Bootstrap 4 navbar/menu keep entry visible when collapsed - html

Question

This is a question similar to this one, but it is for Bootstrap 4.
I am not able to add right-justified entries on the BS4 navbar that stay visible both when collapsed and not collapsed. I spent one full afternoon without success.
This is my goal:
Here my current code (that works only when not collapsed):
<nav class="navbar navbar-light navbar-expand-xl border-bottom mainmenu sticky-top">
<a class="navbar-brand text-capitalize text-blur" href="/">
<img class="mr-1" src="/images/logo/favicon-32x32.png" alt="Logo">
<span class="">Portami in Pista</span>
</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#myTopMenu"
aria-controls="collapsableTopMen" aria-expanded="false" aria-label="[Menu]">
<span class="sr-only">[Menu]</span>
<span class="navbar-toggler-icon" title="[Menu]"/>
</button>
<div class="collapse navbar-collapse" id="collapsableTopMen">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="/Schools/">
<i class="fa fa-motorcycle fa-rotate-315 text-danger" aria-hidden="true"/>
<span class="text-blur-danger">PiP Reparto Corse</span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="/Tracks/">
<i class="fa fa-flag-checkered text-primary" aria-hidden="true"/>
<span>Piste</span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="/Blog/le-guide-del-giovedi/">
<i class="fa fa-mortar-board text-primary" aria-hidden="true"/>
<span>Le guide del giovedì</span>
</a>
</li>
</ul>
<ul class="navbar-nav ml-auto">
<!- START of section should be always visible -->
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownLang" role="button"
data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
<i class="famfamfam-flags it" title="Italiano"/>
<span class="d-inline d-xl-none">Italiano</span>
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdownLang">
<a class="dropdown-item" href="/AbpLocalization/ChangeCulture?cultureName=en&returnUrl=/">
<i class="famfamfam-flags gb" aria-hidden="true"/>
<span class="">English</span>
</a>
</div>
</li>
<!- END of section should be always visible -->
<li class="nav-item">
<a class="nav-link" href="/Account/Login"><i class="fa fa-sign-in"/> Log in</a>
</li>
</ul>
</div>
</nav>

Answer 1

Since you're using Bootstrap 4, this answer is more relevant to your question:
https://stackoverflow.com/a/41513784/171456 (see the last part)
The part that you always want to keep visible needs to be separate from any of the collapsible parts. Then use the order-* classes to position the items as desired:
Demo: https://codeply.com/p/ylDhhZtpiH
<nav class="navbar navbar-light navbar-expand-xl border-bottom mainmenu sticky-top justify-content-start">
<a class="navbar-brand text-capitalize text-blur" href="/">
<img class="mr-1" src="//placehold.it/32" alt="Logo">
<span class="">Portami in Pista</span>
</a>
<button class="navbar-toggler order-2 ml-1" type="button" data-toggle="collapse" data-target=".collapsable" aria-controls="collapsableTopMen" aria-expanded="false" aria-label="[Menu]">
<span class="sr-only">[Menu]</span>
<span class="navbar-toggler-icon" title="[Menu]"></span>
</button>
<!-- 1st collapse menu -->
<div class="collapse navbar-collapse collapsable flex-grow-0 flex-xl-grow-1 order-last" id="collapsableTopMen">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="/Schools/">
<i class="fa fa-motorcycle fa-rotate-315 text-danger" aria-hidden="true"></i>
<span class="text-blur-danger">PiP Reparto Corse</span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="/Tracks/">
<i class="fa fa-flag-checkered text-primary" aria-hidden="true"></i>
<span>Piste</span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="/Blog/le-guide-del-giovedi/">
<i class="fa fa-mortar-board text-primary" aria-hidden="true"></i>
<span>Le guide del giovedì</span>
</a>
</li>
</ul>
</div>
<!-- always visible portion -->
<ul class="navbar-nav order-1 order-xl-last ml-auto">
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownLang" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
<i class="fas fa-flag it" title="Italiano"></i>
<span class="d-inline d-xl-none">Italiano</span>
</a>
<div class="dropdown-menu dropdown-menu-right" aria-labelledby="navbarDropdownLang">
<a class="dropdown-item" href="#">
<i class="fas fa-flag-usa gb" aria-hidden="true"></i>
<span class="">English</span>
</a>
</div>
</li>
</ul>
<!-- 2nd collapse menu -->
<div class="collapse navbar-collapse collapsable flex-grow-0 order-last">
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link" href="/Account/Login"><i class="fa fa-sign-in"></i> Log in</a>
</li>
</ul>
</div>
</nav>
https://codeply.com/p/ylDhhZtpiH

Answer 2

I did a small important fix to the good answer from Zim.
I fixed the "always visible" portion of the menu as he did not overlap the whole menu when it was collapsed.
Adding a custom .navbar-always-overlapped class, fixed it.
<nav class="navbar navbar-light navbar-expand-lg border-bottom mainmenu sticky-top justify-content-start">
<!-- same code from Zim here>
...
<!-- always visible portion. Note the 'navbar-always-overlapped' -->
<ul class="navbar-nav navbar-always-overlapped order-1 order-lg-last ml-auto">
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownLang" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
<i class="fas fa-flag it" title="Italiano"></i>
<span class="d-inline d-lg-none">Italiano</span>
</a>
<div class="dropdown-menu dropdown-menu-right" aria-labelledby="navbarDropdownLang">
<a class="dropdown-item" href="#">
<i class="fas fa-flag-usa gb" aria-hidden="true"></i>
<span class="">English</span>
</a>
</div>
</li>
</ul>
<!-- 2nd collapse menu -->
<div class="collapse navbar-collapse collapsable flex-grow-0 order-last">
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link" href="/Account/Login"><i class="fa fa-sign-in"></i> Log in</a>
</li>
</ul>
</div>
</nav>
and the code for .navbar-always-overlapped:
.navbar-always-overlapped .dropdown-menu {
position: absolute !important;
}
See https://codeply.com/p/9deLYTGblZ