That page in particular should be using archive.php, but it is likely not where you’d want to add that div.
You should have a header.php file instead where the actual header gets added – that way you would have this div on every page and not just your archives. You would then hide the div with css, using a media query, on screensizes you don’t want it to display
.your-div {
@media ('min-width: 768px') { display: none; }
}
That should suffice to keep it off anything larger than a tablet, but you can decide what size you’d like.
If you’re in doubt of where to look, see if you can search for where the masthead or site-branding elements are added since those are in your header element and about where you’d want to place this div
I have a sticky header and I dont want this new DIV stays in the header. So I cant see the right place. Besides I dont know how to put the breadcrumbs trail inside this DIV because up to now I used a widget to display the beadcrumbs…
I tryed this test code in my archive.php
<div class="breadcrumbs"><p><?php echo "Hello World!";
?></p>
</div>
I dont know how to put order trhrow some CSS, here is how I see the page: https://ibb.co/FbzxgHYc , “Hello word!” is visible only in the mobile version, I suppose because on the desktop PC is now under the sticky header. I suppose I should armonize this new DIV with the others..First I should work on the DIV dimension: all the page long, flexible. Any advice?