.page_selector{
  display:flex;
}
.ps_item {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 2rem;
}

.Sectiondiv {
    display: flex;
}
.Sectiondiv label {
    display: block;
    text-align: center;
}

<div class="Sectiondiv">
  <div>
    <input type="radio" id="html" name="fav_language" value="1">
    <label for="html">1</label>
  </div>
  <div>
    <input type="radio" id="css" name="fav_language" value="2">
    <label for="css">2</label>
  </div>
  <div>
    <input type="radio" id="javascript" name="fav_language" value="3">
    <label for="javascript">3</label>
  </div>
</div>

试试这个。