added missing priorities

lib/single-file/single-file-core.js

@@ -920,9 +920,9 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 		}
 
 		static setBackgroundImage(element, url) {
-			element.style.setProperty("background-blend-mode", "normal");
-			element.style.setProperty("background-clip", "content-box");
-			element.style.setProperty("background-position", "center");
+			element.style.setProperty("background-blend-mode", "normal", "important");
+			element.style.setProperty("background-clip", "content-box", "important");
+			element.style.setProperty("background-position", "center", "important");
 			element.style.setProperty("background-color", "transparent", "important");
 			element.style.setProperty("background-image", url, "important");
 			element.style.setProperty("background-size", "100% 100%", "important");