JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
    <div id="inner1" class="inner">inner1</div>
    <div id="inner2" class="inner">inner2</div>
</div>

CSS

.inner {
    padding: 5px;
    border-radius: 5px;
    top:0px;
    left: 0px;
    position: absolute;
    width: 90px;
    height: 90px;
    background-color: #fff;
}
#inner1 {
    top: 0px;
    height: 50px;
    z-index: 1;
    border-right-width: 0;
    border-radius: 5px 0px 0px 5px;
}
#inner2 {
    border-radius: 0px 5px 5px 5px;
    top:0px;
    left: 10px;
    width: 200px; 
}
.inner {border: solid 1px red}
#outer:hover .inner {border-color: blue}