Limit content width at streched layout 1140px when resizing window

Hello,

I have following problem:
I use Highend 2.0 theme with streched layout limited 1140 px in general layout options.

When the browser window is expanded to more than approx. 1610px in width the content area is limited to a width of 1140px.
If the browser window is smaller than 1610px, e.g. 1480 px, the witdth of the content area is approx. 1270px.

I want to have a maximum width of the content area of 1140px and not more. How can I do this?

Thanks an Best Regards
Wolfgang