diff --git a/public/manifest.webmanifest b/public/manifest.webmanifest
index 48e88a4..6c62cc5 100644
--- a/public/manifest.webmanifest
+++ b/public/manifest.webmanifest
@@ -2,23 +2,23 @@
   "name": "EdenText",
   "short_name": "EdenText",
   "description": "A word processor that runs in the browser and saves .odt and .docx. No account, no server: the document never leaves the machine.",
-  "id": "/",
-  "start_url": "/",
-  "scope": "/",
+  "id": "./",
+  "start_url": "./",
+  "scope": "./",
   "display": "standalone",
   "orientation": "any",
   "background_color": "#e6e9eb",
   "theme_color": "#52748b",
   "categories": ["productivity", "utilities"],
   "icons": [
-    { "src": "/favicon.svg", "sizes": "any", "type": "image/svg+xml" },
-    { "src": "/icon-192.png", "sizes": "192x192", "type": "image/png" },
-    { "src": "/icon-512.png", "sizes": "512x512", "type": "image/png" },
-    { "src": "/icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable" }
+    { "src": "favicon.svg", "sizes": "any", "type": "image/svg+xml" },
+    { "src": "icon-192.png", "sizes": "192x192", "type": "image/png" },
+    { "src": "icon-512.png", "sizes": "512x512", "type": "image/png" },
+    { "src": "icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "maskable" }
   ],
   "file_handlers": [
     {
-      "action": "/",
+      "action": "./",
       "accept": {
         "application/vnd.oasis.opendocument.text": [".odt"],
         "application/vnd.oasis.opendocument.text-template": [".ott"],
diff --git a/public/sw.js b/public/sw.js
index 6a19174..13f6100 100644
--- a/public/sw.js
+++ b/public/sw.js
@@ -3,8 +3,9 @@
 // fonts and the WASM speller included, each kept the first time it is asked for.
 
 const CACHE = 'edentext-v1';
-// The entry document under one key, whichever path asked for it.
-const SHELL = '/';
+// The entry document under one key, whichever path asked for it. Relative, so it
+// resolves against this script's own directory — the app root under any base path.
+const SHELL = './';
 
 // The build's asset names carry a content hash, and the entry document is the only
 // place they are written down — so reading them out of it precaches the shell with no
@@ -15,8 +16,8 @@ async function precache(cache) {
   const response = await fetch(SHELL, { cache: 'reload' });
   await cache.put(SHELL, response.clone());
   const html = await response.text();
-  const assets = [...html.matchAll(/(?:src|href)="(\/assets\/[^"]+)"/g)].map((m) => m[1]);
-  await cache.addAll([...new Set(assets), '/favicon.svg', '/manifest.webmanifest']);
+  const assets = [...html.matchAll(/(?:src|href)="(\.?\/assets\/[^"]+)"/g)].map((m) => m[1]);
+  await cache.addAll([...new Set(assets), './favicon.svg', './manifest.webmanifest']);
 }
 
 self.addEventListener('install', (event) => {
diff --git a/src/App.svelte b/src/App.svelte
index e998eda..29c986a 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -1130,7 +1130,7 @@
       <div class="toolbar-stack" bind:this={toolbarStackEl} style="transform: translateX(-{tbScroll}px);">
   <header class:expanded={toolbarExpanded}>
     <button class="logo-btn" onclick={() => (aboutOpen = true)} aria-label={t().about.label} title={t().about.label}>
-      <img src="/EdenText.png" alt="EdenText" class="app-logo" />
+      <img src="EdenText.png" alt="EdenText" class="app-logo" />
     </button>
     <Toolbar editor={activeEditor} tick={activeTick} onManageStyles={openStyleManager} />
     <div class="header-actions">
diff --git a/src/lib/components/AboutDialog.svelte b/src/lib/components/AboutDialog.svelte
index 25f5cee..45f1efd 100644
--- a/src/lib/components/AboutDialog.svelte
+++ b/src/lib/components/AboutDialog.svelte
@@ -40,9 +40,9 @@
       </svg>
     </button>
 
-    <img class="icon" src="/favicon.svg" alt="" aria-hidden="true" />
+    <img class="icon" src="favicon.svg" alt="" aria-hidden="true" />
 
-    <img class="logo" src="/EdenText.png" alt="EdenText" />
+    <img class="logo" src="EdenText.png" alt="EdenText" />
 
     <p class="tagline">{t().about.tagline}</p>
 
diff --git a/src/lib/components/ribbon/Ribbon.svelte b/src/lib/components/ribbon/Ribbon.svelte
index 800d2ea..85869ee 100644
--- a/src/lib/components/ribbon/Ribbon.svelte
+++ b/src/lib/components/ribbon/Ribbon.svelte
@@ -330,7 +330,7 @@
     <UiLanguagePicker />
 
     <button class="rb-logo-btn" onclick={() => run(onAbout)} title={t().about.label} aria-label={t().about.label}>
-      <img src="/favicon.svg" alt="" aria-hidden="true" />
+      <img src="favicon.svg" alt="" aria-hidden="true" />
     </button>
   </div>
 
diff --git a/src/main.ts b/src/main.ts
index f2fd437..51795dc 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -19,7 +19,7 @@ window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', ()
 // build over the one being edited.
 if (import.meta.env.PROD && 'serviceWorker' in navigator) {
     window.addEventListener('load', () => {
-        navigator.serviceWorker.register('/sw.js').catch(() => {});
+        navigator.serviceWorker.register(`${import.meta.env.BASE_URL}sw.js`).catch(() => {});
     });
 }
 
diff --git a/vite.config.ts b/vite.config.ts
index cd2a766..d0556e4 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -4,6 +4,9 @@ import { svelte } from '@sveltejs/vite-plugin-svelte';
 import pkg from './package.json' with { type: 'json' };
 
 export default defineConfig({
+  // Relative asset URLs, so the same build works at the domain root and under a
+  // subpath (GitHub Pages project site). sw.js and the manifest are relative too.
+  base: './',
   plugins: [svelte()],
   define: { __APP_VERSION__: JSON.stringify(pkg.version) },
   // hunspell-asm's ESM chain calls CJS/UMD deps as functions that a bundler