<div class="input--container input--error">
    <label for="phonenumber" class="input--label">Phone Number </label>
    <input type="number" id="phonenumber" class="input" />
</div>
<div class="input--container input--error">
    <label for="phonenumber" class="input--label">Phone Number </label>
    <input type="number" id="phonenumber" class="input" />
    <span class="input--error--message">Phone number should only contain numbers</span>
</div>