Thanks esmi and WPyogi, I will create a child theme.
Rod, I activated your plug-in, and right now it’s using the images you included, but my iPhone shows header3200… shouldn’t it be showing one of the smaller images?
Also, if I already edited parts of TwentyThirteen, can I change the name of the theme in style.css and create the child theme that way, or do I have to duplicate it first so that the default theme still stays in the Themes?
Thanks Rod, I will definitely take a look at that when I get home!
