non-compliant with OP's suggestion, in that it uses class "obscure" rather than "black" (This is in keeping with using class_names which describe their purpose rather than their action as advocated by some 'separate content from rendering' gurus (tho I'm not sure I buy it. cf, for example, the oft-repeated perl advice to "use meanful $var names." Yeah, "purpose" could eq "meaningful" but in some instances could lead to the likes of use vars qw( $kill1 $kill2 $kill3... instead of ($kill_print $kill_sys $kill_whatever... so WTH!)
<p style="color: black; background-color: black;">A B C D E</p>
The monastery did not like the attempted-css-demo above when it was in actual paragraph tags, but saving the html below (<!DOCTYPE... etc, omitted) will allow you to view its operation.
typo above cq'ed: s/)with/) will/
<html>
<head>
<style type="text/css">
<!--
.obscure {
color: black;
background-color: #000000;
}
-->
</style>
</head>
<body>
<p class="obscure">abcde</p>
<p>View the chars the blackbox above, by highlighting. Done without
+tables.
</p>
</body>
</html>