How can I change the logo in the off-canvas menu?

Hi Josef,

In general logo used in offcanas is taken from Mobile logo.
Yes, it can be overriden by Custom CSS.

In your case you can also use Dark header for Mobile view then white logo can fit both.

If you decided to use dark logo for Mobile and Offcanvas menu, maybe consider using this custom CSS

@media (max-width: 680px) {
#sp-header, #sp-header.header-sticky {
  background-color: #555;
  top: 58px !important;}
    .burger-icon > span { background-color: #eee;}
    }

and in Template Options - Basic - Logo - Mobile view - set logo height: 60px

After

small correction

background-color: #555 !important;

Update only that part.

and if you want to use it also for tablet instead of 680px value - use 860px - here:

@media (max-width: 860px) {

Now you have this way (iPad preview) on Mobile & Tablet

Ok, in that case:
DELETE all above today CSS code from your site and use only a NEW one:

@media (max-width: 860px) {
#sp-header, #sp-header.header-sticky {
  background-color: #fff;}
    #sp-logo .logo-image-phone {
  display: none !important;}
  #sp-logo .logo-image {
  display: block !important;}
    .offcanvas-active .burger-icon > span  {
  background-color: #ccc;}
}