Sydney Pro not updating color change

Hi,
Trying change the mobile color for the header on themarketingshed.com.au but it doesnt update. Only can get the desktop version to update.

Hello there,

Background color of header bar on mobile screen requires a separate CSS code. Add this code to Appearance > Customize > Additional CSS from dashboard.

@media only screen and (max-width: 1024px) {
  .site-header {
    background-color: #ccc;
  }
}

Regards,
Kharis