use setProperty/getPropertyValue to set and get styles

extension/ui/bg/ui-options.js

@@ -574,7 +574,7 @@
 		document.getElementById("confirmLabel").textContent = message;
 		document.getElementById("formConfirmContainer").hidden = false;
 		confirmButton.focus();
-		document.body.style.overflowY = "hidden";
+		document.body.style.setProperty("overflow-y", "hidden");
 		return new Promise(resolve => {
 			confirmButton.onclick = event => hideAndResolve(event, true);
 			cancelButton.onclick = event => hideAndResolve(event);
@@ -587,7 +587,7 @@
 			function hideAndResolve(event, value) {
 				event.preventDefault();
 				document.getElementById("formConfirmContainer").hidden = true;
-				document.body.style.overflowY = "";
+				document.body.setProperty("overflow-y", "");
 				resolve(value);
 			}
 		});
@@ -596,7 +596,7 @@
 	async function reset() {
 		document.getElementById("formResetContainer").hidden = false;
 		resetCancelButton.focus();
-		document.body.style.overflowY = "hidden";
+		document.body.style.setProperty("overflow-y", "hidden");
 		return new Promise(resolve => {
 			resetAllButton.onclick = event => hideAndResolve(event, "all");
 			resetCurrentButton.onclick = event => hideAndResolve(event, "current");
@@ -610,7 +610,7 @@
 			function hideAndResolve(event, value) {
 				event.preventDefault();
 				document.getElementById("formResetContainer").hidden = true;
-				document.body.style.overflowY = "";
+				document.body.style.setProperty("overflow-y", "");
 				resolve(value);
 			}
 		});
@@ -621,7 +621,7 @@
 		document.getElementById("formPromptContainer").hidden = false;
 		promptInput.value = defaultValue;
 		promptInput.focus();
-		document.body.style.overflowY = "hidden";
+		document.body.style.setProperty("overflow-y", "hidden");
 		return new Promise(resolve => {
 			promptConfirmButton.onclick = event => hideAndResolve(event, promptInput.value);
 			promptCancelButton.onclick = event => hideAndResolve(event);
@@ -634,7 +634,7 @@
 			function hideAndResolve(event, value) {
 				event.preventDefault();
 				document.getElementById("formPromptContainer").hidden = true;
-				document.body.style.overflowY = "";
+				document.body.style.setProperty("overflow-y", "");
 				resolve(value);
 			}
 		});

extension/ui/content/content-ui.js

@@ -71,7 +71,7 @@ this.singlefile.ui = this.singlefile.ui || (() => {
 			const progressBarElement = document.querySelector(PROGRESS_BAR_TAGNAME);
 			if (progressBarElement && maxIndex) {
 				const width = Math.floor((index / maxIndex) * 100) + "%";
-				if (progressBarElement.style.width != width) {
+				if (progressBarElement.style.getPropertyValue("width") != width) {
 					requestAnimationFrame(() => progressBarElement.style.setProperty("width", Math.floor((index / maxIndex) * 100) + "%", "important"));
 				}
 			}

extension/ui/content/infobar.js

@@ -160,8 +160,8 @@ this.singlefile.infobar = this.singlefile.infobar || (() => {
 	}
 
 	function hideInfobar(infobarElement, linkElement, infoElement) {
-		infobarElement.style.opacity = .7;
-		infobarElement.onmouseout = () => infobarElement.style.opacity = .7;
+		infobarElement.style.setProperty("opacity", .7);
+		infobarElement.onmouseout = () => infobarElement.style.setProperty("opacity", .7);
 		infobarElement.style.setProperty("width", "24px", "important");
 		infobarElement.style.setProperty("background-color", "#737373", "important");
 		infobarElement.style.setProperty("cursor", "pointer", "important");