Background Header Idyllic Theme

Hi everybody,

I am French so I apologize for my quite bad English…

I have a problem with my header. I put an image in the footer (it’s ok) and I just wanted to put the same image in the header.
My problem is that in the footer, the picture is considered as a background, whereas in my header it’s just a picture so it doesn’t take all the screen when I zoom.

It’s a tool from my theme (Idyllic) and I don’t know which file (.css ? .php ?) I have to modify to put background instead of img src.

Here is the line code about my img (the line is veryyyy long and I don’t really know why) :

<header id="masthead" class="site-header ">
	<div class="header-wrap">
			<div id="wp-custom-header" class="wp-custom-header"><img src="https://www.v-lab.fr/wp-content/uploads/2018/04/cropped-basdepagevlab-1-3.png" width="1644" height="134" alt="V-Lab : Laboratoire de développements et analyses chimiques" srcset="https://i1.wp.com/www.v-lab.fr/wp-content/uploads/2018/04/cropped-basdepagevlab-1-3.png?w=1644 1644w, https://i1.wp.com/www.v-lab.fr/wp-content/uploads/2018/04/cropped-basdepagevlab-1-3.png?resize=300%2C24 300w, https://i1.wp.com/www.v-lab.fr/wp-content/uploads/2018/04/cropped-basdepagevlab-1-3.png?resize=768%2C63 768w, https://i1.wp.com/www.v-lab.fr/wp-content/uploads/2018/04/cropped-basdepagevlab-1-3.png?resize=1024%2C83 1024w, https://i1.wp.com/www.v-lab.fr/wp-content/uploads/2018/04/cropped-basdepagevlab-1-3.png?w=1580 1580w" sizes="(max-width: 1644px) 100vw, 1644px" /></div>		<!-- Top Header============================================= -->
		<div class="top-header">
						<div class="top-bar">
				<div class="wrap">

Thanks for your help !

Laura

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