Determine which devices you want to support and then add a stylesheet with something along these lines:
/* =Responsive Structure
----------------------------------------------- */
@media (max-width: 800px) {
/* Smaller Resolution Desktops and Laptops */
[...]
}
@media (max-width: 650px) {
/* Smaller devices */
[...]
}
@media (max-width: 450px) {
/* Even Smaller devices */
[...]
}
@media only screen and (min-device-width: 320px) and (max-device-width: 480px) {
/* Even Smaller devices */
[...]
}
It’s easiest to test if they go in descending order. more example media queries here:
http://css-tricks.com/snippets/css/media-queries-for-standard-devices/