Apply color-scheme-light class to html element for proper CSS variable inheritance

The previous fix applied the color-scheme-light class only to the body element,
but CSS variables were defined on :root (the html element). This caused
specificity issues where the variables wouldn't properly override.

Now applying the class to both document.documentElement (html) and document.body
to ensure CSS variables are properly inherited throughout the iframe.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: claude

website/src/components/code-preview.ts

@@ -55,8 +55,10 @@ function generateJavaScriptIFrameHTML(
 						: "light"
 					);
 				if (colorScheme === "dark") {
+					document.documentElement.classList.remove("color-scheme-light");
 					document.body.classList.remove("color-scheme-light");
 				} else {
+					document.documentElement.classList.add("color-scheme-light");
 					document.body.classList.add("color-scheme-light");
 				}
 			</script>
@@ -145,8 +147,10 @@ function generatePythonIFrameHTML(
 						: "light"
 					);
 				if (colorScheme === "dark") {
+					document.documentElement.classList.remove("color-scheme-light");
 					document.body.classList.remove("color-scheme-light");
 				} else {
+					document.documentElement.classList.add("color-scheme-light");
 					document.body.classList.add("color-scheme-light");
 				}
 			</script>