Reply To: logo@2x for retina for Ally

Try changing it to .site-container .site-header instead. You’ll also need to center it since it will show up to the left by default. Here is an example –

.site-container .site-header {
	background: url(/wp-content/uploads/2014/05/logo@2x.png) no-repeat left !important;
	background-size: 250px 85px !important;
	background-position: top center !important;
}

So replace the code you have with the code above and let me know if that fixes it.