Изменено
.card-body-topic-align{
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
height: 100%;
width:100%;
}
на
.card-body-topic-align{
position: absolute;
top: 0%;
left: 0%;
/* transform: translate(-50%, -50%); */
height: 100%;
width:100%;
}
и удалено :
@media only screen and (min-width:992px){
.card-body-topic-align{
transform: translate(-50%, -50%);
}
}
ваше преобразование не смогло покрыть все области на всех размерах экрана ... должно быть какое-то округление, которое препятствует покрытию всех пикселей; Демонстрация ниже работала для меня на вашем примере с ручкой :
html {
font-size: 62.5%;
}
.card-deck {
margin-top: 50px
}
.card-container {
max-width: 1400px;
width: 95%;
}
.card-body {
max-width: 250px;
padding-left: 10px;
margin-top: -2px;
cursor: pointer;
transition: .3s;
-webkit-transition: .3s;
}
.card-deck {
display: flex;
overflow: auto;
}
img.card-img-top {
max-width: 250px;
}
.card {
margin-right: 16px;
border: none;
flex: 0 0 auto;
}
.bkg-color {
background-color: purple;
}
.card-block-img {
margin-bottom: 1.75rem;
margin-top: 3.2rem;
}
.card-block-txt {
margin-bottom: 2.4rem;
}
.card-sub-topic-title {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
width: 80%;
font-family: 'Lora', "Georgia", "Times New Roman";
color: #fff;
font-size: 2.4rem;
line-height: 3.4rem;
}
.card-body.card-body-topic.card-body-topic-align {
margin-top: 0px;
}
.card-topic {
border: 0px !important;
box-shadow: -8px 8px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
margin-left: 10px;
}
.card-body-topic {
background-color: #0000009e;
border: 0px !important;
}
.card-topic.card .card-body:hover {
background-color: #000000c7;
border: 0px !important;
}
.card-body-topic-align {
position: absolute;
top: 0%;
left: 0%;
/* transform: translate(-50%, -50%); */
height: 100%;
width: 100%;
}
@media only screen and (min-width: 768px) {
.card-deck {
display: flex;
padding-bottom: 75px;
}
.card-body {
min-width: 350px;
}
img.card-img-top {
min-width: 350px;
}
.card-block-img {
margin-bottom: 6rem;
}
@media only screen and (min-width:992px) {
.card-deck .card {
margin-right: 15px;
}
.card-body {
min-width: 100%;
}
img.card-img-top {
min-width: 100%;
}
.topic-container {
padding-top: 95px;
margin: 6.4rem 0 10.4rem 0;
}
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css">
<div class="card-container mx-auto">
<div class="card-deck flex-row flex-nowrap card-deck-topic bkg-color">
<div class="card card-topic">
<a href="#" class="topic-card-box">
<img src="https://images-na.ssl-images-amazon.com/images/I/91V8Nhn8CDL._SL1500_.jpg" class="card-img-top" />
<div class="card-body card-body-topic card-body-topic-align">
<p class="card-sub card-sub-topic-title">Title Here<span class="line-two">Second Line of Text</span></p>
</div>
</a>
</div>
<div class="card card-topic">
<a href="#" class="topic-card-box">
<img src="https://images-na.ssl-images-amazon.com/images/I/91V8Nhn8CDL._SL1500_.jpg" class="card-img-top" />
<div class="card-body card-body-topic card-body-topic-align">
<p class="card-sub card-sub-topic-title">Title Here<span class="line-two">Second Line of Text</span></p>
</div>
</a>
</div>
<div class="card card-topic">
<a href="#" class="topic-card-box">
<img src="https://images-na.ssl-images-amazon.com/images/I/91V8Nhn8CDL._SL1500_.jpg" class="card-img-top" />
<div class="card-body card-body-topic card-body-topic-align">
<p class="card-sub card-sub-topic-title">Title Here<span class="line-two">Second Line of Text</span></p>
</div>
</a>
</div>
</div>
<!-- END CARD DECK -->
</div>
<!-- END CARD-CONTIANER -->