JSFiddle - React, Tailwind, and code Playground

HTML

<div class="item-training_info-block"></div>
<i class="item-training_info">sssss</i>

CSS

.item-training_info {
  background-image: url(./images/more-info_ico.png);
  position: absolute;
  top: 10px;
  right: 10px;
  width: 20px;
  height: 20px;
  opacity: 0.3;
  cursor: pointer;
  z-index: 999;
}
.item-training_info-block {
  width: 100%;
  height: 180px;
  position: absolute;
  top: -180px;
  background: red;
  opacity: 0;
  -webkit-transition: all 0.3s ease;
  -moz-transition: all 0.3s ease;
  -o-transition: all 0.3s ease;
  transition: all 0.3s ease;
}
.item-training_info:hover {
  opacity: 0.8;
}
.item-training_info:hover +.item-training_info-block {
  top: 0px;
  opacity: 1;
}