JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
    <div class="left"></div>
    <div class="middle"></div>
    <div class="right"></div>
</div>

CSS

.wrapper {
    width: 400px;
    height: 100px;
}
.left {
    display: inline;
    float: left;
    background-color: #ccc;
    width: 100px;
    height: 100px;
}
.right {
    display: inline;
    float: right;
    background-color: #610A0A;
    width: 200px;
    height: 100px;
}
.middle {
    float:left;
    display: inline;
    line-height: 0%;
    width: 0px;
    border-top: 100px solid #ccc;
    border-right: 100px solid #610A0A;
}