add a background-color on the messagelist

src/css/index.styl

     width 100%
     &__messagelist
       flex 1 1 auto
+      margin 0
       padding 15px 35px
       list-style none
       overflow-y auto
+      background-color off-white
       &__item
         &__avatar
           position relative
           font-size 15px
     &__texteditor
       flex 0 1 auto
+      border-top 1px solid grey
       &__simpletext
         &__input
           &:focus