Sometimes it's not possible to close the content container. The solution we are using is a bit different but prevent a overflow because of the firefox scrollbar size!
.full-width {
margin-top: 15px;
margin-bottom: 15px;
position: relative;
width: calc(100vw - 10px);
margin-left: calc(-50vw + 5px);
left: 50%;
}
Here is a example: https://jsfiddle.net/RubbelDeKatz/wvt9253q