Don't replace existing style content, only empty

Author: Karlinator

src/runtime/internal/dom.ts

@@ -155,7 +155,7 @@ export function get_root_for_style(node: Node): ShadowRoot | Document {
 }
 
 export function append_stylesheet(node: ShadowRoot | Document, style: HTMLStyleElement) {
-	style.textContent = '/* empty */';
+	style.textContent = style.textContent || '/* empty */';
 	append((node as Document).head || node, style);
 	return style.sheet as CSSStyleSheet;
 }