JSFiddle - React, Tailwind, and code Playground

HTML

<div class='searchBox'>
    <input type='text' placeholder='search...'/>
    <button>Search</button>
</div>

CSS

.searchBox {
    position: relative;
    padding: 10px;
}
input {
    box-sizing: border-box;
    width: 100%;
    border: 1px solid #999;
    background: #fff;
    padding: 10px;
}
button {
    height: 40px;
    background-color: #555;
    padding: 0 10px;
    border: none;
    color: #fff;
    position: absolute;
    top: 10px;
    right: 9px;
}
button:before {
    content: '';
    position: absolute;
    display: block;
    height: 40px;
    top: 0px;
    left: -10px;
    width: 10px;
    background: #fff;
    border-left: 1px solid #999;
}