Transparent Header

this partially works but then the bottom home page object are black and I want them white while I want the tabbed content in the listing pages with transparency/opacity so I can have a background image behind the body of content:

.block .tab-content {background-color: #rgba(255,255,255,0.9)

opacity also works in these areas:

BASIC CHANGES
========================================================================== */
body { background:#fdfdfd; color:}

header { background:#373434; }

#core_padding { background: #fdfdfd url(img/bg1.jpg) top left repeat-x;}