Allow user to pass custom CSS file

index.js

@@ -84,6 +84,22 @@ function onClosed() {
 
 function loadPlugins(win) {
 	injectCSS(win.webContents, path.join(__dirname, "youtube-music.css"));
+	// Load user CSS
+	const cssFiles = config.get("options.cssFiles");
+	if (Array.isArray(cssFiles)) {
+		cssFiles.forEach((cssFile) => {
+			fileExists(
+				cssFile,
+				() => {
+					injectCSS(win.webContents, cssFile);
+				},
+				() => {
+					console.warn(`CSS file "${cssFile}" does not exist, ignoring`);
+				}
+			);
+		});
+	}
+
 	win.webContents.once("did-finish-load", () => {
 		if (is.dev()) {
 			console.log("did finish load");

plugins/utils.js

@@ -32,9 +32,16 @@ module.exports.listenAction = (channel, callback) => {
 	return ipcMain.on(channel, callback);
 };
 
-module.exports.fileExists = (path, callbackIfExists) => {
+module.exports.fileExists = (
+	path,
+	callbackIfExists,
+	callbackIfError = undefined
+) => {
 	fs.access(path, fs.F_OK, (err) => {
 		if (err) {
+			if (callbackIfError) {
+				callbackIfError();
+			}
 			return;
 		}