Add first pass at unsupported message and style

services/web/app/views/project/editor/review-panel.pug

@@ -235,8 +235,10 @@
 			i.fa.fa-list
 			span.rp-nav-label #{translate("overview")}
 
-	.rp-unsupported-msg
-		p UNSUPPORTED
+	.rp-unsupported-msg-wrapper
+		.rp-unsupported-msg
+			i.fa.fa-5x.fa-exclamation-triangle
+			p Track Changes is unsupported in Rich Text mode
 
 
 script(type='text/ng-template', id='changeEntryTemplate')

services/web/public/stylesheets/app/editor/review-panel.less

@@ -846,12 +846,28 @@
 		}
 	}
 
-.rp-unsupported-msg {
+.rp-unsupported-msg-wrapper {
 	display: none;
-	.rp-unsupported & {
+	.rp-size-expanded.rp-unsupported & {
+		display: block;
+	}
+
+	height: 100%;
+
+	.rp-unsupported-msg {
 		display: flex;
+		width: @review-panel-width - 40px;
+		height: 100%;
 		flex-direction: column;
-		width: @review-panel-width;
+		justify-content: center;
+		align-items: center;
+		margin: 0 auto;
+		text-align: center;
+
+		p {
+			font-size: 1.3em;
+			margin-top: 13px;
+		}
 	}
 }