JSFiddle - React, Tailwind, and code Playground

HTML

<header id="header__">
		<!-- Logo -->
		<div class="header__logo">
			<img src="Assets/Design/Images/logo.png">
		</div>
		<i class="header__respons fa fa-bars" style="padding: 18px 18px;font-size: 31px;"></i>
		<div class="header__nav-left">
			<ul>
				<li><a href="#">Accueil</a></li>
				<li><a href="#">Cours</a></li>
				<li><a href="#">Formations</a></li>
				<li><a href="#">Blog</a></li>
				<li><a href="#">Forum</a></li>
				<li><a href="#">Contact</a></li>
			</ul>
		</div>
		<div class="header__nav-right">
          	<form method="get" action="/search">
            	<span>
            		<i class="fa fa-search"></i>
            		<input id="q" name="q" placeholder="Rechercher...">
            	</span>
          	</form>
          	<a class="btn-register" href="/register">S'inscrire</a>
          	<a class="btn-login" href="/login">Se connecter</a>
        </div>
	</header>

CSS

header#header__ {
	position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 66px;
    width: 100%;
    z-index: 1000;
    color: #6d7a8b;
    font-size: 14px;
    background: whitesmoke;
    border-bottom: 1px solid #e95325;
    transition-duration: .3s;
    box-shadow: 0 2px 10px rgba(109,122,139,.1);
    backface-visibility: hidden;
}
div.header__logo {
	float: left;
    display: block;
    padding-top: 15px;
    height: 51px;
    width: 90px;
    background-color: #e95325;
    text-align: center;
    transition-duration: .3s;
}
div.header__logo > img {
	width: 50px;
    height: 40px;
    color: white;
}
#header__i > .header__respons {
	display: none;
}
div.header__nav-left {
	float: left;
	padding-top: 2px;
	height: 66px;
}
div.header__nav-left ul {
	list-style: none;
}
div.header__nav-left ul > li {
	vertical-align: top;
    padding: 8px 15px;
    display: block;
    float: left;
    font-weight: 700;
    transition-duration: .3s;
}
div.header__nav-left ul li > a {
	text-decoration: none;
	color: #6d7a8b;
	transition-duration: .3s;
	cursor: default;
}
div.header__nav-left ul li > a:hover {
	color: #e95325;
	cursor: default;
}
div.header__nav-right {
	float: right;
}
div.header__nav-right > form {
	display: block;
    position: relative;
    float: left;
    margin-top: 16px;
    margin-right: 70px;
    width: 250px;
    height: 49px;
    font-size: 22px;
    line-height: 34px;
    vertical-align: middle;
    border-radius: 5px;
}
div.header__nav-right form span > a {
	position: absolute;
    top: 0;
    left: 0;
    width: 32px;
    height: 32px;
    text-align: center;
    line-height: 30px;
    font-weight: 400;
    transition-property: font-size;
    transition-duration: .3s;
}
div.header__nav-right form span > i {
	font-size: 18px;
    position: absolute;
    left: 10px;
    top: 9px;
}
div.header__nav-right form span > input {
	display: block;
    float: left;
    position: relative;
    top: 0;
    left: 0;
    background: transparent;
   ...