Bunce,

 

I think we can work it out.

 

In the CEHtmlEditorProvider.vb file, you can find the following code:

 

 

With the above code, we tell the editor using multiple Style Sheets the for the editable area.

Solution 1: 

    Find  the location of containing style sheet, and append it to EditorWysiwygModeCss property:

    EditorWysiwygModeCss = s1 & "," & s2 & "," & s3 & ", " & s4 & ", yourscontaining.css"

Solution 2: 
    
    Create a new style sheet and paste the style sheet you want to use in the editable area, and append the new style sheet to EditorWysiwygModeCss property:

    EditorWysiwygModeCss = s1 & "," & s2 & "," & s3 & ", " & s4 & ", mystyles.css"

Hope it helps.

Keep me posted.