replace slashes when background save is disabled

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

@@ -829,6 +829,9 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 			filename = await DomUtil.evalTemplateVariable(filename, "digest-sha-512", async () => DOM.digest("SHA-512", content));
 			filename = filename.replace(/[~\\?%*:|"<>\x00-\x1f\x7F]+/g, "_"); // eslint-disable-line no-control-regex
 			filename = filename.replace(/\.\.\//g, "").replace(/^\/+/, "").replace(/\/+/g, "/").replace(/\/$/, "");
+			if (!options.backgroundSave) {
+				filename = filename.replace(/\//g, "_");
+			}
 			if (filename.length > 192) {
 				const extensionMatch = filename.match(/(\.[^.]{3,4})$/);
 				const extension = extensionMatch && extensionMatch[0] && extensionMatch[0].length > 1 ? extensionMatch[0] : "";