Preview, Save & Continue, Save & View and Cancel buttons unreadable using Colibri skin

Using XWiki Enterprise 3.5.1 and the Colabri skin, when editing a page using either the WYSIWYG or Source links, the buttons for Preview, Save & Continue, Save & View and Cancel are unreadable.

If I switch to Toucan skin I can see them. I was able to get around this issue in the Colabri skin by changing the \resources\js\smartclient\skins\Enterprise\skin_styles.css file (starting at line 118) to appear like the following:

.buttonSelectedDisabled {
padding:2px;
font-family:Arial,Verdana,Bitstream Vera Sans,sans-serif; font-size:11px;

/*============================================================
Temporarily Removed to Clean up Button Issue
background:#DDDDDD url(./images/cssButton/button_stretch.png) repeat-x;
============================================================*/
color:#000000;
border:1px solid #A6ABB4;
}

I don't know what other areas this may impact, but this change now makes the buttons appear like they did in our prior version (XWiki Enterprise 3.4 using Colabri skin). We are going to try running like this for now to see if anything else is affected by this change.