JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.2/themes/ui-lightness/jquery-ui.css">
<script src="http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.js"></script>

<label for="login">
    User name:<br />
    <div class="label-info">minimum 6 chararcters: letters, numbers and symbols - _ . @</div>
    <input type="text" name="login" class="input-field" value="some value">
</label>

CSS

.label-info {
    display: none;
}

JavaScript

$(".input-field").focus(function() { 
    $(this).addClass("input-field-focus");
    $(this).siblings(".label-info").show();
    return false; 
});
$(".input-field").blur(function() { 
    $(this).removeClass("input-field-focus");
    $(this).siblings(".label-info").hide();
    return false; 
});