Simple Catch "dark.css" file

http://themes.svn.ww.wp.xz.cn/simple-catch/2.6.7/css/dark.css

You really shouldn’t be making changes to the theme files at all – as those will be erased when the theme is updated. Instead make your changes in the custom CSS option in that theme.

But to answer your question, the first error here shows that it’s not finding a CSS file:

http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fmycfotestsite.x10.mx%2Fwp%2F&profile=css3&usermedium=all&warning=1&vextwarning=&lang=en