For optimisation what I would do is move all the styles over to
fluid.css, get rid of the inline style-block in the HTML head. Save a few so-called http-requests, and by doing so make the very first loading of the site faster. Those
@import statements loading the stylesheet with the (webfonts) font-face declaration are also rather costly in terms of rendering, so by having just one stylesheet this would not be needed. Just have the font-face declaration on top of the one stylesheet (or use Google webfonts like I did in the Codepen demo).
BTW there is an error right in top of
boilerplate.css (the fontface-declaration missing a closing curly bracket
}) preventing (all? or) at least the
clearfix styles from rendering.
There are more issues with the CSS like using ID’s in the CSS ISO classes (extreme hight specificity making it difficult to override), the long line-length of paragraph tags, (make the text more difficult to read). Also in the HTML markup, for example the header could be just that in the markup
header ISO a
div, but that maybe something for another thread.