Browser device emulation doesn't work

Hi
Mobile Joomla installed and all loking good on my iPhone
but I need to restyle some aspects and need to see what the mobile version looks like in my browser (chrome or firefox) but resizing the browser to make it narrow doesnt force it to show the mobile version. Ive also tried the firefox and chome device emulators that work on all my other sites but not on the Joomla site with mobile joomla installed so is your plugin blocking that in some way?

MobileJoomla stores detected mode to cookie, so it's necessary to clear site's cookies to work with emulators.

Alternatively, use ?device= parameter to change mode:

website.com/?device=xhtml - Smartphone
website.com/?device=iphone - iPhone
website.com/?device=desktop - Desktop