All the websites I've done with Muse appears in Chrome for desktop and mobile with a long horizontal scrollbar. Last month it happened for android, but now appears also in desktop. Please, Muse should contact Google as soon as possible, it's in not one website, it concerns all the Muse websites I've done, look at your own website at http://muse.adobe.com/
I don't see a problem at the link you posted. There is one vertical scollbar as expected on long pages. No horizontal scrollbar in either the latest Chrome or Firefox on desktop.
Even if there were something Adobe could do, Muse is EOL and no longer being developed. You're basically using Muse at your own risk. Eventually, all Muse sites will fail in one way or another. You're living on borrowed time. Start re-building your sites now before it's too late.
Nancy O'Shea, Adobe Product User & Community Professional Alt-Web Design & Publishing ~ Web : Print : Graphics : Media