idk

index.html

@@ -252,6 +252,12 @@
         <option value="edit">edit</option>
       </select>
       <select id="paintColor" title="palette colour — indices only, never an RGB value"></select>
+      <label style="display:flex;align-items:center;gap:6px;color:var(--dim)"
+             title="dim the drawing to trace the frame underneath — editing aid only, never exported">
+        opacity
+        <input type="range" id="paintOpacity" min="10" max="100" value="100" style="width:96px">
+        <output id="paintOpacityv" style="color:var(--accent);min-width:34px"></output>
+      </label>
       <button id="btn-celprev">Copy previous</button>
       <button id="btn-celclear">Clear cel</button>
       <span class="legend" id="paintframe" style="margin:0"></span>
@@ -269,6 +275,11 @@
       <b>edit</b> click a shape to select · drag a vertex or the shape itself ·
       <kbd>Shift</kbd>-click an edge inserts a vertex · <kbd>Alt</kbd>-click a vertex
       removes it · <kbd>Del</kbd> deletes the layer<br>
+      <b>opacity</b> dims the drawing over the registered source frame so you can
+      trace it. It is an editing aid only — never rasterised, never exported, and
+      the flat render is untouched. At 100% the view is exactly the normal
+      composite; below it the placeholder oval is dropped, since it covers the
+      face you turned the slider down to see.<br>
       <b>Copy previous</b> takes the last enabled frame that actually has a drawing
       — skipping empty ones, so it behaves the same before and after you thin the
       strip out. Frames carrying a drawing are marked <b style="color:#c084fc">▣</b>.<br>