Hi again,
I checked your site and the issue you’re having is due to the custom header customization i.e logo shrinking effect as the height of the header is calculated initially including your initial logo height but you’re changing the height of the logo on scroll which is disturbing the layout. As Christian suggested above that It would be best that you use Pro for this project so you can configure different header setups. Pro was built to accommodate users’ demand for a flexible header layout, in this case you’ll need custom Javascript and CSS to fix the disturbed layout which cannot be a good solution and can be the cause of potential issues in future.
As a temporary solution you can add the following code in the Theme Options > JS:
function stop_jumps() {
jQuery('header.masthead').css('height', jQuery('.x-topbar').height() + jQuery('.x-navbar').height());
}
jQuery(document).ready(function(){
stop_jumps();
});
jQuery(window).resize(function(){
stop_jumps();
});
As you see it requires custom development and it serves as a guide only so we’ll not be able to support any issue arise from the above customization.
Thank you for understanding!