Fix styles for system notifications in HTML

DiscordChatExporter.Core/Exporting/Writers/Html/MessageGroupTemplate.cshtml

@@ -73,7 +73,9 @@
                         @{/* System notification content */}
                         @if(message.Kind == MessageKind.ChannelPinnedMessage)
                         {
-                            <span class="chatlog__system-notification"> pinned</span><span class="chatlog__system-message-reference-link chatlog__reference-link" onclick="scrollToMessage(event, '@message.Reference?.MessageId')"> a message</span><span class="chatlog__system-message"> to this channel.</span>
+                            <span class="chatlog__system-notification"> pinned</span>
+                            <span class="chatlog__system-notification-reference-link chatlog__reference-link" onclick="scrollToMessage(event, '@message.Reference?.MessageId')"> a message</span>
+                            <span class="chatlog__system-notification"> to this channel.</span>
                         }
                         else
                         {

DiscordChatExporter.Core/Exporting/Writers/Html/PreambleTemplate.cshtml

@@ -255,12 +255,12 @@
         }
 
         .chatlog__system-notification {
-            color: @Themed("rgb(150, 152, 157)", "rgb(94, 103, 114)")
+            color: @Themed("#96989d", "#5e6772")
         }
 
         .chatlog__system-notification-reference-link {
             font-weight: 500;
-            color: #ffffff
+            color: @Themed("#ffffff", "#2f3136");
         }
 
         .chatlog__system-notification-icon {