I see that there are no responsive parameters available for site width and site max width here in the sitewide settings:

Is this possible to add? Because that would be really helpful instead of having to use css for each breakpoint like to target the content and header:
@media (max-width: 1200px) {
.x-container.width {
width: 90%;
}
.x-bar-content.x-container.width {
flex-basis: 90%;
}
}