Pressing Enter after a code fence left the new line outside the block background until the closing ``` was typed. The per-line loop decremented endLine whenever node.to sat at a line start — but @lezer/markdown only puts node.to at a line start for an *unterminated* block (the newline just typed), never for a closed one (whose node ends on the closing-fence line). So the decrement only ever dropped the active editing line. Remove it: the loop now paints every line the node spans, keeping the cursor's line — and the closing ``` — inside the block, while closed blocks still stop at the fence line and never paint the blank line after. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>