When working with SharePoint 2013 master pages in the design manager, the master page is designed utilizing an HTML file. This HTML file contains commented out markup representing the code necessary for the .NET framework to render the page.
Recently while working with the HTML file in Adobe Dreamweaver, I found that some of the DIV tags that are NOT commented out are actually important in the final rendering of the page. In particular, I found that if you remove the
containers, the SharePoint-generated vertical scroll bar will disappear on the page, leaving no way to scroll up or down.
The important lesson here is that you must be diligent in selecting what you delete when designing master pages, page layouts and display templates in SharePoint 2013!