I’m a step nearer. I used css to control the state before it is clicked:
.fa-navicon:before {
font-family: 'font awesome 5 free';
content:"\f107";
font-weight:900;
}
I tried the following to target the toggle icon after it’s clicked, but it doesn’t appear to work:
.elementor-menu-toggle.eltoggled-on .fa-navicon:before {
font-family: 'font awesome 5 free';
content:"\f107";
font-weight:900;
}