JSFiddle - React, Tailwind, and code Playground

by web designer

HTML

<div class="red row4 col1">1</div>
<div class="red row3 col2">2</div>
<div class="red row2 col3">3</div>
<div class="red row1 col4">4</div>

<div class="blue row1 col1">1</div>
<div class="blue row2 col2">2</div>
<div class="blue row3 col3">3</div>
<div class="blue row4 col4">4</div>

CSS

.red,.blue {
    width: 40px;
    height: 40px;
    line-height:40px;
    background: red; 
    float:left;
    margin:10px;
    color:#fff;
    text-align:center;
    cursor:pointer;
}
.blue {
    background: blue; 
    display:none;
}
.red.col1:hover ~ .col1{
    display:block !important;
}
.red.col2:hover ~ .col2{
    display:block !important;
}
.red.col3:hover ~ .col3{
    display:block !important;
}
.red.col4:hover ~ .col4{
    display:block !important;
}