Este snippet está sacado directamente de:
http://dropbucket.org/node/420
Algunos recursos para el gif animado:
http://stackoverflow.com/questions/12041051/waiting-loading-transparent-...
.custom-block-class .ajax-progress .message,
.custom-block-class .ajax-progress-throbber .message{
color: white;
font-size: 20px;
padding: 30px;
}
.custom-block-class .ajax-progress .throbber,
.custom-block-class .ajax-progress-throbber .throbber {
float: none;
margin: 250px auto 0 auto;
width: 128px;
height: 128px;
background: url("../images/throbber-image.gif") no-repeat center center;
}
.custom-block-class .ajax-progress,
.custom-block-class .ajax-progress-throbber {
width: 100%;
height: 100%;
background-color: rgba(0, 0, 0, 0.5);
position: fixed;
top: 0;
left: 0;
z-index: 500;
vertical-align: middle;
text-align: center;
}
