I solved it and sharing the code here in case it helps anyone else.
Here is the code to reverse the side-by-side on mobile:
/* CSS FOR TABLET AND MOBILE */
@mobile: ~"only screen and (max-width: 767px)";
/* CSS FOR MOBILE */
@media @mobile {
/* Insert Code for Mobile Below This Line*/
/* ABOUT US PAGE - split section */
[data-section-id="6220100d0da5aa3524190bd5"] {
.section-background {
width: 100% !important;
margin-left: 0%;
}
.content-wrapper {
width: 45% !important;
}
display:block;
.section-background, content-wrapper {
position:relative;
}
.section-background {
height: 300px;
}
}
#block-yui_3_17_2_1_1646520366742_4113 {
margin-left: -100% !important;
}
/*Section 2*/
[data-section-id="621fed6367fab200e77fa077"] {
.section-background {
width: 100% !important;
margin-left: 0% !important;
}
.content-wrapper {
width: 45% !important;
}
display:block;
.section-background, content-wrapper {
position:relative;
}
.section-background {
height: 300px;
}
}
#block-yui_3_17_2_1_1646259535604_3825 {
margin-right: -100% !important;
}
/* Insert Code for Mobile Above This Line */
}