JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <header>
        <nav>
            <ul>
                <li><button>Uvod</button></li>
                <li><button>O mne</button></li>
                <li><button>Predstaveni</button></li>
                <li><button>Galerie</button></li>
                <li><button>Videa</button></li>
                <li><button>Kontakt</button></li>
            </ul>
        </nav>
    </header>
</body>

CSS

body {
    padding: 0px 0px;
    margin: 0px 0px;
}
header {
    padding: 0px 0px;
    margin: 0px 0px;
}
nav ul {
    list-style-type: none;
}
nav ul li {
    display: inline-block;
    padding: 0px 0px;
    margin: 0px 0px;
}