fixed the css

src/component/Thread.jsx

       </ul>
 
       <form className='wsContentThread__app__texteditor wsContentGeneric__texteditor'>
-        <div className='wsContentThread__app__texteditor__simpletext wsContentGeneric__texteditor__simpletext input-group'>
+        <div className='wsContentThread__app__texteditor__simpletext wsContentGeneric__texteditor__simpletext input-group d-inline-flex d-sm-inline-flex d-md-inline-flex d-lg-none'>
           <input type='text' className='wsContentThread__app__texteditor__simpletext__input wsContentGeneric__texteditor__simpletext__input form-control' placeholder='...' />
 
           <div className='wsContentThread__app__texteditor__simpletext__icon wsContentGeneric__texteditor__simpletext__icon input-group-addon'>
           </div>
         </div>
 
-        <div className='wsContentGeneric__texteditor__wysiwyg d-none d-xl-block'>
-          <textarea />
+        <div className='wsContentGeneric__texteditor__wysiwyg d-none d-lg-block'>
+          <textarea className='form-control' />
         </div>
 
-        <div className='wsContentThread__app__texteditor__submit wsContentGeneric__texteditor__submit d-xl-flex justify-content-xl-center'>
+        <div className='wsContentThread__app__texteditor__submit wsContentGeneric__texteditor__submit d-lg-flex justify-content-lg-center my-3'>
           <button type='submit' className='wsContentThread__app__texteditor__submit__btn wsContentGeneric__texteditor__submit__btn btn btn-primary'>
             Envoyer
-            <div className='wsContentThread__app__texteditor__submit__btn__icon wsContentGeneric__texteditor__submit__btn__icon'>
+            <div className='wsContentThread__app__texteditor__submit__btn__icon wsContentGeneric__texteditor__submit__btn__icon ml-3'>
               <i className='fa fa-paper-plane-o' />
             </div>
           </button>

src/css/index.styl

             border-color darkBlue
       &__submit
         &__btn
-          color darkBlue
+          display flex
+          color off-white
+          background-color darkBlue
 
 .received
   text-align right
       &__title
         display none
 
-@media (min-width: max-xs) and (max-width: max-lg)
+@media (min-width: max-xs) and (max-width: max-md)
   .wsContentThread
-    &__texteditor
-      padding 7px
-      &__simpletext
-        display inline-flex
-      &__submit
-        display inline-flex
-        width 80px
+    &__app
+      &__texteditor
+        padding 7px
+        &__simpletext
+          display inline-flex
+          width 70%
+        &__submit
+          display inline-flex
+          margin-left 30px
 
 @media (min-width: min-sm) and (max-width: max-sm)
   .wsContentThread
     width 100%
     box-shadow none
     z-index 1
-    &__texteditor
-      padding 7px
-      &__simpletext
-        display inline-flex
-        margin-right 15px
-        width 62%
-      &__submit
-        display inline-flex
-        width 80px
+    &__app
+      &__texteditor
+        padding 7px
+        &__simpletext
+          display inline-flex
+          margin-right 15px
+          width 62%
+        &__submit
+          display inline-flex