image background instead of button for dropdown - css

Question

I already have a dropdown with the following code:
note: class='bg_r' is in CSS for the background image (url) globe
<span class="bg_r">
Language: <a id="Lang" href="#">DropUp▲</a>
</span>
<div id="language_menu" class="lang_switch_panel">
<div class="lang_switch">
<ul>
<li>Action</li>
<li>Action</li>
<li>Action</li>
</ul>
</div>
</div>
The output for above code is as shown in figure 1 below:
Now, I'm doing similar to that(above figure) using bootstrap 4.But i'm not able to override the button style using background image.Instead of button type I replaced with anchor tag but of no use(its wrong method but i tried).
Following is the code I tried so far:
<span class="bg_r">
Language:
<button type="button" class="btn btn-sm dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropup
</button>
</span>
<!--<span class="bg_r">Language:
<a type="button" class="btn btn-sm dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropup
</a>
</span>-->
<div class="dropdown-menu">
<!-- Dropdown menu links -->
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Action</a>
</div>
The output for the code using bootstrap is as shown in figure 2 below:
How can I override button type with (background) image to get output similar to figure 1?
Thanks in advance.

Answer 1

Add btn-link class to button
Additionally add these styles to center align it
.bg_r {
background-color: aqua;
display: inline-flex;
align-items: center;
}
or add these 2 classes d-inline-flex align-items-center to bg_r span
.bg_r {
background-color: aqua;
}
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css" integrity="sha384-9gVQ4dYFwwWSjIDZnLEWnxCjeSWFphJiwGPXr1jddIhOegiu1FwO5qRGvFXOdJZ4" crossorigin="anonymous">
<span class="bg_r d-inline-flex align-items-center p-1">
Language:
<button class="btn btn-sm btn-link dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropup
</button>
</span>
<div class="dropdown-menu">
<!-- Dropdown menu links -->
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Action</a>
</div>
You can also use bg-transparent on the button that will remove the background-color from button, but will not remove the focus styles when you click on the button ! So preferably add btn-link class to it only.

Answer 2

The above answer works, or you can also replace this line
<button type="button" class="btn btn-sm dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropup</button>
by
Dropup