diff --git a/index.html b/index.html
index b4b89ad..9c21ce1 100644
--- a/index.html
+++ b/index.html
@@ -233,6 +233,10 @@
                                 @click="$store.preview.fitMode = 'width'; setPreviewFitMode('width')"
                                 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" :class="{ 'active': $store.preview.fitMode === 'height' }"
+                                @click="$store.preview.fitMode = 'height'; setPreviewFitMode('height')"
+                                id="preview-fit-height"
+                                title="Scale to fit preview pane height (⚠️ for faceted specs, applies to each facet)">Height</button>
                             <button class="btn btn-toggle" :class="{ 'active': $store.preview.fitMode === 'full' }"
                                 @click="$store.preview.fitMode = 'full'; setPreviewFitMode('full')"
                                 id="preview-fit-full"
@@ -308,12 +312,13 @@
                                 </div>
 
                                 <div class="dataset-detail-header">Name</div>
-                                <input type="text" id="dataset-detail-name" class="input"
-                                    placeholder="Dataset name..." :value="dataset?.name" @input="handleNameChange" />
+                                <input type="text" id="dataset-detail-name" class="input" placeholder="Dataset name..."
+                                    :value="dataset?.name" @input="handleNameChange" />
 
                                 <div class="dataset-detail-header">Comment</div>
                                 <textarea id="dataset-detail-comment" class="input textarea"
-                                    placeholder="Add a comment..." rows="3" :value="dataset?.comment" @input="handleCommentChange"></textarea>
+                                    placeholder="Add a comment..." rows="3" :value="dataset?.comment"
+                                    @input="handleCommentChange"></textarea>
 
                                 <div class="dataset-detail-header-row">
                                     <span class="dataset-detail-header">Overview</span>
@@ -344,7 +349,8 @@
                                         <div class="columns-list">
                                             <template x-for="col in dataset?.columnTypes" :key="col.name">
                                                 <div class="column-item">
-                                                    <span class="column-type-icon" x-html="getTypeIcon(col.type)"></span>
+                                                    <span class="column-type-icon"
+                                                        x-html="getTypeIcon(col.type)"></span>
                                                     <span class="column-name" x-text="col.name"></span>
                                                     <span class="column-type" x-text="col.type"></span>
                                                 </div>
@@ -361,7 +367,8 @@
                                             </div>
                                             <div class="stat-item">
                                                 <span class="stat-label">Modified:</span>
-                                                <span id="dataset-detail-modified" x-text="formatDate(dataset?.modified)">-</span>
+                                                <span id="dataset-detail-modified"
+                                                    x-text="formatDate(dataset?.modified)">-</span>
                                             </div>
                                         </div>
                                     </div>
@@ -372,8 +379,7 @@
                                     <div class="preview-toggle-group" x-show="showPreviewToggle">
                                         <button class="btn btn-toggle small"
                                             :class="{ 'active': $store.datasets.previewMode === 'raw' }"
-                                            @click="setPreviewMode('raw')"
-                                            title="Show raw data preview">Raw</button>
+                                            @click="setPreviewMode('raw')" title="Show raw data preview">Raw</button>
                                         <button class="btn btn-toggle small"
                                             :class="{ 'active': $store.datasets.previewMode === 'table' }"
                                             @click="setPreviewMode('table')"
@@ -394,7 +400,7 @@
                                                 <span class="stat-label">📄</span>
                                                 <span>
                                                     <a href="#" @click.prevent="openLinkedSnippet(snippet.id)"
-                                                       class="snippet-link" x-text="snippet.name"></a>
+                                                        class="snippet-link" x-text="snippet.name"></a>
                                                 </span>
                                             </div>
                                         </template>
diff --git a/src/js/config.js b/src/js/config.js
index ac1129e..465dbce 100644
--- a/src/js/config.js
+++ b/src/js/config.js
@@ -190,7 +190,7 @@ document.addEventListener('alpine:init', () => {
 
     // Preview panel fit mode store
     Alpine.store('preview', {
-        fitMode: 'default' // 'default' | 'width' | 'full'
+        fitMode: 'default' // 'default' | 'width' | 'height' | 'full'
     });
 });
 
diff --git a/src/js/editor.js b/src/js/editor.js
index 2d0331d..01d8500 100644
--- a/src/js/editor.js
+++ b/src/js/editor.js
@@ -1,56 +1,53 @@
 // Track preview fit mode
-let previewFitMode = 'default'; // 'default', 'width', or 'full'
+let previewFitMode = 'default'; // 'default', 'width', 'height', or 'full'
 
-// Apply fit mode to spec dimensions
+// Apply fit mode to spec dimensions using Vega-Lite's "container" keyword
 function applyPreviewFitMode(spec, fitMode) {
     if (!spec || typeof spec !== 'object') return spec;
 
     // Clone to avoid mutation
     const modifiedSpec = JSON.parse(JSON.stringify(spec));
 
-    if (fitMode === 'width' || fitMode === 'full') {
-        const previewPane = document.getElementById('vega-preview');
-        if (previewPane) {
-            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;
 
-            // Apply dimensions recursively to handle nested specs
-            function applyDimensions(s) {
-                if (!s || typeof s !== 'object') return;
+        // Apply dimensions based on fit mode
+        if (fitMode === 'width') {
+            s.width = 'container';
+            delete s.height; // Remove height to preserve aspect ratio
+        } else if (fitMode === 'height') {
+            s.height = 'container';
+            delete s.width; // Remove width to preserve aspect ratio
+        } else if (fitMode === 'full') {
+            s.width = 'container';
+            s.height = 'container';
+        }
+        // 'default' mode leaves original dimensions untouched
 
-                // 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);
+        // 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);
         }
     }
-    // 'default' mode leaves original dimensions untouched
+
+    if (fitMode !== 'default') {
+        applyDimensions(modifiedSpec);
+    }
 
     return modifiedSpec;
 }