Summary: This will modify your (I think it was a button) into another button. I refer to the resource manager discussion button in the resource manager sidebar. It all looks like it works fine so I thought i'd post and share.
Note: You will need the Resource Manager for this enhancement to work.
Install: Upload the image to your /icons folder and then paste the following into your EXTRA.CSS template.
Code:
.resource_description .sidebar .callToAction {
background-color: transparent;
border: 0px solid #F9BC6D;
background: url("@imagePath/xenforo/icons/resource_chat.png") no-repeat scroll center bottom transparent;
border-radius: none;
box-shadow: none;
height: 73px;
margin: 0;
padding: 3px;
text-align: center;
width: 250px;}
.resource_description .sidebar .callToAction:hover { opacity: 0.5; }
.resource_description .sidebar .callToAction span {
border: 0px solid darkred;
background: none transparent;
color: #dff1be;
padding-top: 10px;
padding-left: 35px; }