You did something wrong. But we cannot guess what you did wrong.
Provide a link to your site, or make a small demo using Plunkr.
I GUESS that perhaps you may not have followed the recommended document layout. Perhaps you have loaded your CSS and JS in the wrong order, or perhaps you have loaded them in the wrong place in your document. They should be loaded in <head>.
You showed part of your markup. It's of no use to diagnose your problem.
Show the ENTIRE document, including <html> <head> <body> etc.
Or MAKE A SMALL DEMO using jsFiddle or Plunkr. Don't include all of your pages and all of your markup. Just enough to demonstrate the problem. Two pages, with minimal content should be able to demo your problem.
Usually I suggest people use Plunkr for JQM. But since you are using a multi-page document (which I do NOT recommend!) you can use jsFiddle, which is a bit easier to use. (jsFiddle is not useful for making demos of JQM with multiple pages where each page is in it's own document, but can be used for multi-page document like yours.)
You should learn to use one or both of jsFiddle or Plunkr. It's the best way to make a small demo that others can try and modify, and the best way to get your questions answered. Posting bits and pieces to the forum is not a good way to get your questions answered, as then we have to play "20 Questions".
Where is the part where you load JQM (and other) JS and CSS? That's that part that matters for this problem.