diff --git a/web/src/lib/components/Sidebar.svelte b/web/src/lib/components/Sidebar.svelte
index 806ea7a..99374ae 100644
--- a/web/src/lib/components/Sidebar.svelte
+++ b/web/src/lib/components/Sidebar.svelte
@@ -1,5 +1,5 @@
 <script>
-	import { app } from '$lib/stores.svelte.js';
+	import { app, sidebar } from '$lib/stores.svelte.js';
 	import { api } from '$lib/api.js';
 	import { page } from '$app/stores';
 	import { goto } from '$app/navigation';
@@ -42,6 +42,32 @@
 	);
 	let current = $derived($page.url.pathname);
 
+	// --- resizing -------------------------------------------------------------------
+
+	let resizing = $state(false);
+
+	/**
+	 * Pointer events rather than mouse events, so a trackpad, a mouse and a stylus
+	 * all work. Capturing the pointer means the drag keeps following even when it
+	 * leaves the handle, which at 4px wide it does constantly.
+	 */
+	function startResize(event) {
+		event.preventDefault();
+		resizing = true;
+		event.currentTarget.setPointerCapture(event.pointerId);
+	}
+
+	function onResize(event) {
+		if (!resizing) return;
+		sidebar.setWidth(event.clientX);
+	}
+
+	function endResize(event) {
+		if (!resizing) return;
+		resizing = false;
+		event.currentTarget.releasePointerCapture?.(event.pointerId);
+	}
+
 	// --- reordering ---------------------------------------------------------------
 
 	let draggingId = $state(null);
@@ -241,6 +267,29 @@
 			<span class="signout">Log ud</span>
 		</button>
 	</div>
+	<!-- Also a slider for the keyboard: arrow keys move it, and Home puts it back.
+	     A drag handle with no keyboard equivalent is a setting some people simply
+	     cannot reach. -->
+	<div
+		class="resize"
+		class:resizing
+		role="separator"
+		aria-orientation="vertical"
+		aria-label="Bredde på sidebjælken"
+		tabindex="0"
+		onpointerdown={startResize}
+		onpointermove={onResize}
+		onpointerup={endResize}
+		onpointercancel={endResize}
+		ondblclick={() => sidebar.reset()}
+		onkeydown={(e) => {
+			if (e.key === 'ArrowLeft') sidebar.setWidth(sidebar.width - 16);
+			else if (e.key === 'ArrowRight') sidebar.setWidth(sidebar.width + 16);
+			else if (e.key === 'Home') sidebar.reset();
+			else return;
+			e.preventDefault();
+		}}
+	></div>
 </nav>
 
 <style>
@@ -255,6 +304,45 @@
 		border-right: 1px solid var(--line);
 		overflow-y: auto;
 		padding-left: max(var(--s3), env(safe-area-inset-left));
+		position: relative;
+	}
+
+	/* Sits on the border, wider than it looks: a 1px target is a target you miss.
+	   The visible line stays the border; this only widens what the pointer hits. */
+	.resize {
+		position: absolute;
+		top: 0;
+		bottom: 0;
+		right: -3px;
+		width: 7px;
+		cursor: col-resize;
+		z-index: 10;
+	}
+
+	.resize::after {
+		content: '';
+		position: absolute;
+		inset: 0 3px;
+		background: var(--accent);
+		opacity: 0;
+		transition: opacity var(--fast) var(--ease);
+	}
+
+	.resize:hover::after,
+	.resize:focus-visible::after,
+	.resize.resizing::after {
+		opacity: 1;
+	}
+
+	.resize:focus-visible {
+		outline: none;
+	}
+
+	@media (max-width: 820px) {
+		/* The drawer has a fixed width and no room to drag against. */
+		.resize {
+			display: none;
+		}
 	}
 
 	.brand {
diff --git a/web/src/lib/stores.svelte.js b/web/src/lib/stores.svelte.js
index bb86e21..34c8af9 100644
--- a/web/src/lib/stores.svelte.js
+++ b/web/src/lib/stores.svelte.js
@@ -286,6 +286,58 @@ class AppState {
 
 export const app = new AppState();
 
+/**
+ * How wide the sidebar is, and whether it is showing at all.
+ *
+ * Kept in localStorage rather than on the account: it is a property of the
+ * screen you are sitting at, not of you. The same person on a laptop and on a
+ * wide monitor wants different answers, and syncing it would make one of those
+ * two wrong every time they switch.
+ */
+const SIDEBAR_MIN = 200;
+const SIDEBAR_MAX = 480;
+const SIDEBAR_DEFAULT = 268;
+
+function storedNumber(key, fallback) {
+	if (typeof localStorage === 'undefined') return fallback;
+	const raw = Number(localStorage.getItem(key));
+	return Number.isFinite(raw) && raw > 0 ? raw : fallback;
+}
+
+class SidebarLayout {
+	width = $state(storedNumber('verdande:sidebar-width', SIDEBAR_DEFAULT));
+	collapsed = $state(
+		typeof localStorage !== 'undefined' && localStorage.getItem('verdande:sidebar-collapsed') === '1'
+	);
+
+	setWidth(px) {
+		// Clamped here rather than in the drag handler, so every caller gets the
+		// same rule and a stored value from an older build cannot make the
+		// sidebar unusably narrow.
+		this.width = Math.round(Math.min(SIDEBAR_MAX, Math.max(SIDEBAR_MIN, px)));
+		this.#save('verdande:sidebar-width', String(this.width));
+	}
+
+	toggle() {
+		this.collapsed = !this.collapsed;
+		this.#save('verdande:sidebar-collapsed', this.collapsed ? '1' : '0');
+	}
+
+	reset() {
+		this.setWidth(SIDEBAR_DEFAULT);
+	}
+
+	#save(key, value) {
+		try {
+			localStorage.setItem(key, value);
+		} catch {
+			// Private browsing; the choice simply will not persist.
+		}
+	}
+}
+
+export const sidebar = new SidebarLayout();
+
 /** Theme, kept in localStorage and applied to the document element. */
 export const theme = {
 	get current() {
diff --git a/web/src/routes/+layout.svelte b/web/src/routes/+layout.svelte
index 7ba6b35..a711881 100644
--- a/web/src/routes/+layout.svelte
+++ b/web/src/routes/+layout.svelte
@@ -1,6 +1,6 @@
 <script>
 	import '../app.css';
-	import { app, theme } from '$lib/stores.svelte.js';
+	import { app, theme, sidebar } from '$lib/stores.svelte.js';
 	import { goto } from '$app/navigation';
 	import { page } from '$app/stores';
 	import Sidebar from '$lib/components/Sidebar.svelte';
@@ -66,11 +66,20 @@
 {:else if !app.user}
 	<SignIn />
 {:else}
-	<div class="shell" class:sidebar-open={sidebarOpen}>
+	<div
+		class="shell"
+		class:sidebar-open={sidebarOpen}
+		class:sidebar-collapsed={sidebar.collapsed}
+		style="--sidebar-width: {sidebar.width}px"
+	>
 		<Sidebar onnavigate={() => (sidebarOpen = false)} />
 
 		<main>
 			<header class="topbar">
+				<!-- Two controls, not one: on a phone the sidebar is a drawer that
+				     opens over the page, on a desktop it is a column that folds away.
+				     Same words, different actions, so each is shown only where it
+				     applies. -->
 				<button
 					class="menu"
 					onclick={() => (sidebarOpen = !sidebarOpen)}
@@ -82,6 +91,19 @@
 					</svg>
 				</button>
 
+				<button
+					class="fold"
+					onclick={() => sidebar.toggle()}
+					aria-label={sidebar.collapsed ? 'Vis sidebjælken' : 'Skjul sidebjælken'}
+					aria-pressed={sidebar.collapsed}
+					title={sidebar.collapsed ? 'Vis sidebjælken' : 'Skjul sidebjælken'}
+				>
+					<svg viewBox="0 0 24 24" aria-hidden="true">
+						<rect x="3" y="4" width="18" height="16" rx="2" />
+						<path d="M9 4v16" />
+					</svg>
+				</button>
+
 				<button class="search" onclick={() => (paletteOpen = true)}>
 					<span>Søg</span>
 					<kbd>⌘K</kbd>
@@ -173,7 +195,32 @@
 		color: var(--ink-muted);
 	}
 
+	.fold {
+		display: grid;
+		width: 32px;
+		height: 32px;
+		place-items: center;
+		border-radius: var(--radius);
+		color: var(--ink-faint);
+		transition: color var(--fast) var(--ease);
+	}
+
+	.fold:hover {
+		color: var(--ink);
+	}
+
+	/* Folded away rather than merely narrow: width 0 with the border gone, so
+	   nothing of it is left to catch the eye. */
+	.shell.sidebar-collapsed :global(.sidebar) {
+		width: 0;
+		padding-left: 0;
+		padding-right: 0;
+		border-right: 0;
+		overflow: hidden;
+	}
+
 	.menu svg,
+	.fold svg,
 	.theme svg {
 		width: 18px;
 		height: 18px;
@@ -277,6 +324,11 @@
 			display: grid;
 		}
 
+		/* The drawer is the whole answer here; folding a drawer means nothing. */
+		.fold {
+			display: none;
+		}
+
 		.scrim {
 			display: block;
 		}
@@ -292,5 +344,15 @@
 		.shell.sidebar-open :global(.sidebar) {
 			transform: translateX(0);
 		}
+
+		/* A collapsed desktop sidebar must not follow you to a phone, where the
+		   drawer would then open to nothing. */
+		.shell.sidebar-collapsed :global(.sidebar) {
+			width: var(--sidebar-width);
+			padding-left: max(var(--s3), env(safe-area-inset-left));
+			padding-right: var(--s3);
+			border-right: 1px solid var(--line);
+			overflow-y: auto;
+		}
 	}
 </style>