diff --git a/src/components/Editor.tsx b/src/components/Editor.tsx
index 4780d4b1..73b3254c 100644
--- a/src/components/Editor.tsx
+++ b/src/components/Editor.tsx
@@ -197,6 +197,27 @@ function BlockNoteTab({ content, entries, onNavigateWikilink }: { content: strin
     return () => container.removeEventListener('click', handler as EventListener, true)
   }, [editor])
 
+  // Track active block for highlight — called via onSelectionChange on BlockNoteView
+  const handleSelectionChange = useCallback(() => {
+    const container = document.querySelector('.editor__blocknote-container')
+    if (!container) return
+
+    // Clear previous active
+    container.querySelectorAll('[data-is-active]').forEach(el => {
+      el.removeAttribute('data-is-active')
+    })
+
+    // Use BlockNote's API to get the current block
+    const currentBlock = editor.getTextCursorPosition()?.block
+    if (currentBlock) {
+      // Find the DOM element for this block by its id
+      const blockEl = container.querySelector(`[data-id="${currentBlock.id}"].bn-block-outer`)
+      if (blockEl) {
+        blockEl.setAttribute('data-is-active', 'true')
+      }
+    }
+  }, [editor])
+
   // Suggestion menu items for [[ trigger
   const getWikilinkItems = useCallback(async (query: string) => {
     const items = entries.map(entry => ({
@@ -223,6 +244,7 @@ function BlockNoteTab({ content, entries, onNavigateWikilink }: { content: strin
       <BlockNoteView
         editor={editor}
         theme={isDark ? 'dark' : 'light'}
+        onSelectionChange={handleSelectionChange}
       >
         {/* Wikilink suggestion menu triggered by [[ */}
         <SuggestionMenuController
diff --git a/src/components/EditorTheme.css b/src/components/EditorTheme.css
index 979cf936..44a72a87 100644
--- a/src/components/EditorTheme.css
+++ b/src/components/EditorTheme.css
@@ -11,8 +11,43 @@
   max-width: var(--editor-max-width);
   margin: 0 auto;  /* Center the editor body */
   padding: var(--editor-padding-vertical) var(--editor-padding-horizontal);
+  padding-left: calc(var(--editor-padding-horizontal) + 40px); /* Extra space for block numbers */
   color: var(--colors-text);
   caret-color: var(--colors-cursor);
+  counter-reset: block-number;
+}
+
+/* --- Block numbers (CSS counters) --- 
+   Only count and display numbers for top-level blocks (direct children of the root block-group).
+   The root .bn-block-group is the direct child of the tiptap editor div. */
+.editor__blocknote-container .bn-editor > .bn-block-group > .bn-block-outer {
+  counter-increment: block-number;
+  position: relative;
+}
+
+.editor__blocknote-container .bn-editor > .bn-block-group > .bn-block-outer::after {
+  content: counter(block-number);
+  position: absolute;
+  left: -36px;
+  top: 0;
+  width: 28px;
+  text-align: right;
+  font-size: 12px;
+  line-height: var(--editor-line-height);
+  color: var(--text-faint, #999);
+  pointer-events: none;
+  user-select: none;
+}
+
+/* --- Active block highlight --- */
+.editor__blocknote-container .bn-block-outer[data-is-active="true"] > .bn-block > .bn-block-content {
+  background: var(--bg-hover-subtle, rgba(128, 128, 128, 0.06));
+  border-radius: 3px;
+}
+
+/* Dim non-active block numbers, highlight active */
+.editor__blocknote-container .bn-block-outer[data-is-active="true"]::after {
+  color: var(--text-secondary, #666);
 }
 
 /* Override BlockNote's default line-height on block-outer so our theme controls it */