<div class="input-group">
    <label>Normal input</label>
    <input class="icon user" type="text" placeholder="First Name">
</div>
<div class="input-group">
    <label>Input with focus</label>
    <input class="icon user focus" type="text" placeholder="First Name">
</div>
<div class="input-group">
    <label>Input with error</label>
    <input class="icon user error" type="text" placeholder="First Name">
</div>
<div class="input-group">
    <label>Input without icon</label>
    <input class="" type="text" placeholder="Without icon">
</div>