Something

<?php
print("<html>\n");

if(!isset($_REQUEST['color']))
{
$_REQUEST['color']="FFFFF";
}

print("<body bgcolor=\"#{$_REQUEST['color']}\">\n");

print("<form ".
"action=\"{$_SERVER['PHP_SELF"]}\" " .
"method=\"post\">\n");

print("<b>HTML Color:</b> " .
"<input type=\"text\" name=\"color\" " .
"value=\"{$_REQUEST['color']}\">\n");


print("</form>\n");
print("</body\n");
print("</html>\n");
?>