Invalid CSS in oae.base.css

Checking the QA1 build, `oae.base.css` has the following:

    body, button, input, select, textarea {
        font-family: 'Open Sans', sans-serif; arial, helvetica, sans-serif;
        line-height: 1.5;
    }

Note the semi-colon after the first instance of `sans-serif`. It should be a comma. (And presumably the first `sans-serif` shouldn't be present at all since the font is repeated at the end of the list.)