<div id="content" class="">
<form id="fuLoginForm" class="InputfieldForm ng-pristine ng-valid" name="fuLoginForm" method="post" action="./" data-colspacing="1">
    <ul class="Inputfields">
        <li class="Inputfield InputfieldText Inputfield_username ui-widget InputfieldStateRequired" id="wrap_username">
           <div class="InputfieldContent ui-widget-content">
             <input id="username" class="required InputfieldMaxWidth" name="username" type="text" maxlength="2048" placeholder="Username">
            </div>
        </li>
    </ul>
</form>

#right-sidebar ul > li::before, #content ul > li::before{
content: "▪ ";
padding-right: 10px;
color: #B41F2A;
}

li[id="wrap_username"] {
  background-color: blue;
}

#fuLoginForm > ul > li::before{
  content: none
}