mediawiki-skins-Vector/includes/templates/Navigation.mustache

{{!
  string html-navigation-heading heading for entire navigation that is
    usually hidden to screen readers
  string html-personal-menu content that appears as the first child of mw-head
  string html-navigation-left-tabs that appears inside #left-navigation (namespaces and variants)
  string html-navigation-right-tabs that appears inside #right-navigation (page actions and search)
  string html-sidebar sidebar HTML
}}
<div id="mw-navigation">
    <h2>{{{html-navigation-heading}}}</h2>
    <div id="mw-head">
        {{{html-personal-menu}}}
        <div id="left-navigation">
            {{{html-navigation-left-tabs}}}
        </div>
        <div id="right-navigation">
            {{{html-navigation-right-tabs}}}
        </div>
    </div>
    {{{html-sidebar}}}
</div>