add notification of flash message button in header

src/component/Header/MenuActionListItem/Notification.jsx

+import React from 'react'
+import PropTypes from 'prop-types'
+
+const Notification = props => {
+  return (
+    <li className='header__menu__rightside__itemnotification'>
+      <div className='header__menu__rightside__itemnotification__timeline dropdown'>
+        <button
+          type='button'
+          className='timeline__btnnotif btnnavbar btn btn-secondary dropdown-toggle'
+          id='headerNotificationBtn'
+          data-toggle='dropdown'
+          aria-haspopup='true'
+          aria-expanded='false'
+        >
+          Notification
+        </button>
+        <div className='timeline__subdropdown dropdown-menu' aria-labelledby='headerDropdownMenuButton'>
+          <div className='timeline__subdropdown__text dropdown-item' >
+            Conversation archivé
+          </div>
+          <div className='timeline__subdropdown__text dropdown-item' >
+            Fichier supprimé
+          </div>
+        </div>
+      </div>
+    </li>
+  )
+}
+export default Notification

src/container/Header.jsx

 import MenuActionListItemDropdownLang from '../component/Header/MenuActionListItem/DropdownLang.jsx'
 import MenuActionListItemHelp from '../component/Header/MenuActionListItem/Help.jsx'
 import MenuActionListItemMenuProfil from '../component/Header/MenuActionListItem/MenuProfil.jsx'
+import MenuActionListItemNotification from '../component/Header/MenuActionListItem/Notification.jsx'
 import logoHeader from '../img/logo-tracim.png'
 import {
   newFlashMessage,
                 user={user}
                 onClickLogout={this.handleClickLogout}
               />
+
+              <MenuActionListItemNotification />
             </ul>
 
           </div>

src/css/Header.styl

 .header
   position fixed
   width 100%
-  box-shadow shadow-bottom
+  border-bottom 1px solid grey
   z-index 5
   &__logo
     &__img
             color darkGrey
       &__itemprofil
         .profilgroup
+          margin-right 30px
           &__name
             border 0
             padding 0 5px
             .setting__link
               padding 10px
               color fontColor
+      &__itemnotification
+        &__timeline
+          margin-right 30px
+          .timeline
+            &__btnnotif
+              color darkGrey
+              &::after
+                margin-left 15px
+            &__subdropdown
+              padding 0
+              left inherit
+              right 0
+              cursor pointer
+              &__text
+                padding 10px;
+
 
 @media (min-width: min-lg) and (max-width: max-lg)
   .header