To prevent the logo from resizing, change the height to 76px in your CSS around line 1239 –
.header-image .light .site-title > a {
height: 56px;
}
To remove the background on the sticky menu, look in your CSS around line 1178 –
.site-header.light {
background-color: #000;
padding-top: 0;
}
Let me know if that helps…..or if you need any assistance making these adjustments.