<div class="legend_container">
<legend>Заголовок</legend>
<input type="text" class="output" value="100" id="farea" oninput="area.value = farea.value"><span>кв.м.</span>
</div>
<input data-price="3000" type="range" name="area" id="area" min="30" max="400" step="5" value="100" oninput="farea.value = area.value">