message: explain negative margin
diff: @@ -17,7 +17,10 @@ limitations under the License.
  .mx_MessageEditor {
  border-radius: 4px;
  padding: 3px;
  - margin: -7px -10px -5px -10px; // from fiddling around in inspector
  + // this is to try not make the text move but still have some
  + // padding around and in the editor.
  + // Actual values from fiddling around in inspector
  + margin: -7px -10px -5px -10px;
  .mx_MessageEditor_editor {
  border-radius: 4px;
  