fix(theme-common): ThemedComponent should display something when JS is disabled (#9243)

packages/docusaurus-theme-common/src/components/ThemedComponent/styles.module.css

@@ -16,3 +16,11 @@
 [data-theme='dark'] .themedComponent--dark {
   display: initial;
 }
+
+/*
+JS disabled??? Show light version by default => better than showing nothing
+TODO bad, but we currently always show light mode when there's no data-theme
+ */
+html:not([data-theme]) .themedComponent--light {
+  display: initial;
+}