@tutrix Hi, I want to ask question regarding this as well. Can I remove the left border? I don't want it to show. How do I do that via CSS? Thank you very much!

I've figured it out...
I added the left border + the node icon on mobile by including this code:

I also adjusted the CSS a bit by adding a margin between the node icon and the border, as well as between the block containing the title.

Adjust as needed based on your theme. On the right side, I reduced the font size and modified the calculation for the width...

@media screen and (max-width: 620px) {
#wpforo #wpforo-wrap .wpfl-2 .wpforo-forum-icon {
display: block !important;
}
}