Including two classes in one button

I'm working with a rich text button. The button is on a parent record. The user clicks the button, the parent is saved, and then a popup opens to add a child record. When I add the savebeforenavigating class, the button stops opening the window in a popup and instead opens in a new tab.

Is it possible to include both classes in the same formula?

var number rid = [Record ID#];var text url = 
URLRoot() & "db/" & [_DBID_CHILDREN] & "?a=nwr" & "&_fid_10=" & URLEncode($rid) & "&ifv=1" & "&hs=1";
var text color = "#228B22";
var text txtcolor = "White";

"<a class='SaveBeforeNavigating' & \"OpenAsPopup\" data-height=\"800\" data-width=\"1000\" data-refresh=\"true\" " &
 "style=\"text-decoration: none; text-align: center; background:" & $color & "; color: " & $txtcolor & "; border-radius: 5px; margin: 2px; padding: 5px 5px; width: 100px; display: inline-block; font: 14px/ 'Calibri', 'Segoe UI', sans-serif; text-shadow: none;\"href='" & $url & "'>Add Child</a>"