How to display an image when hovering over its title in a View? In my style sheet (which does seem to be loaded), I have

.snhover_img a { position:relative; }
.snhover_img a span { position:absolute; display:none; z-index:99; }
.snhover_img a:hover span {
    display: block;
    width: 350px;
}


And in the Title field of my View, I have Rewrite results as

&lt;div class="snhover_img"&gt;
      &lt;a href="#"&gt;{{ title }}&lt;span&gt;&lt;img src="/stelnews{{ field_issue_png }}"  /&gt;&lt;/span&gt;&lt;/a&gt;
&lt;/div&gt;


But I always see both the title and the image. Nothing happens on hover. 
The debugger shows. What am I doing wrong?

Note: I am thinking that the style sheet is not really loading. If not, how do I fix that?
I post as answer because I have not reach 50 reputation to post as comment.
When you debug .snhover_img a span is the style { position:absolute; display:none; z-index:99; } applied?