Fix lightbox errors

customize.dist/src/less2/include/modals-ui-elements.less

@@ -140,6 +140,7 @@
                 }
                 pre.mermaid {
                     overflow: unset;
+                    margin-bottom: 0;
                 }
                 .cp-spinner {
                     border-color: @colortheme_logo-1;

www/common/inner/common-mediatag.js

@@ -299,9 +299,11 @@ define([
 
         show(i);
         var previous = function () {
+            if (i === 0) { return; }
             show(i - 1);
         };
         var next = function () {
+            if (i === tags.length - 1) { return; }
             show(i + 1);
         };
         $left.click(previous);