JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block_2">Содержание блока 2</div>
<div class="block_1">Содержание блока 1</div>

CSS

.block_1, .block_2 {
    width:200px;
    height:100px;
    border:1px solid black;
}

.block_1 {
    float:left;
}

.block_2 {
    float: right;
}

.block_2:hover +.block_1 {
    border: none;
}