Before not working as expected [duplicate] - html

Question

This question already has answers here:
Does :before not work on img elements?
(16 answers)
Closed 6 years ago.
I'm trying to put pseudo-element ::before with img but it just won't show. ( Is Bootstrap messing with it?)
I did look at other answers and tried to put content = "something" but it still won't show.
I also tried display: block too but it will still stay invisible.
Here's the HTML
<header class = "header container-fluid navbar navbar-fixed-top navbar-inverse">
<div class="container">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">Brand</a>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav navbar-right">
<li>Anime</li>
<li>Manga</li>
<li>Games</li>
<li class="dropdown">
Dropdown
<ul class="dropdown-menu">
<li>
<a data-toggle="modal" data-target="#myModal" >Log-In</a>
</li>
<li>Sign-Up</li>
<li role="separator" class="divider"></li>
<li>Watch Paralax</li>
</ul>
</li>
</ul>
</div><!-- /.navbar-collapse -->
</div><!-- /.container-fluid -->
</header><!-- end of header-->
<!-- MAIN IMAGE -->
<div class = "container">
<img class = "img-responsive main-pic" src="http://vignette4.wikia.nocookie.net/naruto/images/d/dc/Naruto's_Sage_Mode.png/revision/latest?cb=20150124180545" alt = "naruto">
</div>
Here's the CSS
img{
margin-top:70px;
border-radius:10px;
}
img::before{
content:"This is not working";
color:black;
font-size:200px;
}

Answer 1

The before and after properties don't work on img elements for most browsers. See here - Does :before not work on img elements?

Answer 2

It is the same reason in my answer of other post.
From the specification.
Authors specify the style and location of generated content with the :before and :after pseudo-elements. As their names indicate, the :before and :after pseudo-elements specify the location of content before and after an element's document tree content. The 'content' property, in conjunction with these pseudo-elements, specifies what is inserted.