Debugging on Mobile is still hard, mainly due to lack of interface, tools and device segregation (iPhone, iPad, Android Phones, Tablets etc)
Here is quick trick I use to test my site on various mobile devices by emulating the device viewport setting.
Click on the cog icon (bottom right) in developer tools to get to the following settings tab
And then change the device viewport by selecting the required User Agent.
In my case I have selected iPhone 5 for the example below