Hey, I'm a follower of mashable.com and like their content. Recently, was checking out their code and found a bug.
Go to mashable.com and re-size the browser to a minimum of 640px in width. The media query kicks in and the site re flows itself to the mobile ui. Clicking on the left top corner icon reveals other navigation menu options.
Now, maximize the browser or increase the width to be more than 640px. The page re flows back to its original form. But, the already visible mobile version of the navigation menu doesn't slide out giving the user with 2 navigation menus..!
To slide it out, one has to click on any of the options on this mobile version of the navigation menu or this should lose focus or execute $('.icon-reorder').trigger('click');
Pete Cashmore and team - some tweaking required here in your css.