fix tiny UI glitches

stylesheets/_index.scss

@@ -216,6 +216,9 @@ h4.section-toggle,
   .conversation {
     display: none;
   }
+  .placeholder {
+    height: 100%;
+  }
   .conversation:first-child {
     display: block;
   }

stylesheets/_session.scss

@@ -756,7 +756,7 @@ label {
 .react-contexify {
   z-index: 3;
   min-width: 200px;
-  box-shadow: none;
+  box-shadow:  0 10px 16px 0 rgba(0,0,0,0.2),0 6px 20px 0 rgba(0,0,0,0.19) !important;
 
   .react-contexify__item:not(.react-contexify__item--disabled):hover
     > .react-contexify__item__content {

ts/components/session/conversation/SessionConversationMessagesList.tsx

@@ -49,7 +49,7 @@ export class SessionConversationMessagesList extends React.Component<
 
     this.state = {
       isScrolledToBottom: false,
-      showScrollButton: true,
+      showScrollButton: false,
       doneInitialScroll: false,
     };
     this.renderMessage = this.renderMessage.bind(this);