diff --git a/src/Ucm/Workspace/WorkspacePane.elm b/src/Ucm/Workspace/WorkspacePane.elm
index 42fd4cf..baa942b 100644
--- a/src/Ucm/Workspace/WorkspacePane.elm
+++ b/src/Ucm/Workspace/WorkspacePane.elm
@@ -15,7 +15,7 @@ import Code.ProjectDependency as ProjectDependency exposing (ProjectDependency)
 import Code.Source.SourceViewConfig as SourceViewConfig
 import Code.Syntax.SyntaxConfig as SyntaxConfig
 import Html exposing (Html, div, span, strong, text)
-import Html.Attributes exposing (class)
+import Html.Attributes exposing (class, classList)
 import Lib.HttpApi as HttpApi exposing (ApiRequest, HttpResult)
 import Lib.ScrollTo as ScrollTo
 import Lib.Util as Util
@@ -552,9 +552,9 @@ viewItem definitionSummaryTooltip item isFocused =
         |> Maybe.withDefault UI.nothing
 
 
-view : Model -> Html Msg
-view model =
-    div [ class "workspace-pane" ]
+view : Bool -> Model -> Html Msg
+view isFocused model =
+    div [ class "workspace-pane", classList [ ( "workspace-pane_focused", isFocused ) ] ]
         (model.workspaceItems
             |> WorkspaceItems.mapToList (viewItem model.definitionSummaryTooltip)
         )
diff --git a/src/Ucm/Workspace/WorkspacePanes.elm b/src/Ucm/Workspace/WorkspacePanes.elm
index 194b4d7..9e0d885 100644
--- a/src/Ucm/Workspace/WorkspacePanes.elm
+++ b/src/Ucm/Workspace/WorkspacePanes.elm
@@ -104,6 +104,38 @@ toggleRightPane model =
     { model | focusedPane = focus }
 
 
+focusRight : Model -> Model
+focusRight model =
+    let
+        focus =
+            case model.focusedPane of
+                LeftPaneFocus { rightPaneVisible } ->
+                    if rightPaneVisible then
+                        RightPaneFocus
+
+                    else
+                        model.focusedPane
+
+                _ ->
+                    model.focusedPane
+    in
+    { model | focusedPane = focus }
+
+
+focusLeft : Model -> Model
+focusLeft model =
+    let
+        focus =
+            case model.focusedPane of
+                LeftPaneFocus _ ->
+                    model.focusedPane
+
+                RightPaneFocus ->
+                    LeftPaneFocus { rightPaneVisible = True }
+    in
+    { model | focusedPane = focus }
+
+
 openDefinition : Config -> Model -> Reference -> ( Model, Cmd Msg )
 openDefinition config model ref =
     case model.focusedPane of
@@ -150,11 +182,11 @@ subscriptions model =
 view : Model -> Html Msg
 view model =
     let
-        left =
-            Html.map LeftPaneMsg (WorkspacePane.view model.left)
+        left isFocused =
+            Html.map LeftPaneMsg (WorkspacePane.view isFocused model.left)
 
-        right =
-            Html.map RightPaneMsg (WorkspacePane.view model.right)
+        right isFocused =
+            Html.map RightPaneMsg (WorkspacePane.view isFocused model.right)
 
         paneConfig =
             SplitPane.createViewConfig
@@ -165,19 +197,16 @@ view model =
 
         splitter =
             { attributes = [ class "workspace-panes_resize-handle" ]
-            , children =
-                [ div [ class "workspace-panes_left" ] []
-                , div [ class "workspace-panes_right" ] []
-                ]
+            , children = []
             }
     in
     case model.focusedPane of
         LeftPaneFocus { rightPaneVisible } ->
             if rightPaneVisible then
-                SplitPane.view paneConfig left right model.splitPane
+                div [ class "workspace-panes" ] [ SplitPane.view paneConfig (left True) (right False) model.splitPane ]
 
             else
-                left
+                div [ class "workspace-panes_single-pane" ] [ left True ]
 
         RightPaneFocus ->
-            SplitPane.view paneConfig left right model.splitPane
+            div [ class "workspace-panes" ] [ SplitPane.view paneConfig (left False) (right True) model.splitPane ]
diff --git a/src/Ucm/WorkspaceScreen.elm b/src/Ucm/WorkspaceScreen.elm
index a32d2e6..9a05163 100644
--- a/src/Ucm/WorkspaceScreen.elm
+++ b/src/Ucm/WorkspaceScreen.elm
@@ -190,6 +190,12 @@ update appContext msg model =
                 toggleSidebar =
                     ( { model_ | sidebarVisible = not model_.sidebarVisible }, Cmd.none )
 
+                focusLeft =
+                    ( { model_ | panes = WorkspacePanes.focusLeft model_.panes }, Cmd.none )
+
+                focusRight =
+                    ( { model_ | panes = WorkspacePanes.focusRight model_.panes }, Cmd.none )
+
                 ( nextModel, cmd ) =
                     case ( model_.modal, shortcut ) of
                         ( NoModal, Chord Ctrl (K _) ) ->
@@ -210,6 +216,18 @@ update appContext msg model =
                         ( NoModal, Chord Ctrl (B _) ) ->
                             toggleSidebar
 
+                        ( NoModal, Sequence (Just (W _)) ArrowLeft ) ->
+                            focusLeft
+
+                        ( NoModal, Sequence (Just (W _)) (H _) ) ->
+                            focusLeft
+
+                        ( NoModal, Sequence (Just (W _)) ArrowRight ) ->
+                            focusRight
+
+                        ( NoModal, Sequence (Just (W _)) (L _) ) ->
+                            focusRight
+
                         ( NoModal, Sequence (Just (W _)) (P _) ) ->
                             let
                                 ( switchProject, switchProjectCmd ) =
diff --git a/src/Window.elm b/src/Window.elm
index df8596b..d6dd095 100644
--- a/src/Window.elm
+++ b/src/Window.elm
@@ -482,8 +482,7 @@ view toMsg model win =
                         splitter =
                             { attributes = [ class "window-sidebar_resize-handle" ]
                             , children =
-                                [ div [ class "window-sidebar_resize-handle_sidebar-side" ] []
-                                , div [ class "window-sidebar_resize-handle_main-pane-side" ] []
+                                [ div [ class "window-sidebar_resize-handle_main-pane-side" ] []
                                 ]
                             }
 
diff --git a/src/css/ucm/workspace/workspace-card.css b/src/css/ucm/workspace/workspace-card.css
index f95adea..a911d37 100644
--- a/src/css/ucm/workspace/workspace-card.css
+++ b/src/css/ucm/workspace/workspace-card.css
@@ -10,6 +10,7 @@
   padding: 0;
   width: 100%;
   max-width: var(--c-workspace-card_width);
+  z-index: var(--layer-base);
 
   & .workspace-card_titlebar {
     display: flex;
diff --git a/src/css/ucm/workspace/workspace-pane.css b/src/css/ucm/workspace/workspace-pane.css
index 09cf3f2..864d398 100644
--- a/src/css/ucm/workspace/workspace-pane.css
+++ b/src/css/ucm/workspace/workspace-pane.css
@@ -27,4 +27,22 @@
       }
     }
   }
+
+  &:not(.workspace-pane_focused) {
+    opacity: 0.65;
+  }
+
+  /*
+   * POTENTIAL focus indicator
+  &.workspace-pane_focused::before {
+    content: " ";
+    background: linear-gradient(to bottom, var(--color-gray-darken-10), transparent);
+    height: 20rem;
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    z-index: var(--layer-beneath);
+  }
+  */
 }
diff --git a/src/css/ucm/workspace/workspace-panes.css b/src/css/ucm/workspace/workspace-panes.css
index 050f577..a0053b1 100644
--- a/src/css/ucm/workspace/workspace-panes.css
+++ b/src/css/ucm/workspace/workspace-panes.css
@@ -1,3 +1,10 @@
+.workspace-panes, .workspace-panes_single-pane {
+  display: flex;
+  flex: 1;
+  width: 100%;
+  height: 100%;
+}
+
 .workspace-panes_resize-handle {
   width: 1.5rem;
   z-index: 1;
@@ -21,3 +28,7 @@
 .workspace-panes_resize-handle:hover::before {
   background: var(--u-color_focus-border);
 }
+
+.workspace-panes .workspace-card {
+  max-width: 100% !important;
+}
diff --git a/src/css/window.css b/src/css/window.css
index 018af81..2d8464c 100644
--- a/src/css/window.css
+++ b/src/css/window.css
@@ -27,10 +27,6 @@ body:has(.window-footer) {
   font-size: var(--font-size-medium);
 }
 
-.window-content-shell:has(.window-sidebar) .window-content {
-  margin-left: -0.5rem;
-}
-
 .window-control-bar {
   height: 2.5rem;
   user-select: none;
@@ -89,27 +85,26 @@ body:has(.window-footer) {
 }
 
 .window-sidebar_resize-handle {
-  --c-window_sidebar_resize-handle_width: 1rem;
+  --c-window_sidebar_resize-handle_width: 0.5rem;
   height: 100%;
-  width: var(--c-window_sidebar_resize-handle_width);
   transition: all 0.2s;
   cursor: col-resize;
-  margin-left: -0.5rem;
-
-  & .window-sidebar_resize-handle_sidebar-side {
-    position: relative;
-    height: 100%;
-    width: calc(var(--c-window_sidebar_resize-handle_width) / 2);
-    border-right: 1px solid var(--u-color_chrome_border);
-  }
+  margin-left: 0;
+  position: relative;
+  width: 1px;
 
   & .window-sidebar_resize-handle_main-pane-side {
     height: 100%;
-    width: calc(var(--c-window_sidebar_resize-handle_width) / 2);
+    width: var(--c-window_sidebar_resize-handle_width);
+    border-left: 1px solid var(--u-color_chrome_border);
+    position: absolute;
+    z-index: var(--layer-floating-controls);
+    top: 0;
+    bottom: 0;
   }
 }
 
-.window-sidebar_resize-handle:hover .window-sidebar_resize-handle_sidebar-side {
+.window-sidebar_resize-handle:hover .window-sidebar_resize-handle_main-pane-side {
   border-color: var(--u-color_focus-border);
 }