besser lesbarer, berichtigter Code

[goldfish]

Also hier die aktualisierte und (hoffentlich) auch lesbarere Fassung:

css: #x {padding:0px; width:10px; height:10px; table-layout:fixed}

<table style="border-collapse:collapse; float:left; margin-left:1em">
      <?php
//---------------------- roter Farbbalken -----------------------
        for ($rr = 255; $rr >= 0; $rr = $rr-15) {
          if (strtoupper(str_pad(dechex($rr),2,"0",STR_PAD_LEFT)) === "$r") {
            $contrast = 255-$rr;
            echo("<tr>
                    <td id="x"
                        style="border:2px solid #".str_pad(dechex($contrast),2,"0",STR_PAD_LEFT)."FFFF;
                                width:6px;
                                background-color:#".str_pad(dechex($rr),2,"0",STR_PAD_LEFT)."0000">
                      <a style="font-size:10px"
                         href="admin.php?c=$c&r=$r">
                        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                      </a>
                    </td>
                  </tr>\n");
          } else {
            echo("<tr>
                    <td id="x"
                        style="background-color:#".str_pad(dechex($rr),2,"0",STR_PAD_LEFT)."0000">
                      <a style="font-size:10px"
                         href="admin.php?c=$c&r=".strtoupper(str_pad(dechex($rr),2,"0",STR_PAD_LEFT))."">
                        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                      </a>
                    </td>
                  </tr>\n");
          }
        }
        echo("</table>\n");
//------------------- grüner Farbbalken -----------------------
[...]
//------------------- rote Farbtabelle -----------------------
        echo("<table style="border-collapse:collapse; float:left; margin-left:1em">\n");
        if ("$r" <> "") {
          $rr = "$r";
          for ($gg = 255; $gg >= 0; $gg = $gg-15) {
            echo("<tr>\n");
            for ($bb = 0; $bb < 256; $bb = $bb+15) {
              echo("<td id="x"
                        style="background-color:#".str_pad($rr,2,"0",STR_PAD_LEFT)
                                                   .str_pad(dechex($gg),2,"0",STR_PAD_LEFT)
                                                   .str_pad(dechex($bb),2,"0",STR_PAD_LEFT)."">
                      <a style="font-size:10px"
                         href="admin.php?c=".strtoupper(str_pad($rr,2,"0",STR_PAD_LEFT)
                                                        .str_pad(dechex($gg),2,"0",STR_PAD_LEFT)
                                                        .str_pad(dechex($bb),2,"0",STR_PAD_LEFT))
                                             ."&r=$r&g=$g&b=$b">
                        &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                      </a>
                    </td>\n");
            }
            echo("</tr>\n");
          }
//------------------- grüne Farbtabelle -----------------------
[...]
//--------------- ansonsten rote Farbtabelle ------------------
        } else {
          $rr = "00";
          for ($gg = 255; $gg >= 0; $gg = $gg-15) {
            echo("<tr>\n");
            for ($bb = 0; $bb < 256; $bb = $bb+15) {
[...]
      ?>
    </table>