Post Caurosel - I can not edit CSS

Good afternoon guys

I created a caurosel post to display on the main page of a website I'm developing in wordpress

My question is the following when I create the carousel it generates a shortcode [post-carousel id="276"] and in that way we insert it into a page. I'd like to apply an effect to an image of this carousel but I can not find its css. I would like to apply an effect by hovering over the image it displays a message

If anyone knows how it works, I am very grateful.

Thank you

/*código CSS */
    .descricao {
     background: #493a2ec7;
    color: #fff;
    text-align: center;
    height: 356px;
    position: absolute;
    top: 111px;
    display: none;
    padding: 22px 37px;
    width: 355px;
    margin: -64px;
}

.master:hover .descricao {
    display: block;
}

<h2 class="recipe"><span>Receitas</span></h2>
	<div class="col-xs-12">
		[post-carousel id="276"] 
	<div class="descricao"><span> APRENDA A FAZER </span> </div>
	</div>
	<div class="mobile-recipe">
		<hr>
	</div>

/ * CSS code * /     .description {      background: # 493a2ec7;     color: #fff;     text-align: center;     height: 356px;     position: absolute;     top: 111px;     display: none;     padding: 22px 37px;     width: 355px;     margin: -64px; }

.master: hover .descricao {     display: block; }