CODE EXAMPLE FOR HTML

details with input bootstrap

<div class="input-group input-group-lg">
  <span class="input-group-addon" id="sizing-addon1">@</span>
  <input type="text" class="form-control" placeholder="Username" aria-describedby="sizing-addon1">
</div>

<div class="input-group">
  <span class="input-group-addon" id="sizing-addon2">@</span>
  <input type="text" class="form-control" placeholder="Username" aria-describedby="sizing-addon2">
</div>

<div class="input-group input-group-sm">
  <span class="input-group-addon" id="sizing-addon3">@</span>
  <input type="text" class="form-control" placeholder="Username" aria-describedby="sizing-addon3">
</div>