CSS Border

Reveal border onmouseover

Pass your mouse over this text to reveal the border

.borderover{
width:320px;
border:2px dotted red;
padding:0px
}

.borderout{
width:320px;
border:0px;
padding:2px
}

<div class="borderout" onmouseover="this.className='borderover'" onmouseout="this.className='borderout'">Content</div>