CSS Not in ftp files, but in source code

I am working on a wp site that I took over and need to edit some css and it is not there in the style sheets nor any of the php files on the host. The source code says otherwise.

Below is the code I want to change (height from 415 to 615) and I cannot locate the css in the ftp. I also checked these files in the index.php, header.php, front_page_template.php, page_no_sidebar.php. This is the reFresh Light template. I am not a wizard at all with wp yet so any suggestions would be appreciated. Thank you.

Line 450 in source code I actually want to chage from 415 to 615 and cannot locate it.
.one_third {
float: left;
width: 300px;
margin-right: 13.5px;
height: 415px;
padding-right: 13.5px;
border-right: 1px solid #666;
margin-bottom: 0px;

If you need additional information please let me know.

Again thank you.