The Right Way to Declare RGBa Colors

css

/* NON RGBa BROWSERS
  ------------------------------------------------------ */
#wrap { background-color: #000; }
#footer,
#header { background-color: #ccc; }
.section { color: #fff; }

/* HEADER
  ------------------------------------------------------ */
#header { background-color: rgba(204,204,204,.8); }
#header ul { float: right; }
#header li {
  float: left;
  margin-left: 1em;
}
#header li:first-child { margin-left: 0; }

/* WRAP
  ------------------------------------------------------ */
#wrap {
  width: 960px;
  margin: 0 auto;
  background-color: (0,0,0,.7);
}
.section {
  padding: 1em;
  color: rgba(255,255,255,.9);
}

css1

/* NON RGBa BROWSERS
  ------------------------------------------------------ */
#header { border: 1px solid #000; }

/* HEADER
  ------------------------------------------------------ */
#header { border-color: rgba(0,0,0,.7); }

ie_no_go

/* HEADER
  ------------------------------------------------------ */
#header {
  background-color: #ccc;
  background-color: rgba(204,204,204,.8);
}