eretu12

I would suggest to check your theme settings to see if you can disable the theme’s sticky functionality. Perhaps there’s a way to set the logo image larger (it looks like the theme uses a small logo and a large one). or you can as well try this
From what I can see when I check your site, the logo is made smaller due to the theme’s default functionality. Basically, the theme already makes your header sticky (and controls the size of your logo), so at this point, you’re using two different methods on the same header.

You can override this by adding this to your CSS:

.top_panel_fixed .top_panel_wrap .logo_fixed {
display:none;
}

.top_panel_fixed .top_panel_wrap .logo_main {
display:block;
}