Don't replace existing style content, only empty

src/runtime/internal/dom.ts

@@ -156,7 +156,7 @@ export function get_root_for_style(node: Node): ShadowRoot | Document {
 
 export function append_empty_stylesheet(node: Node) {
 	const style_element = element('style') as HTMLStyleElement;
-	style_element.textContent = '/* empty */';
+	style_element.textContent = style_element.textContent || '/* empty */';
 	append_stylesheet(get_root_for_style(node), style_element);
 	return style_element.sheet as CSSStyleSheet;
 }