message: Fix missing background color in GroupFilterPanel
diff: @@ -14,7 +14,14 @@ See the License for the specific language governing permissions and
  limitations under the License.
  */
  +.mx_MatrixChat--with-avatar {
  .mx_GroupFilterPanel {
  + background-color: transparent;
  + }
  +}
  +
  +.mx_GroupFilterPanel {
  + background-color: $groupFilterPanel-bg-color;
  flex: 1;
  cursor: pointer;
  position: relative;
  