JSFiddle - React, Tailwind, and code Playground

by Rolf

HTML

<header>
<nav>
  <details>
  <summary>☰ Menü</summary>
    <ul>
      <li><a href="#">Willkommen</a></li>
      <li><a href="#">Über uns</a></li>
      <li><a href="#">Angebote</a></li>
      <li><a href="#">Preisliste</a></li>
      <li class="newGroup"><a href="#">Will gehen</a></li>
    </ul>
  </details>
</nav> 
<p>
Willkommen auf der Testseite
</p>
</header>
<main>
  <h1>Lorem Ipsum</h1>
</main>
<footer></footer>

CSS

header {
  display: flex;  
  align-items: baseline;
  gap: 0.5em;
  padding: 0.5em;
  background-color: #cfc;
  border-bottom: 3px solid #4f4;
}

header p {
  flex: 1 0 10em;
  font-size: 2em; 
  margin: 0;
  text-align: center;
}

header nav {
  position: relative;
}
header summary { display: none; }
/* Schließt den Internet Explorer aus */
@supports (width: max-content) {
  header summary {
    font: 100 1.5rem sans-serif;
    cursor: pointer;
    padding: 0 0.2em 0 0;
    user-select: none;
    display: block;    /* Für first-letter, und unterdrückt den Marker */
  }
  header summary::first-letter {
    font-weight: 900;
    text-shadow: 0 -1px;
    padding: 0 0.2em;
    border-radius: 0.2em;
    background-color: #6c6;
  }
  header nav ul {
    position: absolute;
  }
}

header nav ul {
  list-style: none;
  border: 1px solid black;
  border-radius: 0.5em;
  padding: 0.5em;
  background-color: white;
  width: max-content;
}

header nav li { 
   padding: 0.1em 0.5em;
}
header nav li.newGroup {
  margin-top: 0.3em;
  padding-top: 0.3em;
  border-top: 1px solid black;
}

span.visually-hidden {
  font-size: 0;
}