css/css-sizing/aspect-ratio/fieldset-element-001-ref.html

<!DOCTYPE html>
<title>CSS aspect-ratio Reference: fieldset</title>
<style>
  fieldset {
    width: 200px;
    background: yellow;
  }

  legend {
    background: black;
    color: white;
    padding: 3px 6px;
  }
</style>

<form>
  <fieldset>
    <legend>Choose one item:</legend>

    <input type="radio" id="item1" name="item">
    <label for="item1">item 1</label><br/>

    <input type="radio" id="item2" name="item">
    <label for="item2">item 2</label><br/>

    <input type="radio" id="item3" name="item">
    <label for="item3">item 3</label>
  </fieldset>
</form>