JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header">
    <div class="logo"> 
        <a href="index.php"><img src="#"></a>
    </div>
    <div class="company-header"> 
        <a title="title" href="index.php"><b>Hello</b></a>
    </div>
    <div class="user-header">
        <label class="user"></label> 
        <a class="" href="#">Logout</a>
    </div>
</div>

CSS

div {
    border: 1px solid black; /* added */
}
#header {
    width: 600px;
    background-color: #585D63;
    padding: 15px 0px;
}
#header .logo {
    float: left;
    width: 33%;
    max-width: 180px;
    padding: 5px 30px;
}
#header .logo img {
    max-width: 120px;
    height: auto;
}
#header .company-header {
    font-size: 150%;
    letter-spacing: 1px;
    margin: 0 auto;
    width: 33%;
    text-align: center;
}
#header .user-header {
    float: right;
    width: 33%;
    max-width: 180px;
    padding: 5px 30px;
}
#header .user-header a {
    max-width: 120px;
    height: auto;
}