diff --git a/src/Gui/PreferencePacks/FreeCAD Classic/FreeCAD Classic.cfg b/src/Gui/PreferencePacks/FreeCAD Classic/FreeCAD Classic.cfg
index c14c75e26f..dce316a6d7 100644
--- a/src/Gui/PreferencePacks/FreeCAD Classic/FreeCAD Classic.cfg	
+++ b/src/Gui/PreferencePacks/FreeCAD Classic/FreeCAD Classic.cfg	
@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
 <FCParameters>
-
   <FCParamGroup Name="Root">
     <FCParamGroup Name="BaseApp">
       <FCParamGroup Name="Preferences">
@@ -8,133 +7,12 @@
           <FCParamGroup Name="Start">
             <FCBool Name="FileCardUseStyleSheet" Value="0"/>
           </FCParamGroup>
-          <FCParamGroup Name="Arch">
-            <FCUInt Name="WallColor" Value="3604403967"/>
-            <FCUInt Name="StructureColor" Value="2527705855"/>
-            <FCUInt Name="RebarColor" Value="3111475967"/>
-            <FCUInt Name="WindowColor" Value="556614399"/>
-            <FCUInt Name="WindowGlassColor" Value="1572326399"/>
-            <FCUInt Name="PanelColor" Value="3416289279"/>
-            <FCUInt Name="ColorHelpers" Value="674321151"/>
-            <FCUInt Name="defaultSpaceColor" Value="4280090879"/>
-          </FCParamGroup>
-          <FCParamGroup Name="Draft">
-            <FCInt Name="gridTransparency" Value="0"/>
-            <FCUInt Name="constructioncolor" Value="746455039"/>
-            <FCUInt Name="gridColor" Value="842157055"/>
-            <FCUInt Name="snapcolor" Value="4294967295"/>
-          </FCParamGroup>
-          <FCParamGroup Name="Part">
-            <FCUInt Name="Dimensions3dColor" Value="4278190335"/>
-            <FCUInt Name="DimensionsAngularColor" Value="65535"/>
-            <FCUInt Name="DimensionsDeltaColor" Value="16711935"/>
-          </FCParamGroup>
-          <FCParamGroup Name="Path">
-            <FCUInt Name="DefaultNormalPathColor" Value="11141375"/>
-            <FCUInt Name="DefaultRapidPathColor" Value="2852126975"/>
-            <FCUInt Name="DefaultPathMarkerColor" Value="1442775295"/>
-            <FCUInt Name="DefaultProbePathColor" Value="4294903295"/>
-            <FCUInt Name="DefaultHighlightPathColor" Value="4286382335"/>
-            <FCUInt Name="DefaultBBoxSelectionColor" Value="3372220415"/>
-            <FCUInt Name="DefaultBBoxNormalColor" Value="4294967295"/>
-          </FCParamGroup>
-          <FCParamGroup Name="Spreadsheet">
-            <FCText Name="AliasedCellBackgroundColor">#feff9e</FCText>
-            <FCText Name="TextColor">#000000</FCText>
-            <FCText Name="PositiveNumberColor">#000000</FCText>
-            <FCText Name="NegativeNumberColor">#000000</FCText>
-          </FCParamGroup>
-          <FCParamGroup Name="TechDraw">
-            <FCParamGroup Name="Decorations">
-              <FCUInt Name="SectionColor" Value="255"/>
-              <FCUInt Name="CenterColor" Value="255"/>
-              <FCUInt Name="VertexColor" Value="255"/>
-              <FCUInt Name="HighlightColor" Value="255"/>
-            </FCParamGroup>
-            <FCParamGroup Name="Colors">
-              <FCBool Name="ClearFace" Value="1"/>
-              <FCUInt Name="Hatch" Value="255"/>
-              <FCUInt Name="Background" Value="3553874943"/>
-              <FCUInt Name="PreSelectColor" Value="4294902015"/>
-              <FCUInt Name="HiddenColor" Value="255"/>
-              <FCUInt Name="SelectColor" Value="16711935"/>
-              <FCUInt Name="NormalColor" Value="255"/>
-              <FCUInt Name="CutSurfaceColor" Value="3553874943"/>
-              <FCUInt Name="GeomHatch" Value="255"/>
-              <FCUInt Name="FaceColor" Value="4294967295"/>
-            </FCParamGroup>
-          </FCParamGroup>
-        </FCParamGroup>
-        <FCParamGroup Name="OutputWindow">
-          <FCUInt Name="colorText" Value="255"/>
-          <FCUInt Name="colorLogging" Value="65535"/>
-          <FCUInt Name="colorWarning" Value="4289331455"/>
-          <FCUInt Name="colorError" Value="4278190335"/>
-        </FCParamGroup>
-        <FCParamGroup Name="Editor">
-          <FCUInt Name="Text" Value="0"/>
-          <FCUInt Name="Bookmark" Value="16776960"/>
-          <FCUInt Name="Breakpoint" Value="4278190080"/>
-          <FCUInt Name="Keyword" Value="65280"/>
-          <FCUInt Name="Comment" Value="11141120"/>
-          <FCUInt Name="Block comment" Value="2694882304"/>
-          <FCUInt Name="Number" Value="65280"/>
-          <FCUInt Name="String" Value="4278190080"/>
-          <FCUInt Name="Character" Value="4278190080"/>
-          <FCUInt Name="Class name" Value="4289331200"/>
-          <FCUInt Name="Define name" Value="4289331200"/>
-          <FCUInt Name="Operator" Value="2694882304"/>
-          <FCUInt Name="Python output" Value="2863300352"/>
-          <FCUInt Name="Python error" Value="4278190080"/>
-          <FCUInt Name="Current line highlight" Value="3772833792"/>
-        </FCParamGroup>
-        <FCParamGroup Name="View">
-          <FCUInt Name="SketchEdgeColor" Value="4294967295"/>
-          <FCUInt Name="SketchVertexColor" Value="4294967295"/>
-          <FCUInt Name="EditedEdgeColor" Value="4294967295"/>
-          <FCUInt Name="EditedVertexColor" Value="4280680703"/>
-          <FCUInt Name="ConstructionColor" Value="56575"/>
-          <FCUInt Name="ExternalColor" Value="3425924095"/>
-          <FCUInt Name="InvalidSketchColor" Value="4285333759"/>
-          <FCUInt Name="FullyConstrainedColor" Value="16711935"/>
-          <FCUInt Name="InternalAlignedGeoColor" Value="2998042623"/>
-          <FCUInt Name="FullyConstraintElementColor" Value="2161156351"/>
-          <FCUInt Name="FullyConstraintConstructionElementColor" Value="2410282495"/>
-          <FCUInt Name="FullyConstraintInternalAlignmentColor" Value="3739142399"/>
-          <FCUInt Name="FullyConstraintConstructionPointColor" Value="4287987967"/>
-          <FCUInt Name="ConstrainedIcoColor" Value="4280680703"/>
-          <FCUInt Name="NonDrivingConstrDimColor" Value="2555903"/>
-          <FCUInt Name="ConstrainedDimColor" Value="4280680703"/>
-          <FCUInt Name="ExprBasedConstrDimColor" Value="4286523135"/>
-          <FCUInt Name="DeactivatedConstrDimColor" Value="2139062271"/>
-          <FCUInt Name="CursorTextColor" Value="65535"/>
-          <FCUInt Name="CursorCrosshairColor" Value="4294967295"/>
-          <FCUInt Name="CreateLineColor" Value="3435973887"/>
-          <FCBool Name="Simple" Value="0"/>
-          <FCBool Name="Gradient" Value="1"/>
-          <FCBool Name="RadialGradient" Value="0"/>
-          <FCBool Name="UseBackgroundColorMid" Value="0"/>
-          <FCBool Name="RandomColor" Value="0"/>
-          <FCUInt Name="BacklightColor" Value="4294967295"/>
-          <FCUInt Name="BackgroundColor" Value="336897023"/>
-          <FCUInt Name="BackgroundColor2" Value="859006463"/>
-          <FCUInt Name="BackgroundColor3" Value="2543299327"/>
-          <FCUInt Name="BackgroundColor4" Value="1869583359"/>
-          <FCUInt Name="HighlightColor" Value="3789624575"/>
-          <FCUInt Name="SelectionColor" Value="481107199"/>
-          <FCUInt Name="DefaultShapeColor" Value="3435980543"/>
-        </FCParamGroup>
-        <FCParamGroup Name="TreeView">
-          <FCUInt Name="TreeEditColor" Value="563609599"/>
-          <FCUInt Name="TreeActiveColor" Value="1538528255"/>
         </FCParamGroup>
         <FCParamGroup Name="MainWindow">
-          <FCBool Name="TiledBackground" Value="0"/>
-          <FCText Name="StyleSheet"></FCText>
+          <FCText Name="Theme">FreeCAD Classic</FCText>
           <FCText Name="OverlayActiveStyleSheet">Light Theme + Dark Background.qss</FCText>
         </FCParamGroup>
       </FCParamGroup>
     </FCParamGroup>
   </FCParamGroup>
-
 </FCParameters>
diff --git a/src/Gui/PreferencePacks/FreeCAD Classic/post.FCMacro b/src/Gui/PreferencePacks/FreeCAD Classic/post.FCMacro
index b74390d66d..37b1e1b4aa 100644
--- a/src/Gui/PreferencePacks/FreeCAD Classic/post.FCMacro	
+++ b/src/Gui/PreferencePacks/FreeCAD Classic/post.FCMacro	
@@ -6,3 +6,208 @@ editorPrefs.RemInt("Text")
 
 appPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/General")
 appPrefs.RemString("QtStyle")
+
+# Need to remove any of the most common color settings created by other themes
+
+themesPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Themes")
+themesPrefs.RemUnsigned("ThemeAccentColor1")
+themesPrefs.RemUnsigned("ThemeAccentColor2")
+themesPrefs.RemUnsigned("ThemeAccentColor3")
+
+archPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Arch")
+archPrefs.RemUnsigned("WallColor")
+archPrefs.RemUnsigned("StructureColor")
+archPrefs.RemUnsigned("RebarColor")
+archPrefs.RemUnsigned("WindowColor")
+archPrefs.RemUnsigned("WindowGlassColor")
+archPrefs.RemUnsigned("PanelColor")
+archPrefs.RemUnsigned("ColorHelpers")
+archPrefs.RemUnsigned("defaultSpaceColor")
+
+draftPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Draft")
+draftPrefs.RemUnsigned("constructioncolor")
+draftPrefs.RemUnsigned("gridColor")
+draftPrefs.RemUnsigned("snapcolor")
+draftPrefs.RemUnsigned("color")
+draftPrefs.RemUnsigned("DefaultAnnoLineColor")
+
+techdrawDecPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/TechDraw/Decorations")
+techdrawDecPrefs.RemUnsigned("SectionColor")
+techdrawDecPrefs.RemUnsigned("CenterColor")
+techdrawDecPrefs.RemUnsigned("VertexColor")
+techdrawDecPrefs.RemUnsigned("HighlightColor")
+
+techdrawColorPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/TechDraw/Colors")
+techdrawColorPrefs.RemUnsigned("Background")
+techdrawColorPrefs.RemUnsigned("PreSelectColor")
+techdrawColorPrefs.RemUnsigned("HiddenColor")
+techdrawColorPrefs.RemUnsigned("SelectColor")
+techdrawColorPrefs.RemUnsigned("NormalColor")
+techdrawColorPrefs.RemUnsigned("CutSurfaceColor")
+techdrawColorPrefs.RemUnsigned("FaceColor")
+techdrawColorPrefs.RemUnsigned("gridColor")
+techdrawColorPrefs.RemUnsigned("PageColor")
+techdrawColorPrefs.RemUnsigned("LightTextColor")
+techdrawColorPrefs.RemUnsigned("TemplateUnderlineColor")
+
+techdrawDimsPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/TechDraw/Dimensions")
+techdrawDimsPrefs.RemUnsigned("Color")
+
+techdrawMarkupsPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/TechDraw/Markups")
+techdrawMarkupsPrefs.RemUnsigned("Color")
+
+pathPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Path")
+pathPrefs.RemUnsigned("DefaultNormalPathColor")
+pathPrefs.RemUnsigned("DefaultRapidPathColor")
+pathPrefs.RemUnsigned("DefaultPathMarkerColor")
+pathPrefs.RemUnsigned("DefaultProbePathColor")
+pathPrefs.RemUnsigned("DefaultHighlightPathColor")
+pathPrefs.RemUnsigned("DefaultBBoxSelectionColor")
+pathPrefs.RemUnsigned("DefaultBBoxNormalColor")
+
+camPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/CAM")
+camPrefs.RemUnsigned("DefaultNormalPathColor")
+camPrefs.RemUnsigned("DefaultRapidPathColor")
+camPrefs.RemUnsigned("DefaultPathMarkerColor")
+camPrefs.RemUnsigned("DefaultProbePathColor")
+camPrefs.RemUnsigned("DefaultHighlightPathColor")
+camPrefs.RemUnsigned("DefaultBBoxSelectionColor")
+camPrefs.RemUnsigned("DefaultBBoxNormalColor")
+
+partPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Part")
+partPrefs.RemUnsigned("Dimensions3dColor")
+partPrefs.RemUnsigned("DimensionsAngularColor")
+partPrefs.RemUnsigned("DimensionsDeltaColor")
+partPrefs.RemFloat("MeshAngularDeflection")
+
+measurePrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Measure/Appearance")
+measurePrefs.RemBool("DefaultMirror")
+measurePrefs.RemFloat("DefaultDistFactor")
+measurePrefs.RemInt("DefaultFontSize")
+measurePrefs.RemUnsigned("DefaultTextColor")
+measurePrefs.RemUnsigned("DefaultLineColor")
+measurePrefs.RemUnsigned("DefaultTextBackgroundColor")
+
+meshPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Mesh")
+meshPrefs.RemUnsigned("MeshColor")
+meshPrefs.RemUnsigned("LineColor")
+meshPrefs.RemUnsigned("BackfaceColor")
+
+sketcherGenPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Sketcher/General")
+sketcherGenPrefs.RemUnsigned("GridLineColor")
+
+sketcherViewPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Sketcher/View")
+sketcherViewPrefs.RemInt("EdgeWidth")
+sketcherViewPrefs.RemInt("ConstructionWidth")
+sketcherViewPrefs.RemInt("InternalWidth")
+sketcherViewPrefs.RemInt("ExternalWidth")
+sketcherViewPrefs.RemInt("EdgePattern")
+sketcherViewPrefs.RemInt("ConstructionPattern")
+sketcherViewPrefs.RemInt("InternalPattern")
+sketcherViewPrefs.RemInt("ExternalPattern")
+sketcherViewPrefs.RemUnsigned("BoundingBoxColor")
+
+sketcherPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Sketcher")
+sketcherPrefs.RemBool("AutoRemoveRedundants")
+
+pdPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/PartDesign")
+pdPrefs.RemBool("RefineModel")
+
+spreadsheetPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Mod/Spreadsheet")
+spreadsheetPrefs.RemString("AliasedCellBackgroundColor")
+spreadsheetPrefs.RemString("TextColor")
+spreadsheetPrefs.RemString("PositiveNumberColor")
+spreadsheetPrefs.RemString("NegativeNumberColor")
+
+viewPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/View")
+viewPrefs.RemUnsigned("SketchEdgeColor")
+viewPrefs.RemUnsigned("SketchVertexColor")
+viewPrefs.RemUnsigned("EditedEdgeColor")
+viewPrefs.RemUnsigned("EditedVertexColor")
+viewPrefs.RemUnsigned("ConstructionColor")
+viewPrefs.RemUnsigned("ExternalColor")
+viewPrefs.RemUnsigned("InvalidSketchColor")
+viewPrefs.RemUnsigned("FullyConstrainedColor")
+viewPrefs.RemUnsigned("InternalAlignedGeoColor")
+viewPrefs.RemUnsigned("FullyConstraintElementColor")
+viewPrefs.RemUnsigned("FullyConstraintConstructionElementColor")
+viewPrefs.RemUnsigned("FullyConstraintInternalAlignmentColor")
+viewPrefs.RemUnsigned("FullyConstraintConstructionPointColor")
+viewPrefs.RemUnsigned("ConstrainedIcoColor")
+viewPrefs.RemUnsigned("NonDrivingConstrDimColor")
+viewPrefs.RemUnsigned("ConstrainedDimColor")
+viewPrefs.RemUnsigned("ExprBasedConstrDimColor")
+viewPrefs.RemUnsigned("DeactivatedConstrDimColor")
+viewPrefs.RemUnsigned("CursorTextColor")
+viewPrefs.RemUnsigned("CursorCrosshairColor")
+viewPrefs.RemUnsigned("CreateLineColor")
+viewPrefs.RemUnsigned("AnnotationTextColor")
+viewPrefs.RemBool("UseBackgroundColorMid")
+viewPrefs.RemUnsigned("BackgroundColor")
+viewPrefs.RemUnsigned("BackgroundColor2")
+viewPrefs.RemUnsigned("BackgroundColor3")
+viewPrefs.RemUnsigned("BackgroundColor4")
+viewPrefs.RemUnsigned("BacklightColor")
+viewPrefs.RemUnsigned("BoundingBoxColor")
+viewPrefs.RemUnsigned("DefaultShapeColor")
+viewPrefs.RemUnsigned("HighlightColor")
+viewPrefs.RemUnsigned("SelectionColor")
+viewPrefs.RemUnsigned("CbLabelColor")
+viewPrefs.RemUnsigned("DefaultShapeLineColor")
+viewPrefs.RemUnsigned("DefaultShapeVertexColor")
+viewPrefs.RemUnsigned("HeadlightColor")
+viewPrefs.RemUnsigned("ShadowLightColor")
+viewPrefs.RemUnsigned("ShadowGroundColor")
+viewPrefs.RemUnsigned("HiddenLineFaceColor")
+viewPrefs.RemUnsigned("HiddenLineBackground")
+viewPrefs.RemBool("EnablePreselection")
+viewPrefs.RemBool("EnableSelection")
+viewPrefs.RemInt("AntiAliasing")
+viewPrefs.RemInt("TransparentObjectRenderType")
+viewPrefs.RemInt("MarkerSize")
+viewPrefs.RemBool("CornerCoordSystem")
+viewPrefs.RemBool("UseVBO")
+viewPrefs.RemBool("EnableBacklight")
+viewPrefs.RemBool("Simple")
+viewPrefs.RemBool("Gradient")
+viewPrefs.RemBool("RadialGradient")
+viewPrefs.RemInt("DefaultShapePointSize")
+viewPrefs.RemBool("CanAbortRecompute")
+viewPrefs.RemInt("SegmentsPerGeometry")
+viewPrefs.RemFloat("PickRadius")
+viewPrefs.RemFloat("ViewScalingFactor")
+
+outputWinPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/OutputWindow")
+outputWinPrefs.RemUnsigned("colorText")
+outputWinPrefs.RemUnsigned("colorLogging")
+outputWinPrefs.RemUnsigned("colorWarning")
+outputWinPrefs.RemUnsigned("colorError")
+outputWinPrefs.RemBool("checkShowReportViewOnError")
+
+editorPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/Editor")
+editorPrefs.RemUnsigned("Text")
+editorPrefs.RemUnsigned("Bookmark")
+editorPrefs.RemUnsigned("Breakpoint")
+editorPrefs.RemUnsigned("Keyword")
+editorPrefs.RemUnsigned("Comment")
+editorPrefs.RemUnsigned("Block comment")
+editorPrefs.RemUnsigned("Number")
+editorPrefs.RemUnsigned("String")
+editorPrefs.RemUnsigned("Character")
+editorPrefs.RemUnsigned("Class name")
+editorPrefs.RemUnsigned("Define name")
+editorPrefs.RemUnsigned("Operator")
+editorPrefs.RemUnsigned("Python output")
+editorPrefs.RemUnsigned("Python error")
+editorPrefs.RemUnsigned("Current line highlight")
+
+treeviewPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/TreeView")
+treeviewPrefs.RemUnsigned("TreeEditColor")
+treeviewPrefs.RemUnsigned("TreeActiveColor")
+treeviewPrefs.RemBool("PreSelection")
+
+navcubePrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/NaviCube")
+navcubePrefs.RemUnsigned("BaseColor")
+
+mwPrefs = FreeCAD.ParamGet("User parameter:BaseApp/Preferences/MainWindow")
+mwPrefs.RemString("StyleSheet")
diff --git a/src/Gui/PreferencePacks/FreeCAD Dark/FreeCAD Dark.cfg b/src/Gui/PreferencePacks/FreeCAD Dark/FreeCAD Dark.cfg
index f1a9024b8a..8f1dbc99d4 100644
--- a/src/Gui/PreferencePacks/FreeCAD Dark/FreeCAD Dark.cfg	
+++ b/src/Gui/PreferencePacks/FreeCAD Dark/FreeCAD Dark.cfg	
@@ -177,6 +177,7 @@
         </FCParamGroup>
         <FCParamGroup Name="MainWindow">
           <FCBool Name="TiledBackground" Value="0"/>
+          <FCText Name="Theme">FreeCAD Dark</FCText>
           <FCText Name="StyleSheet">FreeCAD Dark.qss</FCText>
           <FCText Name="OverlayActiveStyleSheet">Dark Theme + Dark Background.qss</FCText>
         </FCParamGroup>
diff --git a/src/Gui/PreferencePacks/FreeCAD Light/FreeCAD Light.cfg b/src/Gui/PreferencePacks/FreeCAD Light/FreeCAD Light.cfg
index 85a3338a6d..29e1a8830f 100644
--- a/src/Gui/PreferencePacks/FreeCAD Light/FreeCAD Light.cfg	
+++ b/src/Gui/PreferencePacks/FreeCAD Light/FreeCAD Light.cfg	
@@ -207,6 +207,7 @@
           <FCUInt Name="BaseColor" Value="3505127423"/>
         </FCParamGroup>
         <FCParamGroup Name="MainWindow">
+          <FCText Name="Theme">FreeCAD Light</FCText>
           <FCText Name="StyleSheet">FreeCAD Light.qss</FCText>
           <FCText Name="OverlayActiveStyleSheet">Light Theme + Light Background.qss</FCText>
         </FCParamGroup>