<button popovertarget="my-tooltip">
  <p>?</p>
</button>

<div id="my-tooltip" class="tooltip" popover>
  <p>I am a tooltip with more information. I am a tooltip with more information. I am a tooltip with more information. I am a tooltip with more information.<p>
</div>

button {
  anchor-name: --question-mark;
}

#my-tooltip {
  position-anchor: --question-mark;
  inset-area: top;
  position-try-options: flip-block;
}

/* etc. */

button {
  background: #ddd;
  font-size: 1rem;
  font-weight: 800;
  font-family: monospace;
  border-radius: 100%;
  aspect-ratio: 1/1;
  width: 1.5rem;
  line-height: 0;
  border: 2px solid black;
  margin-top: 40dvh;
}

.tooltip {
  font-family: system-ui, sans-serif;
  background: #333;
  color: white;
  font-weight: 400;
  padding: 1rem;
  max-width: 200px;
  line-height: 1.5;
}

body {
  display: grid;
  grid-template-rows: 1fr;
  justify-content: center;
  height: 100vh;
}