只需在按钮和产品数量周围放置一个带有显示Flex或内联块的div，它就应该显示正确。
这应该看起来像这样：

<div class="flex">
  <div class="quantity">
    <label class="screen-reader-text" for="quantity_649c281069093">Irisches Freiland-Huhn mit Gemüse &amp; Kelp-Alge, Adult Menge</label>
    <span class="ui-spinner ui-corner-all ui-widget ui-widget-content" style="height: 40px;"><input type="number" id="quantity_649c281069093" class="input-text qty text ui-spinner-input" name="quantity" value="1" title="Menge" size="4" min="1" max="" step="1" placeholder="" inputmode="numeric" autocomplete="off" aria-valuemin="1" aria-valuenow="1" role="spinbutton">
    <a class="ui-spinner-button ui-corner-br ui-button ui-widget ui-state-default ui-button-text-only ui-spinner-down ui-spinner-up ui-corner-tr ui-button-icon-only" tabindex="-1" role="button" aria-hidden="true"><span class="ui-button-icon ui-icon ui-icon-triangle-1-n"></span><span class="ui-button-icon-space"> </span>
    <span class="ui-icon"><i class="fas fa-plus"></i></span>
    </a>
    <a class="ui-spinner-button ui-corner-tr ui-button ui-widget ui-state-default ui-button-text-only ui-spinner-down ui-corner-br ui-button-icon-only" tabindex="-1" role="button" aria-hidden="true"><span class="ui-button-icon ui-icon ui-icon-triangle-1-s"></span><span class="ui-button-icon-space"> </span>
    <span class="ui-icon"><i class="fas fa-minus"></i></span>
    </a>
    </span>
  </div>
  <button type="submit" class="single_add_to_cart_button button alt wp-element-button">In den Warenkorb</button>
</div>