Thanks @bagdesaurabh69 . Indeed, I have just inspected the element and the h2 that causes the problem is in the body but is placed at the very top of the screen I think, hence the problem.
Here is the line in question: <h2 class=”screen-reader-text”>Main Navigation</h2>
Do you know what it is?
It is indeed in the body when you inspect the element but this line is below the : `<nav id=”site-navigation” class=”main-navigation” role=”navigation” itemprop=”name” aria-label=”Main Menu”> line which is linked to the menu. So it’s like the menu is in the body?
This is the “block” that is the problem :
<nav id="site-navigation" class="main-navigation" role="navigation" itemprop="name" aria-label="Main Menu">
<h2 class="screen-reader-text">Main Navigation</h2>
<div class="main-navigation-wrapper">
<button class="menu-toggle" aria-controls="header-menu" aria-expanded="false"><i class="icon-bars"></i><span class="hamburger-menu-label"></span><span class="screen-reader-text">Menu</span></button>
<ul id="header-menu" class="menu nav-menu" aria-expanded="false"><li id="menu-item-17" class="menu-item menu-item-type-custom menu-item-object-custom current-menu-item current_page_item menu-item-home menu-item-17"><a href="https://illustraworld.com/" aria-current="page">ACCUEIL</a></li>
<li id="menu-item-54" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-54"><a href="https://illustraworld.com/illustration-famille-personnalise">BOUTIQUE</a></li>
<li id="menu-item-8907" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-8907"><a href="https://illustraworld.com/portrait-dessin-personnalise">OFFRE PRO</a></li>
<li id="menu-item-55" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-55"><a href="https://illustraworld.com/a-propos">à PROPOS</a></li>
<li id="menu-item-56" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-56"><a href="https://illustraworld.com/illustration-portrait-personnalise">CONTACT</a></li>
<li class="menu-item wpmenucartli wpmenucart-display-right menu-item empty-wpmenucart" id="wpmenucartli"><a class="wpmenucart-contents empty-wpmenucart" style="display:none"> </a></li></ul> </div>
</nav>