fix css help overlay css conflict

css/reveal.scss

@@ -1640,22 +1640,23 @@ $controlsArrowAngleActive: 36deg;
 	margin-top: 0;
 }
 
-.r-overlay-help-content table {
+/* Specificity battle with reveal.js theme table styles */
+.r-overlay-help .r-overlay-help-content table {
 	border: 1px solid #fff;
 	border-collapse: collapse;
 	font-size: 16px;
 	text-align: left;
 }
 
-.r-overlay-help-content table th,
-.r-overlay-help-content table td {
+.r-overlay-help .r-overlay-help-content table th,
+.r-overlay-help .r-overlay-help-content table td {
 	width: 240px;
 	padding: 14px;
 	border: 1px solid #fff;
 	vertical-align: middle;
 }
 
-.r-overlay-help-content table th {
+.r-overlay-help .r-overlay-help-content table th {
 	padding-top: 20px;
 	padding-bottom: 20px;
 }