Hi,
You can just follow this code:
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.container {
position: relative;
width: 50%;
}
.image {
display: block;
width: 100%;
height: auto;
}
.overlay {
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
height: 100%;
width: 100%;
opacity: 0;
transition: .5s ease;
background-color: #008CBA;
}
.container:hover .overlay {
opacity: 1;
}
.text {
color: white;
font-size: 20px;
position: absolute;
top: 50%;
left: 50%;
-webkit-transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
transform: translate(-50%, -50%);
text-align: center;
}
</style>
</head>
<body>
<h2>Faded in Overlay</h2>
<div class="container">
<img src="img_avatar.png" alt="Avatar" class="image">
<div class="overlay">
<div class="text">Hello World</div>
</div>
</div>
</body>
</html>