diff --git a/src/web/App.mjs b/src/web/App.mjs
index e84363f8..6696d5f7 100644
--- a/src/web/App.mjs
+++ b/src/web/App.mjs
@@ -66,6 +66,8 @@ class App {
     setup() {
         document.dispatchEvent(this.manager.appstart);
 
+        // Splitters are created for desktop; ResponsiveLayoutWaiter destroys them
+        // immediately when the container is phone/tablet sized.
         this.initialiseSplitter();
         this.loadLocalStorage();
         this.manager.options.applyPreferredColorScheme();
@@ -309,14 +311,47 @@ class App {
     }
 
 
+    /**
+     * Destroys Split.js instances and removes leftover gutters.
+     * Used when switching to mobile/tablet layouts.
+     */
+    destroySplitters() {
+        if (this.columnSplitter) {
+            this.columnSplitter.destroy();
+            this.columnSplitter = null;
+        }
+        if (this.ioSplitter) {
+            this.ioSplitter.destroy();
+            this.ioSplitter = null;
+        }
+
+        document.querySelectorAll("#workspace-wrapper > .gutter, #IO > .gutter").forEach(g => g.remove());
+
+        // Clear inline sizes Split.js may have left behind
+        ["operations", "recipe", "IO", "input", "output"].forEach(id => {
+            const el = document.getElementById(id);
+            if (el) {
+                el.style.width = "";
+                el.style.height = "";
+                el.style.flex = "";
+            }
+        });
+    }
+
+
     /**
      * Sets up the adjustable splitter to allow the user to resize areas of the page.
      *
      * @param {boolean} [minimise=false] - Set this flag if attempting to minimise frames to 0 width
      */
     initialiseSplitter(minimise=false) {
-        if (this.columnSplitter) this.columnSplitter.destroy();
-        if (this.ioSplitter) this.ioSplitter.destroy();
+        this.destroySplitters();
+
+        // Do not create splitters while in a touch layout — CSS owns the layout.
+        if (this.manager.responsive && this.manager.responsive.isTouchLayout()) {
+            this.adjustComponentSizes();
+            return;
+        }
 
         this.columnSplitter = Split(["#operations", "#recipe", "#IO"], {
             sizes: [20, 30, 50],
@@ -629,6 +664,10 @@ class App {
      * Resets the splitter positions to default.
      */
     resetLayout() {
+        if (!this.columnSplitter || !this.ioSplitter) {
+            this.adjustComponentSizes();
+            return;
+        }
         this.columnSplitter.setSizes([20, 30, 50]);
         this.ioSplitter.setSizes([50, 50]);
         this.adjustComponentSizes();
diff --git a/src/web/HTMLOperation.mjs b/src/web/HTMLOperation.mjs
index 0ba0ffc8..e703c343 100755
--- a/src/web/HTMLOperation.mjs
+++ b/src/web/HTMLOperation.mjs
@@ -90,6 +90,8 @@ class HTMLOperation {
 
         html += `</div>
         <div class="recip-icons">
+            <i class="material-icons op-reorder-up responsive-only" title="Move up" aria-label="Move operation up">arrow_upward</i>
+            <i class="material-icons op-reorder-down responsive-only" title="Move down" aria-label="Move operation down">arrow_downward</i>
             <i class="material-icons breakpoint" title="Set breakpoint" break="false" data-help-title="Setting breakpoints" data-help="Setting a breakpoint on an operation will cause execution of the Recipe to pause when it reaches that operation.">pause</i>
             <i class="material-icons disable-icon" title="Disable operation" disabled="false" data-help-title="Disabling operations" data-help="Disabling an operation will prevent it from being executed when the Recipe is baked. Execution will skip over the disabled operation and continue with subsequent operations.">not_interested</i>
             <i class="material-icons hide-args-icon" title="Hide operation's arguments" hide-args="false" data-help-title="Hide operation's arguments" data-help="Hiding an operation's argument will save space in the Recipe window. Execution will still take place with the selected argument options.">keyboard_arrow_up</i>
diff --git a/src/web/Manager.mjs b/src/web/Manager.mjs
index 7cde638d..5ed28df6 100755
--- a/src/web/Manager.mjs
+++ b/src/web/Manager.mjs
@@ -18,6 +18,7 @@ import BindingsWaiter from "./waiters/BindingsWaiter.mjs";
 import BackgroundWorkerWaiter from "./waiters/BackgroundWorkerWaiter.mjs";
 import TabWaiter from "./waiters/TabWaiter.mjs";
 import TimingWaiter from "./waiters/TimingWaiter.mjs";
+import ResponsiveLayoutWaiter from "./waiters/ResponsiveLayoutWaiter.mjs";
 
 
 /**
@@ -74,6 +75,7 @@ class Manager {
         this.seasonal    = new SeasonalWaiter(this.app, this);
         this.bindings    = new BindingsWaiter(this.app, this);
         this.background  = new BackgroundWorkerWaiter(this.app, this);
+        this.responsive  = new ResponsiveLayoutWaiter(this.app, this);
 
         // Object to store dynamic handlers to fire on elements that may not exist yet
         this.dynamicHandlers = {};
@@ -95,6 +97,7 @@ class Manager {
         this.bindings.updateKeybList();
         this.background.registerChefWorker();
         this.seasonal.load();
+        this.responsive.setup();
 
         this.confirmWaitersLoaded();
     }
@@ -148,6 +151,7 @@ class Manager {
         // Operations
         this.addMultiEventListener("#search", "keyup paste search", this.ops.searchOperations, this.ops);
         this.addDynamicListener(".op-list li.operation", "dblclick", this.ops.operationDblclick, this.ops);
+        this.addDynamicListener(".op-list li.operation", "click", this.ops.operationClick, this.ops);
         document.getElementById("edit-favourites").addEventListener("click", this.ops.editFavouritesClick.bind(this.ops));
         document.getElementById("save-favourites").addEventListener("click", this.ops.saveFavouritesClick.bind(this.ops));
         document.getElementById("reset-favourites").addEventListener("click", this.ops.resetFavouritesClick.bind(this.ops));
@@ -160,6 +164,8 @@ class Manager {
         this.addDynamicListener(".hide-args-icon", "click", this.recipe.hideArgsClick, this.recipe);
         this.addDynamicListener(".disable-icon", "click", this.recipe.disableClick, this.recipe);
         this.addDynamicListener(".breakpoint", "click", this.recipe.breakpointClick, this.recipe);
+        this.addDynamicListener(".op-reorder-up", "click", this.recipe.moveOpUp, this.recipe);
+        this.addDynamicListener(".op-reorder-down", "click", this.recipe.moveOpDown, this.recipe);
         this.addDynamicListener("#rec-list li.operation", "dblclick", this.recipe.operationDblclick, this.recipe);
         this.addDynamicListener("#rec-list li.operation > div", "dblclick", this.recipe.operationChildDblclick, this.recipe);
         this.addDynamicListener("#rec-list .dropdown-menu.toggle-dropdown a", "click", this.recipe.dropdownToggleClick, this.recipe);
diff --git a/src/web/html/index.html b/src/web/html/index.html
index 6ce8dd9a..0f53da2d 100755
--- a/src/web/html/index.html
+++ b/src/web/html/index.html
@@ -24,6 +24,7 @@
     <head>
         <meta charset="UTF-8">
         <title>CyberChef</title>
+        <meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover">
 
         <meta name="copyright" content="Crown Copyright 2016-<%= htmlWebpackPlugin.options.compileYear %>" />
         <meta name="description" content="The Cyber Swiss Army Knife - a web app for encryption, encoding, compression and data analysis" />
@@ -145,7 +146,10 @@
         <button type="button" aria-label="Edit Favourites" class="btn btn-warning bmd-btn-icon" id="edit-favourites" data-toggle="tooltip" title="Edit favourites">
             <i class="material-icons" aria-hidden="true">star</i>
         </button>
-        <div tabindex="0" id="content-wrapper">
+        <div tabindex="0" id="content-wrapper" class="cyberchef-root" data-layout="desktop" data-mobile-pane="recipe" data-data-segment="input">
+            <div id="ops-overlay" hidden aria-hidden="true">
+                <div id="ops-scrim"></div>
+            </div>
             <div id="banner" class="row">
                 <div class="col" style="text-align: left; padding-left: 10px;">
                     <a href="#" data-toggle="modal" data-target="#download-modal" data-help-title="Downloading CyberChef" data-help="<p>CyberChef can be downloaded to run locally or hosted within your own network. It has no server-side component so all that is required is that the ZIP file is uncompressed and the files are accessible.</p><p>As a user, it is worth noting that unofficial versions of CyberChef could have been modified to introduce Input and/or Recipe exfiltration. We recommend always using the official, open source, up-to-date version of CyberChef hosted at <a href='https://gchq.github.io/CyberChef'>https://gchq.github.io/CyberChef</a> if accessible.</p><p>The Network tab in your browser's Developer console (F12) can be used to inspect the network requests made by a website. This can confirm that no data is uploaded when a CyberChef recipe is baked.</p>">Download CyberChef <i class="material-icons">file_download</i></a>
@@ -163,12 +167,26 @@
                     </span>
                 </div>
                 <div class="col" style="text-align: right; padding-right: 0;">
+                    <button type="button" id="tablet-ops-toggle" class="btn btn-primary btn-sm tablet-only" aria-label="Open operations" aria-expanded="false" aria-controls="operations">
+                        <i class="material-icons" aria-hidden="true">menu</i> Ops
+                    </button>
                     <a href="#" id="options" data-help-title="Options and Settings" data-help="Configurable options to change how CyberChef behaves. These settings are stored in your browser's local storage, meaning they will persist between sessions that use the same browser profile.">Options <i class="material-icons">settings</i></a>
                     <a href="#" id="support" data-toggle="modal" data-target="#support-modal" data-help-title="About / Support" data-help="This pane provides information about the CyberChef web app, how to use some of the features, and how to raise bug reports.">About / Support <i class="material-icons">help</i></a>
                 </div>
             </div>
             <div id="workspace-wrapper">
-                <div id="operations" class="split split-horizontal no-select">
+                <div id="operations" class="split split-horizontal no-select" role="dialog" aria-label="Operations">
+                    <div id="ops-sheet-header" class="mobile-only responsive-chrome">
+                        <div style="width:100%;">
+                            <div class="ops-handle" aria-hidden="true"></div>
+                            <div style="display:flex;align-items:center;justify-content:space-between;">
+                                <strong>Operations</strong>
+                                <button type="button" id="ops-close" class="btn btn-primary bmd-btn-icon" aria-label="Close operations">
+                                    <i class="material-icons" aria-hidden="true">close</i>
+                                </button>
+                            </div>
+                        </div>
+                    </div>
                     <div class="title no-select" data-help-title="Operations list" data-help="<p>The Operations list contains all the operations in CyberChef arranged into categories. Some operations may be present in multiple categories. You can search for operations using the search box.</p><p>To use an operation, either double click it, or drag it into the Recipe pane. You will then be able to configure its arguments (or 'Ingredients' in CyberChef terminology).</p>">
                         Operations
                         <span class="op-count"></span>
@@ -222,6 +240,10 @@
                 </div>
 
                 <div class="split split-horizontal" id="IO">
+                    <div id="data-segment-bar" class="mobile-only" role="tablist" aria-label="Input and output">
+                        <button type="button" id="seg-input" role="tab" aria-selected="true" class="active">Input</button>
+                        <button type="button" id="seg-output" role="tab" aria-selected="false">Output</button>
+                    </div>
                     <div id="input" class="split no-select" data-help-title="Input pane" data-help="<p>Input data can be entered by typing it in, pasting it in, dragging it in, or using the 'Load file' or 'Load folder' buttons.</p><p>CyberChef does its best to represent data as accurately as possible to ensure you know exactly what you are working with. Non-printable characters are represented using control character pictures, for example a null byte (0x00) is displayed like this: <span title='Control character null' aria-label='Control character null' class='cm-specialChar'>␀</span>.</p>">
                         <div class="title no-select">
                             <label for="input-text">Input</label>
@@ -341,6 +363,19 @@
                     </div>
                 </div>
             </div>
+            <nav id="mobile-nav" class="mobile-only" role="tablist" aria-label="Main navigation">
+                <button type="button" id="nav-recipe" role="tab" aria-selected="true" class="active" data-pane="recipe">
+                    <i class="material-icons" aria-hidden="true">list_alt</i>
+                    Recipe
+                </button>
+                <button type="button" id="nav-ops-fab" aria-label="Add operation" aria-expanded="false" aria-controls="operations">
+                    <i class="material-icons" aria-hidden="true">add</i>
+                </button>
+                <button type="button" id="nav-data" role="tab" aria-selected="false" data-pane="data">
+                    <i class="material-icons" aria-hidden="true">swap_horiz</i>
+                    Data
+                </button>
+            </nav>
         </div>
 
         <div class="modal fade" id="save-modal" tabindex="-1" role="dialog">
diff --git a/src/web/stylesheets/index.css b/src/web/stylesheets/index.css
index 0565399f..6962d7ae 100755
--- a/src/web/stylesheets/index.css
+++ b/src/web/stylesheets/index.css
@@ -34,6 +34,7 @@
 @import "./layout/_operations.css";
 @import "./layout/_recipe.css";
 @import "./layout/_structure.css";
+@import "./layout/_responsive.css";
 
 /* Operations */
 @import "./operations/diff.css";
diff --git a/src/web/stylesheets/layout/_responsive.css b/src/web/stylesheets/layout/_responsive.css
new file mode 100644
index 00000000..176f4766
--- /dev/null
+++ b/src/web/stylesheets/layout/_responsive.css
@@ -0,0 +1,382 @@
+/**
+ * Responsive phone / tablet layout for CyberChef.
+ * Driven by [data-layout] on #content-wrapper (set via ResizeObserver).
+ *
+ * @author blepman
+ * @license Apache-2.0
+ */
+
+/* ---- Chrome defaults (hidden on desktop) ---- */
+
+.responsive-chrome,
+.mobile-only,
+.tablet-only,
+.responsive-only {
+    display: none !important;
+}
+
+#ops-overlay {
+    display: none;
+}
+
+/* ---- Shared non-desktop ---- */
+
+[data-layout="mobile"] .responsive-only,
+[data-layout="tablet"] .responsive-only {
+    display: inline-flex !important;
+}
+
+[data-layout="mobile"] .gutter,
+[data-layout="tablet"] .gutter {
+    display: none !important;
+}
+
+[data-layout="mobile"] #workspace-wrapper,
+[data-layout="tablet"] #workspace-wrapper {
+    display: flex;
+    flex-direction: row;
+    overflow: hidden;
+}
+
+[data-layout="mobile"] #operations.split,
+[data-layout="mobile"] #recipe.split,
+[data-layout="mobile"] #IO.split,
+[data-layout="tablet"] #operations.split,
+[data-layout="tablet"] #recipe.split,
+[data-layout="tablet"] #IO.split {
+    float: none;
+    width: auto;
+    height: auto;
+}
+
+[data-layout="mobile"] #banner .col:first-child,
+[data-layout="tablet"] #banner .col:first-child {
+    display: none;
+}
+
+[data-layout="mobile"] #banner,
+[data-layout="tablet"] #banner {
+    min-height: 40px;
+    align-items: center;
+}
+
+[data-layout="mobile"] #workspace-wrapper,
+[data-layout="tablet"] #workspace-wrapper {
+    top: 40px;
+}
+
+/* Reorder / touch affordances */
+.op-reorder-up,
+.op-reorder-down {
+    cursor: pointer;
+    font-size: 20px !important;
+    margin-left: 2px;
+    min-width: 44px;
+    min-height: 44px;
+    align-items: center;
+    justify-content: center;
+    vertical-align: middle;
+}
+
+.op-list li.operation {
+    position: relative;
+}
+
+/* ---- Tablet (768–1023) ---- */
+
+[data-layout="tablet"] .tablet-only {
+    display: inline-flex !important;
+}
+
+[data-layout="tablet"] #recipe {
+    flex: 1 1 45%;
+    min-width: 0;
+    height: 100%;
+    border-right: 1px solid var(--primary-border-colour);
+}
+
+[data-layout="tablet"] #IO {
+    flex: 1 1 55%;
+    min-width: 0;
+    height: 100%;
+    display: flex;
+    flex-direction: column;
+}
+
+[data-layout="tablet"] #IO #input,
+[data-layout="tablet"] #IO #output {
+    flex: 1 1 50%;
+    width: 100%;
+    height: 50%;
+    min-height: 0;
+}
+
+[data-layout="tablet"] #operations {
+    position: fixed;
+    top: 40px;
+    left: 0;
+    bottom: 0;
+    width: min(360px, 90%);
+    z-index: 1200;
+    background: var(--primary-background-colour);
+    border-right: 1px solid var(--primary-border-colour);
+    transform: translateX(-105%);
+    transition: transform 0.2s ease;
+    box-shadow: 2px 0 12px rgba(0, 0, 0, 0.2);
+}
+
+[data-layout="tablet"].ops-open #operations,
+body[data-layout="tablet"] #content-wrapper.ops-open #operations {
+    transform: translateX(0);
+}
+
+[data-layout="tablet"] #ops-overlay:not([hidden]) {
+    display: block;
+    position: fixed;
+    inset: 40px 0 0 0;
+    z-index: 1100;
+}
+
+[data-layout="tablet"] #ops-scrim {
+    position: absolute;
+    inset: 0;
+    background: rgba(0, 0, 0, 0.45);
+}
+
+[data-layout="tablet"] #tablet-ops-toggle {
+    display: inline-flex !important;
+    align-items: center;
+    gap: 4px;
+    margin-right: 8px;
+    min-height: 44px;
+    padding: 0 12px;
+}
+
+[data-layout="tablet"] #data-segment-bar,
+[data-layout="tablet"] #mobile-nav {
+    display: none !important;
+}
+
+/* ---- Mobile (<768) ---- */
+
+[data-layout="mobile"] .mobile-only {
+    display: flex !important;
+}
+
+[data-layout="mobile"] #workspace-wrapper {
+    flex-direction: column;
+    bottom: 56px;
+}
+
+[data-layout="mobile"] #recipe,
+[data-layout="mobile"] #IO {
+    flex: 1 1 auto;
+    width: 100%;
+    min-height: 0;
+    height: 100%;
+    display: none;
+    flex-direction: column;
+}
+
+[data-layout="mobile"][data-mobile-pane="recipe"] #recipe,
+#content-wrapper[data-layout="mobile"][data-mobile-pane="recipe"] #recipe {
+    display: flex;
+}
+
+[data-layout="mobile"][data-mobile-pane="data"] #IO,
+#content-wrapper[data-layout="mobile"][data-mobile-pane="data"] #IO {
+    display: flex;
+}
+
+[data-layout="mobile"] #IO #input,
+[data-layout="mobile"] #IO #output {
+    flex: 1 1 auto;
+    width: 100%;
+    height: 100%;
+    min-height: 0;
+    display: none;
+    flex-direction: column;
+}
+
+[data-layout="mobile"][data-data-segment="input"] #IO #input,
+#content-wrapper[data-layout="mobile"][data-data-segment="input"] #IO #input {
+    display: flex;
+}
+
+[data-layout="mobile"][data-data-segment="output"] #IO #output,
+#content-wrapper[data-layout="mobile"][data-data-segment="output"] #IO #output {
+    display: flex;
+}
+
+[data-layout="mobile"] #data-segment-bar {
+    display: flex !important;
+    flex: 0 0 auto;
+    gap: 0;
+    border-bottom: 1px solid var(--primary-border-colour);
+    background: var(--secondary-background-colour);
+}
+
+[data-layout="mobile"] #data-segment-bar button {
+    flex: 1;
+    min-height: 44px;
+    border: 0;
+    background: transparent;
+    color: var(--primary-font-colour);
+    font-weight: 600;
+    cursor: pointer;
+}
+
+[data-layout="mobile"] #data-segment-bar button.active {
+    border-bottom: 3px solid var(--primary-font-colour);
+    background: var(--primary-background-colour);
+}
+
+[data-layout="mobile"][data-mobile-pane="recipe"] #data-segment-bar {
+    display: none !important;
+}
+
+/* Sticky Bake bar sits above bottom nav */
+[data-layout="mobile"] #controls,
+[data-layout="mobile"] #controls.mobile-controls-bar {
+    position: fixed;
+    left: 0;
+    right: 0;
+    bottom: 56px;
+    z-index: 900;
+    padding: 8px 4px;
+    width: 100%;
+}
+
+[data-layout="mobile"] #rec-list {
+    padding-bottom: 88px;
+}
+
+[data-layout="mobile"] #IO #input-wrapper,
+[data-layout="mobile"] #IO #output-wrapper {
+    padding-bottom: 88px;
+}
+
+[data-layout="mobile"] #operations {
+    position: fixed;
+    left: 0;
+    right: 0;
+    bottom: 0;
+    top: auto;
+    height: 85dvh;
+    max-height: 85vh;
+    z-index: 1300;
+    background: var(--primary-background-colour);
+    border-radius: 12px 12px 0 0;
+    transform: translateY(105%);
+    transition: transform 0.25s ease;
+    box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.25);
+    width: 100%;
+}
+
+[data-layout="mobile"].ops-open #operations,
+#content-wrapper[data-layout="mobile"].ops-open #operations {
+    transform: translateY(0);
+}
+
+[data-layout="mobile"] #ops-overlay:not([hidden]) {
+    display: block;
+    position: fixed;
+    inset: 0;
+    z-index: 1200;
+}
+
+[data-layout="mobile"] #ops-scrim {
+    position: absolute;
+    inset: 0;
+    background: rgba(0, 0, 0, 0.5);
+}
+
+[data-layout="mobile"] #ops-sheet-header {
+    display: flex !important;
+    align-items: center;
+    justify-content: space-between;
+    padding: 8px 12px;
+    border-bottom: 1px solid var(--primary-border-colour);
+    min-height: 48px;
+}
+
+[data-layout="mobile"] #ops-sheet-header .ops-handle {
+    width: 40px;
+    height: 4px;
+    border-radius: 2px;
+    background: var(--secondary-border-colour);
+    margin: 4px auto 8px;
+}
+
+[data-layout="mobile"] #mobile-nav {
+    display: flex !important;
+    position: fixed;
+    left: 0;
+    right: 0;
+    bottom: 0;
+    height: 56px;
+    z-index: 1000;
+    background: var(--secondary-background-colour);
+    border-top: 1px solid var(--primary-border-colour);
+    align-items: stretch;
+    justify-content: space-around;
+    padding-bottom: env(safe-area-inset-bottom, 0);
+}
+
+[data-layout="mobile"] #mobile-nav button {
+    flex: 1;
+    border: 0;
+    background: transparent;
+    color: var(--primary-font-colour);
+    font-size: 12px;
+    font-weight: 600;
+    cursor: pointer;
+    min-height: 44px;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    gap: 2px;
+}
+
+[data-layout="mobile"] #mobile-nav button.active {
+    color: var(--input-highlight-colour, #4caf50);
+}
+
+[data-layout="mobile"] #mobile-nav .material-icons {
+    font-size: 22px;
+}
+
+[data-layout="mobile"] #nav-ops-fab {
+    flex: 0 0 56px;
+    width: 56px;
+    height: 56px;
+    margin-top: -12px;
+    border-radius: 50%;
+    background: var(--primary-font-colour);
+    color: var(--primary-background-colour);
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.3);
+}
+
+[data-layout="mobile"] #nav-ops-fab .material-icons {
+    font-size: 28px;
+}
+
+[data-layout="mobile"] #tablet-ops-toggle {
+    display: none !important;
+}
+
+@media (prefers-reduced-motion: reduce) {
+    [data-layout="mobile"] #operations,
+    [data-layout="tablet"] #operations {
+        transition: none;
+    }
+}
+
+/* Fallback when container queries are unsupported: mirror via body attribute already set */
+@supports (container-type: inline-size) {
+    #content-wrapper.cyberchef-root {
+        container-type: inline-size;
+        container-name: cyberchef;
+    }
+}
diff --git a/src/web/waiters/OperationsWaiter.mjs b/src/web/waiters/OperationsWaiter.mjs
index 6c2de064..348f6b99 100755
--- a/src/web/waiters/OperationsWaiter.mjs
+++ b/src/web/waiters/OperationsWaiter.mjs
@@ -229,9 +229,46 @@ class OperationsWaiter {
      * @param {event} e
      */
     operationDblclick(e) {
-        const li = e.target;
+        const li = e.target.closest("li.operation");
+        if (!li) return;
 
-        this.manager.recipe.addOperation(li.textContent);
+        this.manager.recipe.addOperation(this.operationNameFromListItem(li));
+    }
+
+
+    /**
+     * Tap-to-add on phone/tablet layouts (single click).
+     * Desktop keeps double-click / drag-and-drop.
+     *
+     * @param {event} e
+     */
+    operationClick(e) {
+        if (!this.manager.responsive || !this.manager.responsive.isTouchLayout()) {
+            return;
+        }
+
+        // Ignore clicks on remove icons (favourites editor)
+        if (e.target.closest(".remove-icon")) return;
+
+        const li = e.target.closest("li.operation");
+        if (!li || !li.closest(".op-list")) return;
+
+        e.preventDefault();
+        this.manager.recipe.addOperation(this.operationNameFromListItem(li));
+        this.manager.responsive.afterOperationAdded();
+    }
+
+
+    /**
+     * Extract operation name from a list item without icon ligature text.
+     *
+     * @param {Element} li
+     * @returns {string}
+     */
+    operationNameFromListItem(li) {
+        const clone = li.cloneNode(true);
+        clone.querySelectorAll("i").forEach(icon => icon.remove());
+        return clone.textContent.trim();
     }
 
 
diff --git a/src/web/waiters/OutputWaiter.mjs b/src/web/waiters/OutputWaiter.mjs
index 2b2cb096..a4db8e6d 100755
--- a/src/web/waiters/OutputWaiter.mjs
+++ b/src/web/waiters/OutputWaiter.mjs
@@ -1531,6 +1531,13 @@ class OutputWaiter {
      * Resizes the output frame to be as large as possible, or restores it to its original size.
      */
     maximiseOutputClick(e) {
+        if (this.manager.responsive && this.manager.responsive.isTouchLayout()) {
+            // On phone/tablet, switch to the Data/Output view instead of Split.js maximise.
+            this.manager.responsive.showMobilePane("data");
+            this.manager.responsive.showDataSegment("output");
+            return;
+        }
+
         const el = e.target.id === "maximise-output" ? e.target : e.target.parentNode;
 
         if (el.getAttribute("data-original-title").indexOf("Maximise") === 0) {
diff --git a/src/web/waiters/RecipeWaiter.mjs b/src/web/waiters/RecipeWaiter.mjs
index e4198cd5..73e67f20 100755
--- a/src/web/waiters/RecipeWaiter.mjs
+++ b/src/web/waiters/RecipeWaiter.mjs
@@ -463,6 +463,36 @@ class RecipeWaiter {
     }
 
 
+    /**
+     * Move a recipe operation one step up (touch layout affordance).
+     *
+     * @param {event} e
+     */
+    moveOpUp(e) {
+        e.preventDefault();
+        e.stopPropagation();
+        const li = e.target.closest("li.operation");
+        if (!li || !li.previousElementSibling) return;
+        li.parentNode.insertBefore(li, li.previousElementSibling);
+        window.dispatchEvent(this.manager.statechange);
+    }
+
+
+    /**
+     * Move a recipe operation one step down (touch layout affordance).
+     *
+     * @param {event} e
+     */
+    moveOpDown(e) {
+        e.preventDefault();
+        e.stopPropagation();
+        const li = e.target.closest("li.operation");
+        if (!li || !li.nextElementSibling) return;
+        li.parentNode.insertBefore(li.nextElementSibling, li);
+        window.dispatchEvent(this.manager.statechange);
+    }
+
+
     /**
      * Handler for operation dropdown events from toggleString arguments.
      * Sets the selected option as the name of the button.
diff --git a/src/web/waiters/ResponsiveLayoutWaiter.mjs b/src/web/waiters/ResponsiveLayoutWaiter.mjs
new file mode 100644
index 00000000..368b6ea0
--- /dev/null
+++ b/src/web/waiters/ResponsiveLayoutWaiter.mjs
@@ -0,0 +1,283 @@
+/**
+ * Responsive phone / tablet layout for CyberChef.
+ * Uses container width (ResizeObserver) so iframe embeds behave correctly.
+ *
+ * @author blepman
+ * @license Apache-2.0
+ */
+
+const BREAKPOINT_MOBILE = 768;
+const BREAKPOINT_TABLET = 1024;
+
+/**
+ * Manages layout modes: mobile | tablet | desktop.
+ */
+class ResponsiveLayoutWaiter {
+
+    /**
+     * @param {App} app
+     * @param {Manager} manager
+     */
+    constructor(app, manager) {
+        this.app = app;
+        this.manager = manager;
+        this.root = null;
+        this.observer = null;
+        this.currentMode = null;
+        this.mobilePane = "recipe"; // recipe | data
+        this.dataSegment = "input"; // input | output
+        this.opsOpen = false;
+    }
+
+
+    /**
+     * Initialise observer and chrome after DOM is ready.
+     */
+    setup() {
+        this.root = document.getElementById("content-wrapper");
+        if (!this.root) return;
+
+        this.root.classList.add("cyberchef-root");
+        this.root.style.containerType = "inline-size";
+        this.root.style.containerName = "cyberchef";
+
+        this.bindChrome();
+
+        if (typeof ResizeObserver !== "undefined") {
+            this.observer = new ResizeObserver(entries => {
+                const width = entries[0].contentRect.width;
+                this.applyMode(this.modeFromWidth(width));
+            });
+            this.observer.observe(this.root);
+            this.applyMode(this.modeFromWidth(this.root.getBoundingClientRect().width));
+        } else {
+            const onResize = () => {
+                this.applyMode(this.modeFromWidth(window.innerWidth));
+            };
+            window.addEventListener("resize", onResize);
+            onResize();
+        }
+    }
+
+
+    /**
+     * @param {number} width
+     * @returns {"mobile"|"tablet"|"desktop"}
+     */
+    modeFromWidth(width) {
+        if (width < BREAKPOINT_MOBILE) return "mobile";
+        if (width < BREAKPOINT_TABLET) return "tablet";
+        return "desktop";
+    }
+
+
+    /**
+     * Wire mobile/tablet chrome controls.
+     */
+    bindChrome() {
+        const navRecipe = document.getElementById("nav-recipe");
+        const navData = document.getElementById("nav-data");
+        const navOps = document.getElementById("nav-ops-fab");
+        const opsClose = document.getElementById("ops-close");
+        const opsScrim = document.getElementById("ops-scrim");
+        const segInput = document.getElementById("seg-input");
+        const segOutput = document.getElementById("seg-output");
+
+        if (navRecipe) {
+            navRecipe.addEventListener("click", () => this.showMobilePane("recipe"));
+        }
+        if (navData) {
+            navData.addEventListener("click", () => this.showMobilePane("data"));
+        }
+        if (navOps) {
+            navOps.addEventListener("click", () => this.toggleOps(true));
+        }
+        if (opsClose) {
+            opsClose.addEventListener("click", () => this.toggleOps(false));
+        }
+        if (opsScrim) {
+            opsScrim.addEventListener("click", () => this.toggleOps(false));
+        }
+        if (segInput) {
+            segInput.addEventListener("click", () => this.showDataSegment("input"));
+        }
+        if (segOutput) {
+            segOutput.addEventListener("click", () => this.showDataSegment("output"));
+        }
+
+        document.addEventListener("keydown", e => {
+            if (e.key === "Escape" && this.opsOpen) {
+                this.toggleOps(false);
+            }
+        });
+
+        const tabletOps = document.getElementById("tablet-ops-toggle");
+        if (tabletOps) {
+            tabletOps.addEventListener("click", () => this.toggleOps(!this.opsOpen));
+        }
+    }
+
+
+    /**
+     * Switch layout mode and manage Split.js.
+     *
+     * @param {"mobile"|"tablet"|"desktop"} mode
+     */
+    applyMode(mode) {
+        if (mode === this.currentMode || !this.root) return;
+
+        const prev = this.currentMode;
+        this.currentMode = mode;
+        this.root.dataset.layout = mode;
+        document.body.dataset.layout = mode;
+
+        this.placeControls(mode);
+
+        if (mode === "desktop") {
+            this.toggleOps(false);
+            if (prev && prev !== "desktop") {
+                this.app.initialiseSplitter();
+            }
+        } else {
+            this.app.destroySplitters();
+            if (mode === "mobile") {
+                this.showMobilePane(this.mobilePane);
+                this.showDataSegment(this.dataSegment);
+            } else {
+                this.showDataSegment("both");
+            }
+        }
+
+        this.app.adjustComponentSizes();
+    }
+
+
+    /**
+     * On mobile the Bake bar must stay visible across panes, so move #controls
+     * out of #recipe (which is display:none when Data is active).
+     *
+     * @param {"mobile"|"tablet"|"desktop"} mode
+     */
+    placeControls(mode) {
+        const controls = document.getElementById("controls");
+        const recipe = document.getElementById("recipe");
+        const workspace = document.getElementById("workspace-wrapper");
+        if (!controls || !recipe || !workspace) return;
+
+        if (mode === "mobile") {
+            if (controls.parentElement !== workspace) {
+                workspace.appendChild(controls);
+            }
+            controls.classList.add("mobile-controls-bar");
+        } else if (controls.parentElement !== recipe) {
+            recipe.appendChild(controls);
+            controls.classList.remove("mobile-controls-bar");
+        }
+    }
+
+
+    /**
+     * @param {"recipe"|"data"} pane
+     */
+    showMobilePane(pane) {
+        this.mobilePane = pane;
+        if (this.root) {
+            this.root.dataset.mobilePane = pane;
+        }
+
+        const navRecipe = document.getElementById("nav-recipe");
+        const navData = document.getElementById("nav-data");
+        if (navRecipe) {
+            navRecipe.classList.toggle("active", pane === "recipe");
+            navRecipe.setAttribute("aria-selected", pane === "recipe" ? "true" : "false");
+        }
+        if (navData) {
+            navData.classList.toggle("active", pane === "data");
+            navData.setAttribute("aria-selected", pane === "data" ? "true" : "false");
+        }
+
+        this.app.adjustComponentSizes();
+    }
+
+
+    /**
+     * @param {"input"|"output"|"both"} segment
+     */
+    showDataSegment(segment) {
+        this.dataSegment = segment === "both" ? "input" : segment;
+        if (this.root) {
+            this.root.dataset.dataSegment = segment;
+        }
+
+        const segInput = document.getElementById("seg-input");
+        const segOutput = document.getElementById("seg-output");
+        if (segInput && segment !== "both") {
+            segInput.classList.toggle("active", segment === "input");
+            segInput.setAttribute("aria-selected", segment === "input" ? "true" : "false");
+        }
+        if (segOutput && segment !== "both") {
+            segOutput.classList.toggle("active", segment === "output");
+            segOutput.setAttribute("aria-selected", segment === "output" ? "true" : "false");
+        }
+
+        this.app.adjustComponentSizes();
+    }
+
+
+    /**
+     * Open / close operations sheet (mobile) or drawer (tablet).
+     *
+     * @param {boolean} open
+     */
+    toggleOps(open) {
+        this.opsOpen = open;
+        if (this.root) {
+            this.root.classList.toggle("ops-open", open);
+        }
+
+        const overlay = document.getElementById("ops-overlay");
+        if (overlay) {
+            overlay.hidden = !open;
+            overlay.setAttribute("aria-hidden", open ? "false" : "true");
+        }
+
+        const ops = document.getElementById("operations");
+        if (ops) {
+            ops.setAttribute("aria-hidden", open || this.currentMode === "desktop" ? "false" : "true");
+            if (open) {
+                const search = document.getElementById("search");
+                if (search) search.focus();
+            }
+        }
+
+        const fab = document.getElementById("nav-ops-fab");
+        if (fab) {
+            fab.setAttribute("aria-expanded", open ? "true" : "false");
+        }
+
+        const tabletOps = document.getElementById("tablet-ops-toggle");
+        if (tabletOps) {
+            tabletOps.setAttribute("aria-expanded", open ? "true" : "false");
+        }
+    }
+
+
+    /**
+     * After adding an operation from the list, keep sheet open for multi-add.
+     */
+    afterOperationAdded() {
+        if (this.currentMode === "mobile") {
+            this.showMobilePane("recipe");
+        }
+    }
+
+
+    /**
+     * @returns {boolean}
+     */
+    isTouchLayout() {
+        return this.currentMode === "mobile" || this.currentMode === "tablet";
+    }
+}
+
+export default ResponsiveLayoutWaiter;