http://bit.ly/get_your_divi_on
Here is a list of the main media queries used in the Divi Theme. You can use this as a helpful template for your custom CSS.
/*** Responsive Styles Large Desktop And Above ***/
@media all and (min-width: 1405px) {
}
/*** Responsive Styles Standard Desktop Only ***/
@media all and (min-width: 1100px) and (max-width: 1405px) {
}
/*** Responsive Styles Tablet And Below ***/
@media all and (max-width: 980px) {
}
/*** Responsive Styles Tablet Only ***/
@media all and (min-width: 768px) and (max-width: 980px) {
}
/*** Responsive Styles Smartphone Only ***/
@media all and (max-width: 767px) {
}
/*** Responsive Styles Smartphone Portrait ***/
@media all and (max-width: 479px) {
}