diff --git a/web/public/favicon.svg b/web/public/favicon.svg
new file mode 100644
index 0000000..f01c1b5
--- /dev/null
+++ b/web/public/favicon.svg
@@ -0,0 +1,19 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128">
+  <!-- substandard sticker: the mark from mark.svg, unchanged, with a
+       rounded-square boundary applied 2 degrees crooked over it. The inner
+       group is a uniform scale/translate of the mark - never edit its
+       angles here; edit mark.svg and re-fit.
+       The frame is sized so its rotated, stroked extent just fits the 128
+       canvas: toolbar tiles are small and Chrome overlays the action badge
+       on top, so any margin here shrinks what survives. -->
+  <rect x="4.5" y="4.5" width="119" height="119" rx="27" fill="#fdfcf9"
+    stroke="#26282b" stroke-width="6" transform="rotate(2 64 64)"/>
+  <g transform="translate(64 64) scale(0.78) translate(-61.5 -75.5)">
+    <rect x="16" y="45" width="28" height="20" rx="8" fill="#8b887f" transform="rotate(-2 30 55)"/>
+    <rect x="52" y="48" width="60" height="20" rx="8" fill="#8b887f" transform="rotate(3 82 58)"/>
+    <g transform="rotate(2 64 88)">
+      <path d="M14,84 q8,-12 16,0 t16,0 t16,0 t16,0 q8,-8 16,4 q6,8 8,14"
+        fill="none" stroke="#d9482b" stroke-width="8" stroke-linecap="round"/>
+    </g>
+  </g>
+</svg>
diff --git a/web/src/layouts/Layout.astro b/web/src/layouts/Layout.astro
index 38ea321..d4fc872 100644
--- a/web/src/layouts/Layout.astro
+++ b/web/src/layouts/Layout.astro
@@ -17,6 +17,7 @@ const { title, description } = Astro.props;
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <title>{title}</title>
     <meta name="description" content={description} />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <link rel="icon" type="image/png" sizes="32x32" href="/icons/icon32.png" />
     {/* Production builds only, so dev servers don't pollute analytics. */}
     {import.meta.env.PROD && <PostHog />}