<style>
  .grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    grid-gap: 20px;
  }

  .grid-item {
    background-color: black;
    border: 4px solid black;
    border-radius: 5px;
    text-align: center;
  }

  .grid-item button {
    width: 100%;
    height: 100px;
    border: none;
    background-color: black;
    font-size: 18px;
    font-weight: bold;
    color: white;
    cursor: pointer;
  }

  .grid-item button:hover {
    color: black;
    background-color: white;
  }
</style>

  <div class="grid">
  
  <div class="grid-item"><button onclick="window.location.href='/display/XPER/Workshops?src=contextnavpagetreemode'">Workshops</button></div>
  <div class="grid-item"><button onclick="window.location.href='/display/XPER/Seminare?src=contextnavpagetreemode'">Seminare</button></div>
  <div class="grid-item"><button onclick="window.location.href='/display/XPER/3D-Druck+Projekte?src=contextnavpagetreemode'">3D-Druck Projekte</button></div>
</div>