diff --git a/src/public/app/layouts/desktop_layout.ts b/src/public/app/layouts/desktop_layout.ts
index 945be3e5e..859f9dc04 100644
--- a/src/public/app/layouts/desktop_layout.ts
+++ b/src/public/app/layouts/desktop_layout.ts
@@ -89,6 +89,7 @@ import ContextualHelpButton from "../widgets/floating_buttons/help_button.js";
 import CloseZenButton from "../widgets/close_zen_button.js";
 import type { AppContext } from "./../components/app_context.js";
 import type { WidgetsByParent } from "../services/bundle.js";
+import SwitchSplitOrientationButton from "../widgets/floating_buttons/switch_layout_button.js";
 
 export default class DesktopLayout {
 
@@ -202,6 +203,7 @@ export default class DesktopLayout {
                                                         .child(new WatchedFileUpdateStatusWidget())
                                                         .child(
                                                             new FloatingButtons()
+                                                                .child(new SwitchSplitOrientationButton())
                                                                 .child(new EditButton())
                                                                 .child(new ShowTocWidgetButton())
                                                                 .child(new ShowHighlightsListWidgetButton())
diff --git a/src/public/app/widgets/floating_buttons/switch_layout_button.ts b/src/public/app/widgets/floating_buttons/switch_layout_button.ts
new file mode 100644
index 000000000..6dc2cfde2
--- /dev/null
+++ b/src/public/app/widgets/floating_buttons/switch_layout_button.ts
@@ -0,0 +1,38 @@
+import options from "../../services/options.js";
+import NoteContextAwareWidget from "../note_context_aware_widget.js";
+
+const TPL = `
+<button type="button"
+    class="switch-layout-button"
+    title="Switch layout">
+    <span class="bx bxs-dock-bottom"></span>
+</button>
+`;
+
+export default class SwitchSplitOrientationButton extends NoteContextAwareWidget {
+    isEnabled() {
+        return super.isEnabled()
+            && ["mermaid"].includes(this.note?.type ?? "")
+            && this.note?.isContentAvailable()
+            && this.noteContext?.viewScope?.viewMode === "default";
+    }
+
+    doRender(): void {
+        super.doRender();
+
+        this.$widget = $(TPL);
+        this.$widget.on("click", () => {
+            const currentOrientation = options.get("splitEditorOrientation");
+            options.save("splitEditorOrientation", toggleOrientation(currentOrientation));
+        });
+        this.contentSized();
+    }
+}
+
+function toggleOrientation(orientation: string) {
+    if (orientation === "horizontal") {
+        return "vertical";
+    } else {
+        return "horizontal";
+    }
+}
diff --git a/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts b/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts
index aad7d89ee..01be1cc26 100644
--- a/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts
+++ b/src/public/app/widgets/type_widgets/abstract_split_type_widget.ts
@@ -4,9 +4,11 @@ import EditableCodeTypeWidget from "./editable_code.js";
 import TypeWidget from "./type_widget.js";
 import Split from "split.js";
 import { DEFAULT_GUTTER_SIZE } from "../../services/resizer.js";
+import options from "../../services/options.js";
+import type SwitchSplitOrientationButton from "../floating_buttons/switch_layout_button.js";
 
 const TPL = `\
-<div class="note-detail-split note-detail-printable split-horizontal">
+<div class="note-detail-split note-detail-printable">
     <div class="note-detail-split-first-col">
         <div class="note-detail-split-editor"></div>
         <div class="note-detail-error-container alert alert-warning hidden-ext"></div>
@@ -37,6 +39,7 @@ const TPL = `\
 
         .note-detail-split .note-detail-split-preview {
             transition: opacity 250ms ease-in-out;
+            height: 100%;
         }
 
         .note-detail-split .note-detail-split-preview.on-error {
@@ -58,13 +61,28 @@ const TPL = `\
             height: 100%;
         }
 
-        .note-detail-split-first-col {
+        .note-detail-split.split-horizontal .note-detail-split-first-col {
             flex-direction: column;
         }
 
         /* Vertical layout */
 
+        .note-detail-split.split-vertical {
+            flex-direction: column;
+        }
 
+        .note-detail-split.split-vertical > div {
+            width: 100%;
+            height: 50%;
+        }
+
+        .note-detail-split.split-vertical > .note-detail-split-first-col {
+            border-top: 1px solid var(--main-border-color);
+        }
+
+        .note-detail-split.split-vertical .note-detail-split-second-col {
+            order: -1;
+        }
     </style>
 </div>
 `;
@@ -76,6 +94,7 @@ const TPL = `\
  *
  * - The two panes are resizeable via a split, on desktop. The split can be optionally customized via {@link buildSplitExtraOptions}.
  * - Can display errors to the user via {@link setError}.
+ * - Horizontal or vertical orientation for the editor/preview split, adjustable via {@link SwitchSplitOrientationButton}.
  */
 export default abstract class AbstractSplitTypeWidget extends TypeWidget {
 
@@ -87,6 +106,7 @@ export default abstract class AbstractSplitTypeWidget extends TypeWidget {
     private $editor!: JQuery<HTMLElement>;
     private $errorContainer!: JQuery<HTMLElement>;
     private editorTypeWidget: EditableCodeTypeWidget;
+    private layoutOrientation!: "horizontal" | "vertical";
 
     constructor() {
         super();
@@ -98,6 +118,10 @@ export default abstract class AbstractSplitTypeWidget extends TypeWidget {
     doRender(): void {
         this.$widget = $(TPL);
 
+        const layoutOrientation = options.get("splitEditorOrientation") ?? "horizontal";
+        this.$widget.addClass(`split-${layoutOrientation}`);
+        this.layoutOrientation = layoutOrientation as ("horizontal" | "vertical");
+
         this.$firstCol = this.$widget.find(".note-detail-split-first-col");
         this.$secondCol = this.$widget.find(".note-detail-split-second-col");
         this.$preview = this.$widget.find(".note-detail-split-preview");
@@ -132,7 +156,7 @@ export default abstract class AbstractSplitTypeWidget extends TypeWidget {
         this.splitInstance?.destroy();
         this.splitInstance = Split([ this.$firstCol[0], this.$secondCol[0] ], {
             sizes: [ 50, 50 ],
-            direction: "horizontal",
+            direction: this.layoutOrientation,
             gutterSize: DEFAULT_GUTTER_SIZE,
             ...this.buildSplitExtraOptions()
         });
@@ -163,4 +187,5 @@ export default abstract class AbstractSplitTypeWidget extends TypeWidget {
     getData() {
         return this.editorTypeWidget.getData();
     }
+
 }
diff --git a/src/routes/api/options.ts b/src/routes/api/options.ts
index 1a52d75fa..d4f480615 100644
--- a/src/routes/api/options.ts
+++ b/src/routes/api/options.ts
@@ -10,7 +10,7 @@ import { listSyntaxHighlightingThemes } from "../../services/code_block_theme.js
 import type { OptionNames } from "../../services/options_interface.js";
 
 // options allowed to be updated directly in the Options dialog
-const ALLOWED_OPTIONS = new Set([
+const ALLOWED_OPTIONS = new Set<OptionNames>([
     "eraseEntitiesAfterTimeInSeconds",
     "eraseEntitiesAfterTimeScale",
     "protectedSessionTimeout",
@@ -78,7 +78,8 @@ const ALLOWED_OPTIONS = new Set([
     "backgroundEffects",
     "allowedHtmlTags",
     "redirectBareDomain",
-    "showLoginInShareTheme"
+    "showLoginInShareTheme",
+    "splitEditorOrientation"
 ]);
 
 function getOptions() {
@@ -163,7 +164,10 @@ function getSupportedLocales() {
 }
 
 function isAllowed(name: string) {
-    return ALLOWED_OPTIONS.has(name) || name.startsWith("keyboardShortcuts") || name.endsWith("Collapsed") || name.startsWith("hideArchivedNotes");
+    return (ALLOWED_OPTIONS as Set<string>).has(name)
+        || name.startsWith("keyboardShortcuts")
+        || name.endsWith("Collapsed")
+        || name.startsWith("hideArchivedNotes");
 }
 
 export default {
diff --git a/src/services/options_init.ts b/src/services/options_init.ts
index a3bb95c76..e08833820 100644
--- a/src/services/options_init.ts
+++ b/src/services/options_init.ts
@@ -132,6 +132,9 @@ const defaultOptions: DefaultOption[] = [
     { name: "promotedAttributesOpenInRibbon", value: "true", isSynced: true },
     { name: "editedNotesOpenInRibbon", value: "true", isSynced: true },
 
+    // Appearance
+    { name: "splitEditorOrientation", value: "horizontal", isSynced: true },
+
     // Internationalization
     { name: "locale", value: "en", isSynced: true },
     { name: "firstDayOfWeek", value: "1", isSynced: true },
diff --git a/src/services/options_interface.ts b/src/services/options_interface.ts
index 51b289d4d..f7241956b 100644
--- a/src/services/options_interface.ts
+++ b/src/services/options_interface.ts
@@ -45,6 +45,7 @@ export interface OptionDefinitions extends KeyboardShortcutsOptions<KeyboardActi
     passwordVerificationSalt: string;
     passwordDerivedKeySalt: string;
     encryptedDataKey: string;
+    hoistedNoteId: string;
 
     lastSyncedPull: number;
     lastSyncedPush: number;
@@ -73,6 +74,9 @@ export interface OptionDefinitions extends KeyboardShortcutsOptions<KeyboardActi
     firstDayOfWeek: number;
     languages: string;
 
+    // Appearance
+    splitEditorOrientation: "horziontal" | "vertical";
+
     initialized: boolean;
     isPasswordSet: boolean;
     overrideThemeFonts: boolean;