CSS card overlay with image and text - html

Question

I am trying to create an overlay that will cover an entire div/card. I have three cards that I want to rollover black when active. For some reason, I can't get the entire div to be selected.
HTML:
<div class="item ">
<div class="overlay">
<img src="http://placehold.it/600x350">
<h2>Title</h2>
<p> Text</p>
</div><div class="overlay"> </div>
</div>
and CSS:
.item {
padding: 0px 0;
margin: 1%;
border-radius: 2px;
flex: 1 250px;
height: auto;
text-align: center;
background: linear-gradient(0deg, #efefef, #ffffff);
}
.overlay {
position: relative;
background-color: rgba(0,0,0,0)
-webkit-transition: opacity 1s ease-in-out;
-moz-transition: opacity 1s ease-in-out;
-o-transition: opacity 1s ease-in-out;
transition: opacity 1s ease-in-out;
}
.overlay:hover {
opacity: 1;
background-color: rgba(0,0,0,1);
}
CODEPEN EXAMPLE

Answer 1

div.item has a certain size and shape. Style it as relative so that the next thing will work
Make div.overlay position:absolute - that will overlay it, but it has no size, so it will still be invisible.
Then, make div.overlay the full height of its parent (div.item).
When made visible (at :hover) it will be 100% height/width of .item, and will overlay it.
body {background-color: #C70025;}
img {width: 100%;}
#container {width:90%;margin:0 auto;display:flex;flex-wrap:wrap;
justify-content:space-between;}
.item {color:#000;padding:0px 0;margin:1%;border-radius:2px;flex:1 250px;height:auto;text-align:center;background:linear-gradient(0deg, #efefef, #ffffff);}
.item{position:relative;}
.overlay {
position:absolute;
top:0;left:0;right:0;bottom:0;
background-color: rgba(0,0,0,0);
-webkit-transition: opacity 1s ease-in-out;
-moz-transition: opacity 1s ease-in-out;
-o-transition: opacity 1s ease-in-out;
transition: opacity 1s ease-in-out;
}
.overlay:hover {
opacity: 1;
background-color: rgba(0,0,0,1);
}
<div id="container">
<div class="item ">
<img src="http://placehold.it/600x350">
<h2>Title</h2>
<p> Text</p>
<div class="overlay"> </div>
</div>
<div class="item">
<img src="http://placehold.it/600x350">
<h2> Title </h2>
<p>Text</p>
<div class="overlay"> </div>
</div>
<div class="item">
<img src="http://placehold.it/600x350">
<h2> Title </h2>
<p>Text</p>
<div class="overlay"> </div>
</div>
</div>