like to mention that one of the reasons I joined was that all the themes are supposed "well documented" and "come with a manual" which I rarely see in any of your themes.