JSFiddle - React, Tailwind, and code Playground

HTML

<header id="header" style="width: 100%;">
			<div id="teste"></div>
      <div id="divWrapper"></div>
			<div class="teste2"></div>
</header>

CSS

#divWrapper {
    height: 100px;
    float: left;
    clear: right;
    /* Standard */
    width: calc(100% - 400px);
    /* Firefox */
    width: -moz-calc(100% - 400px);
    /* WebKit */
    width: -webkit-calc(100% - 400px);
    /* Opera */
    width: -o-calc(100% - 400px);
}

#teste {
     float: left;
     width: 200px;
     height: 100px; 
     background-color: red;
}

.teste2 {
    float: left;
    width: 200px;
    height: 100px;
    background-color: black;
}