Main background image

Hi

Apologies if this has been previously answered, but I’m having difficulty with my site’s background image:

http://crystal-blue-dreams.com/

As you can see, I can’t get it to span the entire page. I inserted the image into my twenty twelve child theme using this CSS:

html {
background: url(‘http://crystal-blue-dreams.com/wp-content/uploads/images/cbd-main-background-1.jpg’) no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}

And then found that I needed to remove this from the main stylesheet:

body {
background-color: #e6e6e6;
}

This had it working, but then today, I went into the theme manager to change the site strapline and the image has now reverted.

Does anybody have any advice on how to fix this?

Thanks in advance.

Paul