Expand and color destination previews

README.md

@@ -26,9 +26,10 @@ right-clicking with an empty hand. Sneak-right-click with an empty hand to take
 the book back and restore the vanilla lectern. Breaking a Book Stand drops both
 the stored book and a vanilla lectern.
 
-Bound Linking Books request a small, server-validated snapshot around their
-destination and render its blocks as a rotating Ponder scene on the left page.
-The snapshot is visual only; the server independently validates every link.
+Bound Linking Books request a server-validated 9-by-7-by-17 snapshot around
+their destination and render its blocks as a rotating Ponder scene on the left
+page, backed by the destination biome's sky color. The snapshot is visual only;
+the server independently validates every link.
 
 ## Requirements