Yes, I meant the id #contactHeading (just a habit I guess, I avoid using ids for CSS styles).
If you give a width of 100% to the h3 #contactHeading parent container (the .footerContenu div) the overflow will go away.
.footerContenu {
width: 120rem; /* remove this */
width: 100%; /* add this */
max-width: 120rem; /* add this to constrain */
}
To make it look the same on small screens, you will then also need to adjust the width for the inputs and textarea in the 768px media query. I actually think you can just remove the width you set there and keep the one set in the 992px media query, but that is up to you.