full width header in the theme BootFrame- Core

Hi, I have a wordpress page build on BootFrame-Core
https://tiukka.pl/tiukka_robocza/

And I have a header picture there. I want to make that picture ful width, but nothing I change in CSS helps me achieve my goal.

There is a line, I can see when I examine css in Chrome that says `container, .smartlib-content-section, .smartlib-full-strech-section .panel-row-style {
width: 1278px;
}
`

That I cant find in my CSS stylesheet in wordpress. I want it as well to be aligned to the top of the navigation bar, but it doesnt work in Mozilla, but works in Chrome. Please help me!