After upgrading Web dll's from version 2012.n to 2015.n using their installer and upgrade wizard, the CSS background-position property for the RadTreeView's tristate.png (checkbox image) is being set to incorrect values regardless of what settings are in the CSS file. Inspecting the element values in IE says that hte values are being set by the WebResource.axd file (which is generated dynamically at runtime). The values in the TreeView.css file are:
.RadTreeView .rtChecked { background-position: 0 0; }
.RadTreeView .rtUnchecked { background-position: 0 -13px; }
.RadTreeView .rtIndeterminate { background-position: 0 -26px; }
However the values are being overridden incorrectly to (IE Dom Inspector):
.RadTreeView .rtChecked { background-position: 0 -40; }
.RadTreeView .rtUnchecked { background-position: 0 0; }
.RadTreeView .rtIndeterminate { background-position: 0 -80px; }
Setting the .css file values to !important doesn't override the "axd" values. Does anyone have any idea where these unwanted background-positions values are originating from, or help me understand what happened during the upgrade that caused these settings so I can correct the problem?