dojo DataGrid css and LESS compilation error

[vincent-ks2]

Hi,
I want to use a basic dojox/grid/DataGrid into my custom Aikau widget.
When importing claroGrid.css file, I got the following LESS compilation error:

2018-06-07 19:36:41,428 ERROR [extensions.surf.LessCssThemeHandler] [http-apr-8080-exec-9] LESS for Java Engine error compiling: '': com.asual.lesscss.LessException: Parse Error: Unrecognised input (line 3573, column

1. near
   background: -webkit-gradient(linear, left top, left bottom, from(#EDF2F7), to(#D0DFEA));
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#FFEDF2F7, endColorstr=#FFD0DFEA);
   border: 1px solid #FFFFFF;
   at com.asual.lesscss.compiler.RhinoCompiler.parseLessException(RhinoCompiler.java:118)
   at com.asual.lesscss.compiler.RhinoCompiler.compile(RhinoCompiler.java:69)
   at com.asual.lesscss.LessEngine.compile(LessEngine.java:102)
   ....

When removing the section below from css file it looks ok, but I don't want to modify or copy the standard dojo lib.
/*
.claro .dojoxGridMasterHeader {
background: url("images/header.png") #EDF2F7 repeat-x bottom;
background: -moz-linear-gradient(top, #EDF2F7, #D0DFEA);
background: -webkit-gradient(linear, left top, left bottom, from(#EDF2F7), to(#D0DFEA));
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#FFEDF2F7, endColorstr=#FFD0DFEA);
border: 1px solid #FFFFFF;
border-right: none;
}
*/

Any advice on how to cleanly make use of DataGrid in Aikau?

thks,
Vincent