From http://pad.wikia.com/wiki/MediaWiki:Wikia.css
table.wikitable {
background: rgba(219,215,188,.5);
}
Although "background: transparent;" may be better in some circumstances.
For that cross-faded 7016458 field:
.a-light-fire{
background: -moz-linear-gradient(left, rgba(253,113,70,0.2) 0%, rgba(250,244,97,0.2) 99%);
background: -webkit-gradient(linear, left top, right bottom, color-stop(0%,rgba(253,113,70,0.2)), color-stop(99%,rgba(250,244,97,0.2)));
background: -webkit-linear-gradient(left, rgba(253,113,70,0.2) 0%,rgba(250,244,97,0.2) 99%);
background: -o-linear-gradient(left, rgba(253,113,70,0.2) 0%,rgba(250,244,97,0.2) 99%);
background: -ms-linear-gradient(left, rgba(253,113,70,0.2) 0%,rgba(250,244,97,0.2) 99%);
background: linear-gradient(to right, rgba(253,113,70,0.2) 0%,rgba(250,244,97,0.2) 99%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#33fd7146', endColorstr='#33faf461',GradientType=1 );}