<form>
  <fieldset>
    <legend>Choose your favorite monster</legend>

    <input type="radio" id="kraken" name="monster" value="K">
    <label for="kraken">Kraken</label><br>

    <input type="radio" id="sasquatch" name="monster" value="S">
    <label for="sasquatch">Sasquatch</label><br>

    <input type="radio" id="mothman" name="monster" value="M">
    <label for="mothman">Mothman</label>
  </fieldset>
</form>

legend {
    background-color: #000;
    color: #fff;
    padding: 3px 6px;
}

input {
    margin: 0.4rem;
}