change logo on specific sites on mobile

With mobile, just change your code to this

 <style>
header#header img {
  content: url("https://static1.squarespace.com/static/6543b43f555c594c9d98c11a/t/654a3d67afd27f1206b302c7/1699364199599/studio+applaus_logo_sl_rgb_blue.png");
  }
   @media screen and (max-width:767px) {
   header#header img {
  content: url("https://static1.squarespace.com/static/6543b43f555c594c9d98c11a/t/654a3d67afd27f1206b302c7/1699364199599/studio+applaus_logo_sl_rgb_blue.png");
  }
   }
</style>

Replace url in the code with new mobile image url