add animation for highlighted messages

stylesheets/_mentions.scss

@@ -85,10 +85,6 @@
   color: black;
 }
 
-.message-highlighted {
-  border-radius: $message-container-border-radius;
-  background-color: rgba(255, 197, 50, 0.2);
-}
 
 .module-conversation-list-item--mentioned-us {
   border-left: 4px solid $session-color-green !important;

stylesheets/_mixins.scss

@@ -28,3 +28,10 @@
     @include color-svg($svg, black);
   }
 }
+
+@keyframes highlightedMessageAnimation {
+  25%  { background-color: #00f782; }
+  50%  { background-color: #00000000; }
+  75%  { background-color: #00f782; }
+}
+

stylesheets/_session_theme.scss

@@ -87,14 +87,7 @@
 
 .message {
   &-highlighted {
-    border-radius: 0;
-
-    @at-root .light-theme #{&} {
-      background-color: $session-shade-5;
-    }
-    @at-root .dark-theme #{&} {
-      background-color: $session-color-white;
-    }
+    animation: highlightedMessageAnimation 3s ease-in-out;
   }
 
   &-selected {

stylesheets/_theme_dark.scss

@@ -906,8 +906,6 @@
     color: $color-white;
   }
 
-  // Module: Highlighted Message Body
-
   // Module: Search Results
 
   .module-search-results__conversations-header {

stylesheets/themes.scss

@@ -7,6 +7,8 @@ $accentLightTheme: #00e97b;
 $accentDarkTheme: #00f782;
 
 
+
+
 $themes: (
   light: (
     accent: $accentLightTheme,