Just add the class .form to your form and take a break.
<form class="form">
<fieldset>
<legend>Numbers fields</legend>
<ol>
<li>
<label for="tel-field">Telephone Field</label>
<input type="tel" id="tel-field" />
</li>
<li>
<label for="text-field22">Number Field</label>
<span>$</span>
<input type="number" id="text-field22" placeholder="0" min="0.15" />
<span>/ month</span>
</li>
<li>
<label for="text-field23">Number Field</label>
<span>$</span>
<input type="number" id="text-field23" placeholder="0" min="0.15" max="100" />
<span>/ click</span>
<span class="explain">min="0.15" max="100"</span>
</li>
<li>
<label for="date-field">Date Field</label>
<input type="date" id="date-field" />
</li>
<li>
<label for="datetime-local">datetime-local</label>
<input type="datetime-local" id="datetime-local" />
</li>
<li>
<label for="month">month</label>
<input type="month" id="month" />
</li>
</ol>
</fieldset>
</form>