The reason you don’t see a responsive template is because media queries look like this

@media only screen and (max-device-width: 480px)

while on my demo sites for I use

@media only screen and (max-width: 480px)

This is required that only devices with a max device width of 480 pixels use the responsive feature

To allow media queries only on that devices (which they are made for) and helps to get rid of unexpected results in Thunderbird and Apple mail.

You can remove the “device” from the media query to see how it looks in the browser