diff --git a/AGENTS.md b/AGENTS.md
index 1aa134e..9e08bb2 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -1,6 +1,6 @@
 # AGENTS.md
 
-Guidance for coding agents working on the Ghost Assembly organisation site,
+Guidance for coding agents working on the Ghost Assembly organization site,
 <https://ghost-assembly.github.io/>. Read `README.md` for the human overview; this file
 holds the rules that are not obvious from the code.
 
@@ -23,7 +23,7 @@ These are deliberate and the test suite enforces most of them.
 - No JavaScript on the page. Theme follows `prefers-color-scheme`; navigation is anchors.
 - No third-party requests from the page. Fonts and images are self-hosted in
   `docs/assets/`. A test fails on any request to another origin.
-- WCAG 2.2 AA. axe runs in both colour schemes with the `wcag2a`, `wcag2aa`,
+- WCAG 2.2 AA. axe runs in both color schemes with the `wcag2a`, `wcag2aa`,
   `wcag21aa`, `wcag22aa` and `best-practice` tags, and must report zero violations.
 - No horizontal scroll at 360px wide.
 - Motion only inside `@media (prefers-reduced-motion: no-preference)`. The hero halo is
@@ -32,7 +32,7 @@ These are deliberate and the test suite enforces most of them.
 
 ## Design rules
 
-- Colour tokens live on `:root` in `docs/style.css`, with a light override under
+- Color tokens live on `:root` in `docs/style.css`, with a light override under
   `prefers-color-scheme: light`. Brand stops are sampled from the logo: cyan `#00a8fc`,
   blue `#2f5afc`, magenta `#d601fc`; paper `#03030a`.
 - `.night` (top bar and hero) re-declares the dark tokens so it stays dark in both
diff --git a/README.md b/README.md
index 4d2e7a8..cd9576b 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 [![ci](https://github.com/Ghost-Assembly/ghost-assembly.github.io/actions/workflows/ci.yml/badge.svg)](https://github.com/Ghost-Assembly/ghost-assembly.github.io/actions/workflows/ci.yml)
 
-The Ghost Assembly organisation site: **<https://ghost-assembly.github.io/>**.
+The Ghost Assembly organization site: **<https://ghost-assembly.github.io/>**.
 
 One hand-written page listing the org's projects, with links to each one's docs and
 source. No framework, no build step and no JavaScript on the page — `docs/` is what
@@ -34,7 +34,7 @@ links. A project with no docs site gets a Source link only.
 Everything in `docs/assets/` except the font is derived from
 `assets/logo-source.png`. After changing the source, run `just assets` to
 regenerate them. The same recipe writes `assets/avatar.png` (512×512 emblem on
-black), the GitHub organisation avatar — it is not published with the site.
+black), the GitHub organization avatar — it is not published with the site.
 
 The heading font is [Orbitron](https://github.com/theleagueof/orbitron), self-hosted
 under the SIL Open Font License (`docs/assets/fonts/OFL.txt`).
diff --git a/design/2026-09-24-org-hub-design.md b/design/2026-09-24-org-hub-design.md
index bfec131..9f75f8e 100644
--- a/design/2026-09-24-org-hub-design.md
+++ b/design/2026-09-24-org-hub-design.md
@@ -68,7 +68,7 @@ Twitter card tags pointing at `og-image.png`, favicon and apple-touch-icon links
   for OG.
 - `emblem.webp` — circular emblem cropped from the top of the logo (header, ~96px).
 - `favicon.png` (32×32) and `apple-touch-icon.png` (180×180, emblem on black).
-- `og-image.png` — 1200×630, logo centred on the near-black background.
+- `og-image.png` — 1200×630, logo centered on the near-black background.
 - The original PNG kept as `assets/logo-source.png` at the repo root (outside `docs/`,
   so it is not published) so derivatives can be regenerated.
 - `assets/avatar.png` — 512×512 emblem on black, for the GitHub org avatar (not published).
diff --git a/docs/style.css b/docs/style.css
index be9a372..8a629cb 100644
--- a/docs/style.css
+++ b/docs/style.css
@@ -1,11 +1,11 @@
 /*
- * Ghost Assembly — organisation site.
+ * Ghost Assembly — organization site.
  *
  * Hand-written, no framework and no build step, like the project docs sites.
  * There is no JavaScript on the page: the theme follows the reader's system
  * setting and navigation is plain anchors.
  *
- * Colours are sampled from the logo. The top band (.night) keeps the dark
+ * Colors are sampled from the logo. The top band (.night) keeps the dark
  * tokens in both schemes, because the logo's silver wordmark and glow only
  * read on black; everything below it follows the reader's scheme.
  */
@@ -185,7 +185,7 @@ a:hover {
     line-height: 0;
 }
 
-/* The halo: the logo's own ring colours, bled out behind it. */
+/* The halo: the logo's own ring colors, bled out behind it. */
 .hero h1::before {
     content: '';
     position: absolute;
diff --git a/package.json b/package.json
index 58188ca..fb64424 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
     "name": "ghost-assembly.github.io",
     "private": true,
-    "description": "The Ghost Assembly organisation site.",
+    "description": "The Ghost Assembly organization site.",
     "license": "MIT",
     "type": "module",
     "engines": {