Hello,
The logo size does not change from Desktop to Mobile. The entire screen is getting smaller but the logo size stays the same. You can try using a % width instead of px width so it can scale based on the container size rather than be a fixed size.
Template.CSS - Line 537
.s5_logo_module {
cursor: pointer;
float: left;
height: 57px;
margin-bottom: 6px;
margin-left: 12px;
margin-top: 25px;
width: 30%;
}