Displaying text on mouse hovering over image - html

Question

I am trying to display a little copyright text on top of an image when the user hovers his mouse over it, using this example.
What am I missing that I do not see the text, only the fading effect?
<div class="list-group-item">
<div class="row">
<div class="col-12 col-md-4 vertical-center-col">
<img class="img-thumbnail" src="media/images/EmployeeOne.jpg" alt="">
</div>
<div class="middle">
<div class="text">Image Copyright</div>
</div>
<div class="col-12 col-md-8 mt-2 mt-md-0">
<strong>EmployeeOne</strong>
</div>
</div>
</div>
This is my css file:
.card-img-top {
min-height: 0.1px;
}
img.img-thumbnail {
border: 1px solid #e4c9c9;
width: 100%;
height: auto;
transition: 0.5s ease;
backface-visibility: hidden;
}
.middle {
transition: 0.5s ease;
opacity: 0;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
text-align: center;
}
.text {
background-color: #04aa6d;
color: white;
font-size: 16px;
padding: 16px 32px;
}
.img-thumbnail:hover {
opacity: 0.3;
}
.img-thumbnail:hover .middle {
opacity: 1;
}

Answer 1

Put your .middle div inside the same container as your image, then select it on hover by using adjacent sibling CSS selector
.card-img-top {
min-height: 0.1px;
}
img.img-thumbnail {
border: 1px solid #e4c9c9;
width: 100%;
height: auto;
transition: 0.5s ease;
backface-visibility: hidden;
}
.middle {
transition: 0.5s ease;
opacity: 0;
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
text-align: center;
z-index: 1;
pointer-events:none;
}
.text {
background-color: #04aa6d;
color: white;
font-size: 16px;
padding: 16px 32px;
}
.img-thumbnail:hover {
opacity: 0.3;
}
.img-thumbnail:hover+.middle {
opacity: 1;
}
<div class="list-group-item">
<div class="row">
<div class="col-12 col-md-4 vertical-center-col">
<img class="img-thumbnail" src="https://www.gardendesign.com/pictures/images/675x529Max/site_3/helianthus-yellow-flower-pixabay_11863.jpg" alt="">
<div class="middle">
<div class="text">Image Copyright</div>
</div>
</div>
<div class="col-12 col-md-8 mt-2 mt-md-0">
<strong>Employee name</strong>
</div>
</div>
</div>