I have encountered an unpleasant gui change in the new version Visual Studio Express for Web 2013.
By default, the HTM and HTML files are opened with pure HTML Editor which does not display the Design, Split and Source buttons at the bottom of the screen and you get just the pure source HTML code view.
How to change the default? Simply click the following:
Tools - Options - Text Editor - File Extensions
and on the right pane type the HTM and HTML extensions and associate them with the HTML (Web Forms) Editor instead of their default.