You could try copying the black pieces behind the white ones to provide the fill color.

No, that's a kludge I would rather avoid.

How are these?

They appeared to have no bleed-through, but they wouldn't recolor. So, I went ahead with what was working. Taking a variation on your suggestion, I was isolating the part of the path that drew the outline and placing it before the path that drew the image with a color of #f9f9f9. This worked for most pieces. For the Ferz, I couldn't isolate the path due to it relying on m rather than M too much, as it is easier to isolate segments of a path when it is using absolute values. I tried the same thing with the Pawn, but it didn't work. Instead of drawing an outline and carving out sections, it was drawing the right side as a single path then drawing the left side as a single path. So, I couldn't isolate any part of the path for drawing the outline. At this point, every piece is recoloring without bleed-through except for the Pawn.

Ok, I don't know how exactly you need them set up to be recolorable. What I did in the latest ones was insert white sections exactly corresponding to the gaps. That might be as far as I know how to go with this.

For the Pawn, I took your new Pawn and changed the fill color from #ffffff to #f9f9f9 to make it recolorable, and it is now working without bleed-through. Thanks.

Sorry, no, it's not. I need to get the outline shape of the Pawn and put it ahead of the main drawing of the Pawn in the SVG.

Through trial and error I placed a polygon and a circle ahead of the drawing of the Pawn. While it's not a perfect outline of the Pawn, it covers all the interior parts, which is good enough. So, now the Pawn is finally free of bleed-through.

The text by the diagrams looks weird when it reflows so that just one line comes below the images.

Way back on March 8, 2005 I posted a Zillions file for a Shatranj game ending in a blockade stalemate after twenty moves. Four days ago I posted a seventeen move blockade stalemate on the (standard) CHESS page. It now looks like sixteen moves is the shortest possible Shatranj example. H. G. Muller has posted an applet in the Shatranj Comments (May 3, 2021). Clicking "Play it!" and copypasting the game below will show all the moves.

1. a3 a6 2. Nc3 a5 3. Be3 a4 4. Ra2 Ra6 5. Kc1 Rf6 6. Kb1 Rxf2 7. Ka1 Rxg2 8. Nf3 Rxh2 9. Qf2 Rxf2 10. Bh3 Rxf3 11. Rb1 Rxh3 12. Bc1 Nf6 13. d3 Rxd3 14. Ne4 Nxe4 15. c3 Rxc3 16. e3 Rb3 stalemate victory for Black.

Note that it is possible to pre-load an Interactive Diagram with a game, through the parameter moveList. This would save the reader the trouble of copy-pasting the game into the Diagram.

So a Shatranj Diagram with the extra line

moveList=1. a3 a6 2. Nc3 a5 3. Be3 a4 4. Ra2 Ra6 5. Kc1 Rf6 6. Kb1 Rxf2 7. Ka1 Rxg2 8. Nf3 Rxh2 9. Qf2 Rxf2 10. Bh3 Rxf3 11. Rb1 Rxh3 12. Bc1 Nf6 13. d3 Rxd3 14. Ne4 Nxe4 15. c3 Rxc3 16. e3 Rb3

would enable the reader to start navigating through the game immediately, by using the button bar in the AI panel opened by the Play It! link. Like below:

Does this mean I can create an Interactive Diagram for Chess but the King in check cannot travel?

Edit: It does!

Does this mean I can create an Interactive Diagram for Chess but the King in check cannot travel?

Not sure what the 'this' in your message refers to.

Petrifying Check Chess

King in check can't travel. Castling is illegal.

Has this been invented before?

I don't get it. The Diagram is preloaded with a long game, which seems to consist exclusively of illegal moves. When not shown in isolation something goes disastrously wrong (probably because it then uses betzaNew.js from a later Diagram in the Comment listing), and Kings appear everywhere.

What is the purpose of all the holes? Why iiK?

The Diagram as defined would not do what the title suggests: check has no effect on its ability to move at all. It can move from e1/e8 even when in check, and cannot move without capture elsewhere even when in check.

I also don't understand what it has to do with Shatranj...

[Edit] OK, I see: the pre-loaded game tries to capture all the Kings. For some reason this doesn't work with betzaNew.js. You try to make use of the fact that initial moves on royals are forbidden when in check. Inventive, but awful.

[Edit2] Pre-loading games doesn't appear to be Diagram-specific, so it tries to pre-load the wrong game when not viewed in isolation.

[Edit3] The latter is now fixed; it was caused by the fact that the game specified with moveList was loaded with a delay, like it was pasted, but by that time another Diagram on the same page could already be the 'active' one. The script now first sets the active Diagram to the one it uses the move list of.