Background question

Yes, you can first remove background of top, white one. Then change background.

To remove top background you need to remove some code in header.php
But I highly recommend you to use child themes so that changes won’t get lost if you update your themes.
https://codex.www.ads-software.com/Child_Themes

Then copy header.php from parent theme (/wp-content/themes/preference-lite/header.php) to your child theme directory (/wp-content/themes/child-theme/) and then remove following:

Remove whole code on line 37, that is:

<div id="page-top-bg" style="border-top-color: <?php echo get_theme_mod( 'page_top_border', '#595A67' ); ?>; border-bottom-color: <?php echo get_theme_mod( 'tophalf_botline', '#BCBCBC' ); ?>; background-color:<?php echo get_theme_mod( 'tophalf_bg', '#ffffff' ); ?>;"></div>

Million thanks! Just one tiny remaining question. When I finally got the background as wanted, I would like to have the “black frame” around the header image transparent. Hopefully this’s possible too?! ??

What do you mean by “black frame”? Can you please elaborate?

This is my website (under construction of course): https://jonssonqh.com/
I’m referring to the black frame (I believe it’s called showcase) around the header image… Please let me know if I need to elaborate even more.. ??

Add the following code in your child themes style.css

#showcase-wrapper {
	background: none !important;
	padding: 0 !important;
}

#showcase-wrapper .span12 {
	width: 1200px;
	margin-left: 15px;
}

A great amount of thanks!
I like how it turned out to look. ??