[Bug] Fix conversation scroll in dashboard

app/javascript/dashboard/assets/scss/_layout.scss

@@ -6,7 +6,6 @@ body {
   margin: 0;
     -webkit-font-smoothing: antialiased;
   -moz-osx-font-smoothing: grayscale;
-  overflow: hidden;
 }
 
 .app-wrapper {
@@ -21,6 +20,8 @@ body {
 
 .app-content {
   @include flex;
+  @include full-height;
+  overflow: hidden;
 }
 
 .view-box {

app/javascript/dashboard/assets/scss/widgets/_sidemenu.scss

@@ -10,7 +10,6 @@
   @include full-height;
   @include margin(0);
   @include space-between-column;
-  overflow-x: hidden;
   width: $nav-bar-width;
   z-index: 1024 - 1;
 

app/javascript/dashboard/components/widgets/conversation/ConversationBox.vue

@@ -32,7 +32,7 @@
       />
     </div>
     <!-- No Conversation Selected -->
-    <div class="columns full-height conv-empty-state">
+    <div v-else class="columns full-height conv-empty-state">
       <!-- Loading status -->
       <woot-loading-state
         v-if="fetchingInboxes || loadingChatList"