I would go back to the width 100% or you could try 90%: (line 2055)
.header-image .site-title a {
float: left;
min-height: 164px;
width: 100%;
}
I looked and didn’t find this bit of code at the bottom of your css. This added code shrinks your logo when viewed on small screens:
.header-image .site-title a {
background-size: contain !important;
I just tried it on your site (using Chrome) and it looked fine, centered, and sharp image.
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