Add basic column view

static/js/song-controls.js

@@ -53,6 +53,23 @@ controls.querySelector("#font-size-increase").addEventListener("click", () => pa
 controls.querySelector("#font-size-decrease").addEventListener("click", () => pageScale(-0.1));
 controls.querySelector("#font-size-reset").addEventListener("click", () => pageScale(0));
 
+// Column view
+const iframe = document.querySelector("iframe.song");
+
+iframe.addEventListener("load", () => {
+	const root = iframe.contentDocument.documentElement;
+
+	if (localStorage.getItem("column-view") === "on") {
+		root.classList.add("column-view");
+	}
+
+	controls
+		.querySelector("#column-view-toggle")
+		.addEventListener("click", () => {
+			const enabled = root.classList.toggle("column-view");
+			localStorage.setItem("column-view", enabled ? "on" : "off");
+		});
+});
 
 // Display the controls on JS-enabled browsers
 window.addEventListener("load", () => controls.classList.remove = "hidden");