fix(Pinning): Add left border for right container

There was a border on the left container but not on the right container;
no visual separation.

Author: c0bra

src/features/pinning/less/pinning.less

@@ -35,6 +35,39 @@
     width: @gridBorderWidth;
     background-color: darken(@headerVerticalBarColor, 15%);
   }
+
+
+  &.ui-grid-pinned-container-right .ui-grid-header-cell:first-child {
+    box-sizing: border-box;
+    border-left: @gridBorderWidth solid;
+    border-width: @gridBorderWidth;
+    border-color: darken(@headerVerticalBarColor, 15%);
+  }
+
+  &.ui-grid-pinned-container-right .ui-grid-cell:first-child {
+    box-sizing: border-box;
+    border-left: @gridBorderWidth solid;
+    border-width: @gridBorderWidth;
+    border-color: darken(@verticalBarColor, 15%);
+  }
+
+  &.ui-grid-pinned-container-right .ui-grid-header-cell:not(:first-child) .ui-grid-vertical-bar, .ui-grid-cell:not(:first-child) .ui-grid-vertical-bar {
+    width: @gridBorderWidth;
+  }
+
+  &.ui-grid-pinned-container-right .ui-grid-header-cell:not(:first-child) .ui-grid-vertical-bar {
+    background-color: @headerVerticalBarColor;
+  }
+
+  &.ui-grid-pinned-container-right .ui-grid-cell:not(:last-child) .ui-grid-vertical-bar {
+    background-color: darken(@verticalBarColor, 15%);
+  }
+
+  &.ui-grid-pinned-container-first .ui-grid-header-cell:first-child .ui-grid-vertical-bar {
+    left: -1px; // TODO(c0bra): Should this be grid width? Test column resizing with custom grid border width
+    width: @gridBorderWidth;
+    background-color: darken(@headerVerticalBarColor, 15%);
+  }
 }
 
 .ui-grid-render-container-body {