don't add "sf-hidden" class if display is already none

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

@@ -836,7 +836,11 @@ this.singlefile.lib.core = this.singlefile.lib.core || (() => {
 				const styleElement = this.doc.createElement("style");
 				styleElement.textContent = ".sf-hidden{display:none!important;}";
 				this.doc.head.appendChild(styleElement);
-				hiddenElements.forEach(element => element.classList.add("sf-hidden"));
+				hiddenElements.forEach(element => {
+					if (element.style.display != "none") {
+						element.classList.add("sf-hidden");
+					}
+				});
 			}
 			removedElements.forEach(element => element.remove());
 		}