Normalized attribute name in HTML

Add prefix `data-` for following attributes:
- `topbar-visible`
- `mode`
- `label-text`
- `title-succeed`

_includes/mermaid.html

@@ -33,8 +33,8 @@
 
     let initTheme = "default";
 
-    if ($("html[mode=dark]").length > 0
-      || ($("html[mode]").length == 0
+    if ($("html[data-mode=dark]").length > 0
+      || ($("html[data-mode]").length == 0
         && window.matchMedia("(prefers-color-scheme: dark)").matches ) ) {
       initTheme = "dark";
     }