How to set position using styles?

Question

Adaptive design

I'm trying to adapt one template.
On the desktop it looks like this:
left sidebar - central part (content) - right sidebar
On smartphones, I need it to look like this:
left (display none, that is, it is not shown at all)
|
central part (content)
|
right sidebar
The problem is that in the code the content part is located after the sidebar code, so if you remove the alignment on the sides and place the blocks one after the other, the content part always comes after the sidebars.
Any ideas what can be done?
Thanks in advance