New featurered item of Internet Explorer 11 and Edge has been release in past few weeks. When you are using LiveAgent Live Chat on your website and also viewport function with device-width parameter in your css styles on your website. It cause than the scroller of the page will cover the content of the website.
The solution is very easy, you just need to update the CSS of your website with the following row to fix this little design problem.
body {-ms-overflow-style:scrollbar;}