diff --git a/index.html b/index.html
index 8bb7d1e..cd03d17 100644
--- a/index.html
+++ b/index.html
@@ -165,8 +165,8 @@
                         <span class="view-label">Fit:</span>
                         <div class="view-toggle-group">
                             <button class="btn btn-toggle active" id="preview-fit-default" title="Display at original spec dimensions">Original</button>
-                            <button class="btn btn-toggle" id="preview-fit-width" title="Scale to fit preview pane width">Width</button>
-                            <button class="btn btn-toggle" id="preview-fit-full" title="Scale to fit entire preview pane">Full</button>
+                            <button class="btn btn-toggle" id="preview-fit-width" title="Scale to fit preview pane width (⚠️ for faceted specs, applies to each facet)">Width</button>
+                            <button class="btn btn-toggle" id="preview-fit-full" title="Scale to fit entire preview pane (⚠️ for faceted specs, applies to each facet)">Full</button>
                         </div>
                     </div>
                 </div>
diff --git a/src/js/app.js b/src/js/app.js
index b40f65a..f2cb0a9 100644
--- a/src/js/app.js
+++ b/src/js/app.js
@@ -116,7 +116,7 @@ document.addEventListener('DOMContentLoaded', function () {
     });
 
     // Toggle panel buttons
-    document.querySelectorAll('.toggle-btn').forEach(button => {
+    document.querySelectorAll('[id^="toggle-"][id$="-panel"]').forEach(button => {
         button.addEventListener('click', function () {
             const panelId = this.id.replace('toggle-', '');
             togglePanel(panelId);
diff --git a/src/js/editor.js b/src/js/editor.js
index 8d0746d..32c0e0a 100644
--- a/src/js/editor.js
+++ b/src/js/editor.js
@@ -8,20 +8,46 @@ function applyPreviewFitMode(spec, fitMode) {
     // Clone to avoid mutation
     const modifiedSpec = JSON.parse(JSON.stringify(spec));
 
-    if (fitMode === 'width') {
-        // Fit to width - get preview pane width
+    if (fitMode === 'width' || fitMode === 'full') {
         const previewPane = document.getElementById('vega-preview');
         if (previewPane) {
-            const containerWidth = previewPane.offsetWidth;
-            modifiedSpec.width = containerWidth - 10; // 10px padding for scroll
-            // Keep original aspect ratio by not setting height
-        }
-    } else if (fitMode === 'full') {
-        // Fit to full pane - get both dimensions
-        const previewPane = document.getElementById('vega-preview');
-        if (previewPane) {
-            modifiedSpec.width = previewPane.offsetWidth - 10; // 10px padding
-            modifiedSpec.height = previewPane.offsetHeight - 10; // 10px padding
+            const containerWidth = previewPane.offsetWidth - 10; // 10px padding for scroll
+            const containerHeight = previewPane.offsetHeight - 10; // 10px padding
+
+            // Apply dimensions recursively to handle nested specs
+            function applyDimensions(s) {
+                if (!s || typeof s !== 'object') return;
+
+                // Set dimensions at current level if this is a unit spec or has width/height
+                if (fitMode === 'width') {
+                    s.width = containerWidth;
+                    delete s.height; // Remove height to preserve aspect ratio
+                } else if (fitMode === 'full') {
+                    s.width = containerWidth;
+                    s.height = containerHeight;
+                }
+
+                // Recursively apply to nested specs
+                // For facet specs
+                if (s.spec) {
+                    applyDimensions(s.spec);
+                }
+                // For layer, concat, hconcat, vconcat
+                if (Array.isArray(s.layer)) {
+                    s.layer.forEach(applyDimensions);
+                }
+                if (Array.isArray(s.concat)) {
+                    s.concat.forEach(applyDimensions);
+                }
+                if (Array.isArray(s.hconcat)) {
+                    s.hconcat.forEach(applyDimensions);
+                }
+                if (Array.isArray(s.vconcat)) {
+                    s.vconcat.forEach(applyDimensions);
+                }
+            }
+
+            applyDimensions(modifiedSpec);
         }
     }
     // 'default' mode leaves original dimensions untouched
diff --git a/src/js/snippet-manager.js b/src/js/snippet-manager.js
index a408e3e..650cdab 100644
--- a/src/js/snippet-manager.js
+++ b/src/js/snippet-manager.js
@@ -815,6 +815,7 @@ function duplicateSnippet(snippetId) {
     const newSnippet = createSnippet(duplicateSpec, duplicateName);
     newSnippet.comment = originalSnippet.comment;
     newSnippet.tags = [...originalSnippet.tags];
+    newSnippet.datasetRefs = extractDatasetRefs(duplicateSpec);
 
     SnippetStorage.saveSnippet(newSnippet);