I have a problem that header problem with panel option 'push'

I have a problem that header problem with panel option 'push'

first, sorry, i can't english well.

I'm making a mobile page with using jquery mobile.
but, i can't solve problem with panel 

I set a height % for mobile full screen and set layout.
for example,
<style>
body,html
{
      height : 100%;
}
#content
{
      height : 100%;
}
#content_a
{
      height : 20%;
}
 
#content_b
{
      height : 70%;
}

#content_c
{
      height : 10%;
}

content a+b+c height is 100%. is normally work,  when data-display="overlay" . but,  
after input code '<data-role ="panel"  data-display="push">' , height % is ignored. so, height automatically resized for content length.

How can i solve this problem?