diff --git a/app/controllers/manifests_controller.rb b/app/controllers/manifests_controller.rb
index c151076a..966f6164 100644
--- a/app/controllers/manifests_controller.rb
+++ b/app/controllers/manifests_controller.rb
@@ -6,8 +6,8 @@ class ManifestsController < ApplicationController
   def show
     render json: {
       name:             APP_CONFIG["site_name"],
-      description:      t("about.about.subtitle"),
-      start_url:        root_url(source: "pwa"),
+      description:      t("about.index.subtitle"),
+      start_url:        root_url,
       scope:            root_url,
       display:          "standalone",
       categories:       %w[social],
@@ -37,10 +37,12 @@ class ManifestsController < ApplicationController
   end
 
   def webapp_icons
-    %i[1024 512 384 192 128 96 72 48].map do |size|
+    %i[1024 512 384 192 144 128 96 72 48].map do |size|
       [
-        { src: "/icons/maskable_icon_x#{size}.webp", size: "#{size}x#{size}", type: "image/webp" },
-        { src: "/icons/maskable_icon_x#{size}.png", size: "#{size}x#{size}", type: "image/png" }
+        { src: "/icons/icon_x#{size}.webp", sizes: "#{size}x#{size}", type: "image/webp", purpose: "any" },
+        { src: "/icons/icon_x#{size}.png", sizes: "#{size}x#{size}", type: "image/png", purpose: "any" },
+        { src: "/icons/maskable_icon_x#{size}.webp", sizes: "#{size}x#{size}", type: "image/webp", purpose: "maskable" },
+        { src: "/icons/maskable_icon_x#{size}.png", sizes: "#{size}x#{size}", type: "image/png", purpose: "maskable" }
       ]
     end.flatten
   end
diff --git a/public/icons/icon_x1024.png b/public/icons/icon_x1024.png
new file mode 100644
index 00000000..3bf48a3e
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diff --git a/public/icons/icon_x1024.webp b/public/icons/icon_x1024.webp
new file mode 100644
index 00000000..9c72ad3f
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diff --git a/public/icons/icon_x128.png b/public/icons/icon_x128.png
new file mode 100644
index 00000000..dfb05572
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diff --git a/public/icons/icon_x128.webp b/public/icons/icon_x128.webp
new file mode 100644
index 00000000..c834b7d5
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diff --git a/public/icons/icon_x144.png b/public/icons/icon_x144.png
new file mode 100644
index 00000000..f23a8209
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diff --git a/public/icons/icon_x144.webp b/public/icons/icon_x144.webp
new file mode 100644
index 00000000..6f17b456
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diff --git a/public/icons/icon_x192.png b/public/icons/icon_x192.png
new file mode 100644
index 00000000..02c5c92f
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diff --git a/public/icons/icon_x192.webp b/public/icons/icon_x192.webp
new file mode 100644
index 00000000..866f866d
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diff --git a/public/icons/icon_x384.png b/public/icons/icon_x384.png
new file mode 100644
index 00000000..baceef0f
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diff --git a/public/icons/icon_x384.webp b/public/icons/icon_x384.webp
new file mode 100644
index 00000000..4b771cdd
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diff --git a/public/icons/icon_x48.png b/public/icons/icon_x48.png
new file mode 100644
index 00000000..77093fcd
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diff --git a/public/icons/icon_x48.webp b/public/icons/icon_x48.webp
new file mode 100644
index 00000000..e20794a8
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diff --git a/public/icons/icon_x512.png b/public/icons/icon_x512.png
new file mode 100644
index 00000000..6cf448af
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diff --git a/public/icons/icon_x512.webp b/public/icons/icon_x512.webp
new file mode 100644
index 00000000..bb5981bd
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diff --git a/public/icons/icon_x72.png b/public/icons/icon_x72.png
new file mode 100644
index 00000000..9468c0c6
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diff --git a/public/icons/icon_x72.webp b/public/icons/icon_x72.webp
new file mode 100644
index 00000000..d10e54f7
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diff --git a/public/icons/icon_x96.png b/public/icons/icon_x96.png
new file mode 100644
index 00000000..fe3a4ded
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diff --git a/public/icons/icon_x96.webp b/public/icons/icon_x96.webp
new file mode 100644
index 00000000..96abdb70
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diff --git a/public/icons/maskable_icon_x1024.png b/public/icons/maskable_icon_x1024.png
index 99e22563..34a7834a 100644
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diff --git a/public/icons/maskable_icon_x1024.webp b/public/icons/maskable_icon_x1024.webp
index 9c72ad3f..e69de29b 100644
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diff --git a/public/icons/maskable_icon_x128.png b/public/icons/maskable_icon_x128.png
index 364a2633..36f47fc2 100644
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diff --git a/public/icons/maskable_icon_x128.webp b/public/icons/maskable_icon_x128.webp
index c834b7d5..e69de29b 100644
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diff --git a/public/icons/maskable_icon_x144.png b/public/icons/maskable_icon_x144.png
new file mode 100644
index 00000000..7fb47b2e
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diff --git a/public/icons/maskable_icon_x144.webp b/public/icons/maskable_icon_x144.webp
new file mode 100644
index 00000000..bc19121f
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diff --git a/public/icons/maskable_icon_x192.png b/public/icons/maskable_icon_x192.png
index 431b710f..09697ddc 100644
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diff --git a/public/icons/maskable_icon_x192.webp b/public/icons/maskable_icon_x192.webp
index 866f866d..e69de29b 100644
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diff --git a/public/icons/maskable_icon_x384.png b/public/icons/maskable_icon_x384.png
index 6a63aa51..7eb4cfe5 100644
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diff --git a/public/icons/maskable_icon_x384.webp b/public/icons/maskable_icon_x384.webp
index 4b771cdd..e69de29b 100644
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diff --git a/public/icons/maskable_icon_x48.png b/public/icons/maskable_icon_x48.png
index 130736d5..a3aa4124 100644
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diff --git a/public/icons/maskable_icon_x48.webp b/public/icons/maskable_icon_x48.webp
index e20794a8..e69de29b 100644
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diff --git a/public/icons/maskable_icon_x512.png b/public/icons/maskable_icon_x512.png
index 1667c4a5..cf312b13 100644
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diff --git a/public/icons/maskable_icon_x512.webp b/public/icons/maskable_icon_x512.webp
index bb5981bd..e69de29b 100644
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diff --git a/public/icons/maskable_icon_x72.png b/public/icons/maskable_icon_x72.png
index 3c640f1c..4eb4caa9 100644
Binary files a/public/icons/maskable_icon_x72.png and b/public/icons/maskable_icon_x72.png differ
diff --git a/public/icons/maskable_icon_x72.webp b/public/icons/maskable_icon_x72.webp
index d10e54f7..e69de29b 100644
Binary files a/public/icons/maskable_icon_x72.webp and b/public/icons/maskable_icon_x72.webp differ
diff --git a/public/icons/maskable_icon_x96.png b/public/icons/maskable_icon_x96.png
index 17c8ca66..e1778b91 100644
Binary files a/public/icons/maskable_icon_x96.png and b/public/icons/maskable_icon_x96.png differ
diff --git a/public/icons/maskable_icon_x96.webp b/public/icons/maskable_icon_x96.webp
index 96abdb70..e69de29b 100644
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diff --git a/public/pwa_offline.html b/public/pwa_offline.html
new file mode 100644
index 00000000..1e7fc241
--- /dev/null
+++ b/public/pwa_offline.html
@@ -0,0 +1,148 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>You are offline</title>
+  <meta name="viewport" content="width=device-width,initial-scale=1">
+  <meta name="theme-color" content="#f0edf4">
+  <style>
+    :root {
+      --primary: #5e35b1;
+      --muted: 108, 117, 125;
+      --background: #f0edf4;
+    }
+
+    *, *:before, *:after {
+      box-sizing: border-box;
+    }
+
+    a {
+      color: var(--primary);
+      text-decoration: none;
+    }
+
+    body {
+      padding: 2rem 1rem 1rem 1rem;
+      margin: 0;
+      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
+      background-color: var(--background);
+    }
+
+    .text-primary {
+      color: var(--primary);
+    }
+
+    .text-muted {
+      color: rgb(var(--muted));
+    }
+
+    .text-center {
+      text-align: center;
+    }
+
+    .font-weight-bold {
+      font-weight: bold;
+    }
+
+    .d-none {
+      display: none !important;
+    }
+
+    .links {
+      padding: 0;
+    }
+
+    .links li {
+      display: inline-block;
+    }
+
+    .links li:not(:last-child):after {
+      content: ' • ';
+    }
+
+    .mb-0 {
+      margin-bottom: 0;
+    }
+
+    .mt-0 {
+      margin-top: 0;
+    }
+
+    .error-artwork-container {
+      display:flex;
+      justify-content: center;
+      max-width: 100%;
+    }
+
+    .error-artwork-container picture {
+      display: block;
+      max-width: 100%;
+    }
+
+    .error-artwork-container picture img {
+      max-width: 100%;
+    }
+
+    .error-text-container {
+      text-align: center;
+    }
+
+    @media (min-width: 768px) {
+      body {
+        padding: 3rem 1rem 1rem 1rem;
+      }
+
+      .error-artwork-container picture {
+        width: 576px;
+      }
+    }
+
+    @media (min-width: 992px) {
+      body {
+        padding: 5rem 1rem 3rem 1rem;
+      }
+
+      .error {
+        display: flex;
+        justify-content: center;
+      }
+
+      .error-text-container {
+        align-self: center;
+        text-align: left;
+      }
+    }
+  </style>
+</head>
+<body>
+  <div class="error">
+    <div class="error-artwork-container">
+      <picture>
+        <source
+          srcset="/images/errors/small/404.png 576w,
+                  /images/errors/medium/404.png 768w,
+                  /images/errors/original/404.png 1200w">
+        <img src="/images/errors/small/404.png" alt="A raccoon peeking out of a bin, looking confused" />
+      </picture>
+    </div>
+    <div class="error-text-container">
+      <h1>
+        <small class="text-primary">You are offline</small>
+      </h1>
+      <p>
+        This content is not available offline.
+      </p>
+      <ul class="links">
+        <li>
+          <a href="/">Retry</a>
+        </li>
+      </ul>
+    </div>
+  </div>
+  <script>
+    window.addEventListener('online', () => {
+      window.location.reload();
+    });
+  </script>
+</body>
+</html>
diff --git a/public/service_worker.js b/public/service_worker.js
index 1f13f0f8..3735a89b 100644
--- a/public/service_worker.js
+++ b/public/service_worker.js
@@ -1,3 +1,14 @@
+const OFFLINE_CACHE_NAME = "offline";
+// Bumping this version will force an update of the service worker
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+const OFFLINE_PAGE_VERSION = 1;
+const OFFLINE_CACHE_PATHS = [
+  "/pwa_offline.html",
+  "/images/errors/small/404.png",
+  "/images/errors/medium/404.png",
+  "/images/errors/original/404.png"
+];
+
 self.addEventListener('push', function (event) {
   if (event.data) {
     const notification = event.data.json();
@@ -23,3 +34,31 @@ self.addEventListener('notificationclick', async event => {
     console.warn(`Unhandled notification tag: ${event.notification.tag}`);
   }
 });
+
+self.addEventListener('install', function (event) {
+  event.waitUntil(
+    (async () => {
+      const cache = await caches.open(OFFLINE_CACHE_NAME);
+      await cache.addAll(OFFLINE_CACHE_PATHS);
+    })()
+  );
+  // Immediately activate new versions of the service worker instead of waiting
+  self.skipWaiting();
+});
+
+self.addEventListener('fetch', function (event) {
+  event.respondWith(
+    (async () => {
+      try {
+        // Try to load the resource
+        return await fetch(event.request);
+      } catch (error) {
+        // Show an error page if offline
+        console.log("Fetch failed; returning offline page instead.", error);
+
+        const cache = await caches.open(OFFLINE_CACHE_NAME);
+        return await cache.match(OFFLINE_CACHE_PATHS[0]);
+      }
+    })()
+  );
+});
diff --git a/spec/controllers/manifests_controller_spec.rb b/spec/controllers/manifests_controller_spec.rb
index d22707c4..2dff7e95 100644
--- a/spec/controllers/manifests_controller_spec.rb
+++ b/spec/controllers/manifests_controller_spec.rb
@@ -21,7 +21,7 @@ describe ManifestsController, type: :controller do
       body = JSON.parse(response.body)
 
       expect(body["name"]).to eq("Specspring")
-      expect(body["start_url"]).to eq("http://test.host/?source=pwa")
+      expect(body["start_url"]).to eq("http://test.host/")
       expect(body["scope"]).to eq("http://test.host/")
       expect(body["theme_color"]).to eq("#5e35b1")
     end