If you have too many menu items and the menu gets too long, then it won’t fit with the logo area. The entire header width area is 1140px and if the logo and widget area are too wide then the widget area will fall off to the side.
You can decrease the logo area to as low as 334px (due to the size of your logo) and that will add a little bit of space for another menu item –
.title-area {
font-family: 'Oswald', Helvetica, Arial, sans-serif;
font-weight: 700;
float: left;
padding: 0;
padding: 0;
width: 334px;
}
Keep in mind, eventually if you add too many links to your menu, the entire menu will not fit on the same line as the logo. They are both div containers.