Use ‘atom-workspace-axis’ custom tag name instead of ‘div’

src/workspace-element.coffee

@@ -26,11 +26,10 @@ class WorkspaceElement extends HTMLElement
     @classList.add 'workspace'
     @setAttribute 'tabindex', -1
 
-
-    @verticalAxis = document.createElement('div')
+    @verticalAxis = document.createElement('atom-workspace-axis')
     @verticalAxis.classList.add('vertical')
 
-    @horizontalAxis = document.createElement('div')
+    @horizontalAxis = document.createElement('atom-workspace-axis')
     @horizontalAxis.classList.add('horizontal')
     @horizontalAxis.appendChild(@verticalAxis)
 

static/workspace-view.less

@@ -28,14 +28,14 @@ atom-workspace {
   background-color: @app-background-color;
   font-family: @font-family;
 
-  > .horizontal {
+  atom-workspace-axis.horizontal {
     display: -webkit-flex;
     height: 100%;
+  }
 
-    > .vertical {
-      display: -webkit-flex;
-      -webkit-flex: 1;
-      -webkit-flex-flow: column;
-    }
+  atom-workspace-axis.vertical {
+    display: -webkit-flex;
+    -webkit-flex: 1;
+    -webkit-flex-flow: column;
   }
 }