Make Menu Switch to collapsed from 921px instead of 768px?

Hi, I would like the menu of the site to collapse into the mobile version when the screen size gets to below 921px. currently at 920px to 768px the menu appears on 2 levels. therfore i would like it to switch between full main menu as is now on full page desktop browsers to the mobile version at that 921px point.

Following recent discussion with @Michael Bissett in live chat (hopefully he can continue as he’s up-to-date on the changes)

Here is the sudgested CSS code from the live session

@media only screen and (min-width: 768px) {

.main-navigation ul {

float: none;

display: inline-block;