JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <header>
		<div class="header__inner">
			<nav>
				
			</nav>

			<nav class="authorization">
				<input type="submit" class="btn" value="Sign in"/>
			</nav>
		</div>
	</header>
</body>
</html>

CSS

* {
    box-sizing: border-box;
}

body {
    margin: 0;
}

a {
    text-decoration: none;
}

header {
    background-color: #1B2B30;
}

.header__inner {
    display: flex;
    justify-content: space-between;
    padding: 25px 20px;
    font-size: 20px;
    font-family: "Arial";
}

.btn {
    background-color: transparent; 
    border-radius: 5px;
    font-size: 17px;
    padding: 7px 12px;
    border: 2px solid #7915AB;
    color: #FFFFFF;
    cursor: pointer;
}