[fireknight]

Why go to all that trouble.
Just define the table and the background color.

In the 2 lines

$img1 = "<b><font color=#2f74b3>" . $dispname . "</color></b><br><b><font color=white>".$row["added"]."</color></b><br><a href='$siteurl/details.php?id=$row[id]'><img border='0' src='$row[post_img]' alt=\"$altname / $cat\" height='115' width='170' onmouseover=\" return overlib('<center><h1><b>St??µ??t?pa:</b></h1></center><hr><table width=100%><br><tr><td><img src=$simg1 width=250 border=0></td><td><img src=$simg2 width=250 border=0></td><td><img src=$simg3 width=250 border=0></td><td><img src=$simg4 width=250 border=0></td></tr></table>', CENTER, HEIGHT, 195, WIDTH, 300, FGCOLOR, '#313131', BGCOLOR, '#313131');\" onmouseout=\"return nd();\"></a><br><font color=\"green\"><b>???f?d?te? $seed </font></b><br> <font color=\"red\"><b>?p?d??te? $leech </font></b><br><b><font color=#2f74b3>S????a: <a href=\"details.php?id=".$row["id"].$hit."\">" . $row["comments"] . "</a></b><br>";
$img2 = "<b><font color=#2f74b3>" . $dispname . "</color></b><br><b><font color=white>".$row["added"]."</color></b><br><a href='$siteurl/details.php?id=$row[id]'><img border='0' src='$row[post_img]' alt=\"$altname / $cat\" height='115' width='170' onmouseover=\" return overlib('<center><h1><b>St??µ??t?pa:</b></h1></center><hr><table width=100%><br><br><br><br><br><tr><td><center><font color=#2f74b3 size=4><b>Sorry no screens available</b></font></center></td></tr></table>', CENTER, HEIGHT, 195, WIDTH, 300, FGCOLOR, '#313131', BGCOLOR, '#313131');\" onmouseout=\"return nd();\"></a><br><font color=\"green\"><b>???f?d?te? $seed </font></b><br> <font color=\"red\"><b>?p?d??te? $leech </font></b><br><b><font color=#2f74b3>S????a: <a href=\"details.php?id=".$row["id"].$hit."\">" . $row["comments"] . "</a></b><br>";

Lets just break one line down to show you

$img1 = "<b><font color=#2f74b3>" . $dispname . "</color></b><br>
<b><font color=white>".$row["added"]."</color></b><br>
<a href='$siteurl/details.php?id=$row[id]'>
<img border='0' src='$row[post_img]' alt=\"$altname / $cat\" height='115' width='170' onmouseover=\" return overlib('<center><h1><b>St??µ??t?pa:</b></h1></center><hr>
<table width=100%><br>
<tr
><td><img src=$simg1 width=250 border=0></td>
<td><img src=$simg2 width=250 border=0></td>
<td><img src=$simg3 width=250 border=0></td>
<td><img src=$simg4 width=250 border=0></td>
</tr>
</table>', CENTER, HEIGHT, 195, WIDTH, 300, FGCOLOR, '#313131', BGCOLOR, '#313131');\" onmouseout=\"return nd();\"></a><br><font color=\"green\"><b>???f?d?te? $seed </font></b><br> <font color=\"red\"><b>?p?d??te? $leech </font></b><br><b><font color=#2f74b3>S????a: <a href=\"details.php?id=".$row["id"].$hit."\">" . $row["comments"] . "</a></b><br>";

This part

<table width=100%>

Change it to something like

<table class=imgfgcolor width=100%>

Then add the definition for the table in the css files for each theme.
Changing the background color to match the theme.

table.imgfgcolor
{
    background-color : RED; /* Change the table background color */
    border    : 1px solid #000000;
}