Update designing-for-MR.md

refinement

Author: Karl-Bridge-Microsoft

hub/apps/design/devices/designing-for-MR.md

@@ -116,7 +116,7 @@ When creating a UWP app that will potentially be used on a Mixed Reality platfor
 
 * Remember, gaze is not as accurate as mouse pointing. Smaller mouse targets or buttons may cause frustration for your users, so resize controls accordingly. If they are designed for touch, they will work in Mixed Reality, but you may decide to enlarge some buttons at runtime. See [Updating 2D UWP apps for Windows Mixed Reality](/windows/mixed-reality/develop/porting-apps/building-2d-apps).
 
-* The HoloLens defines the color black as the absence of light. It's simply not rendered, allowing the "real world" so show through. Your application should not use black as this would cause confusion. In a Mixed Reality headset, black is black.
+* Your application should not use black as this could cause confusion. The HoloLens defines the color black as the absence of light and is simply not rendered, allowing the "real world" to show through. In a Mixed Reality headset, black is rendered as black.
 
 * The HoloLens does not support color themes in apps, and defaults to blue to ensure the best experience for users. For more advice about selecting colors, you should consult [this topic](https://developer.microsoft.com/windows/mixed-reality/color_light_and_materials) which discusses the use of color and material in Mixed Reality designs.