What is the size of the slider image for WordPress Twenty Fourteen theme?
WordPress Twenty Fourteen theme comes with a built in homepage slider (see tutorial on how to use). In order for the slider to look good in all browser sizes, the image needs to be at least 1038 x 576 pixels in size.
If it is smaller than that, then the desktop view when the browser window is expanded wide will reveal gaps in the layout…
even though it may look fine on the mobile view …