<div class="panel-toolbar">
  <button id="collapse-panel-btn">
    <svg stroke="#0072ce" fill="none" stroke-width="2" viewBox="0 0 24 24" stroke-linecap="round" stroke-linejoin="round" height="30px" width="30px" xmlns="http://www.w3.org/2000/svg">
      <rect width="18" height="18" x="3" y="3" rx="2" ry="2"></rect>
      <path d="M9 3v18"></path>
      <path d="m16 15-3-3 3-3"></path>
    </svg>
  </button>
</div>