diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 163273e6..b9bcf8de 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -84,6 +84,12 @@ jobs:
           cache: npm
       - run: npm install -g npm@11 --no-fund --no-audit
       - run: npm ci --no-fund
+      # Electron 42 dropped the postinstall that used to fetch the binary: it now
+      # downloads on the first `require('electron')`. Doing it HERE keeps that
+      # download out of the first test (where it reads as a mystery timeout) and
+      # out of electron-vite, which asks for the path and never triggers it.
+      - name: Fetch the Electron binary
+        run: node -e "require('electron')"
       # Electron's runtime libraries + Xvfb + a window manager — the same set the
       # Docker test env installs. openbox is NOT optional: unmanaged, the window
       # takes a different width and the diff panes split 571/572 instead of evenly.
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 6931185e..aa67a3bc 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -38,6 +38,12 @@ jobs:
           cache: npm
       - run: npm install -g npm@11 --no-fund --no-audit
       - run: npm ci --no-fund
+      # Electron 42 dropped the postinstall that used to fetch the binary: it now
+      # downloads on the first `require('electron')`. Doing it HERE keeps that
+      # download out of the first test (where it reads as a mystery timeout) and
+      # out of electron-vite, which asks for the path and never triggers it.
+      - name: Fetch the Electron binary
+        run: node -e "require('electron')"
       # Electron's runtime libraries + Xvfb + a window manager — the same set the
       # Docker test env installs. openbox is NOT optional: unmanaged, the window
       # takes a different width and the diff panes split 571/572 instead of evenly.
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 14206197..34374831 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -48,6 +48,11 @@ ENV PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1
 # Linux Electron binaries.
 COPY package.json package-lock.json ./
 RUN npm ci
+# Electron 42 replaced its postinstall with a download on first require(). The
+# volume that shadows node_modules is populated from THIS layer, and the dev
+# server asks electron-vite for the path — which reads path.txt and throws
+# rather than fetching. So the binary is pulled in here, at build time.
+RUN node -e "require('electron')"
 
 COPY . .
 
diff --git a/docs/screenshots/themes/snippet-colour-amber.png b/docs/screenshots/themes/snippet-colour-amber.png
index 66679218..025f38b8 100644
Binary files a/docs/screenshots/themes/snippet-colour-amber.png and b/docs/screenshots/themes/snippet-colour-amber.png differ
diff --git a/docs/screenshots/themes/snippet-colour-beacon.png b/docs/screenshots/themes/snippet-colour-beacon.png
index 8a063f74..87ddf03e 100644
Binary files a/docs/screenshots/themes/snippet-colour-beacon.png and b/docs/screenshots/themes/snippet-colour-beacon.png differ
diff --git a/docs/screenshots/themes/snippet-colour-bloom.png b/docs/screenshots/themes/snippet-colour-bloom.png
index 84f4c082..30bf02b7 100644
Binary files a/docs/screenshots/themes/snippet-colour-bloom.png and b/docs/screenshots/themes/snippet-colour-bloom.png differ
diff --git a/docs/screenshots/themes/snippet-colour-contrast.png b/docs/screenshots/themes/snippet-colour-contrast.png
index 578ebc4b..26664ab4 100644
Binary files a/docs/screenshots/themes/snippet-colour-contrast.png and b/docs/screenshots/themes/snippet-colour-contrast.png differ
diff --git a/docs/screenshots/themes/snippet-colour-dark.png b/docs/screenshots/themes/snippet-colour-dark.png
index cca5ac3f..310ada6b 100644
Binary files a/docs/screenshots/themes/snippet-colour-dark.png and b/docs/screenshots/themes/snippet-colour-dark.png differ
diff --git a/docs/screenshots/themes/snippet-colour-dim.png b/docs/screenshots/themes/snippet-colour-dim.png
index c90fff3b..bb423a69 100644
Binary files a/docs/screenshots/themes/snippet-colour-dim.png and b/docs/screenshots/themes/snippet-colour-dim.png differ
diff --git a/docs/screenshots/themes/snippet-colour-ember.png b/docs/screenshots/themes/snippet-colour-ember.png
index 3ff5853d..9ff24d9f 100644
Binary files a/docs/screenshots/themes/snippet-colour-ember.png and b/docs/screenshots/themes/snippet-colour-ember.png differ
diff --git a/docs/screenshots/themes/snippet-colour-graphite.png b/docs/screenshots/themes/snippet-colour-graphite.png
index 39a12728..417cd906 100644
Binary files a/docs/screenshots/themes/snippet-colour-graphite.png and b/docs/screenshots/themes/snippet-colour-graphite.png differ
diff --git a/docs/screenshots/themes/snippet-colour-light.png b/docs/screenshots/themes/snippet-colour-light.png
index 484227ae..fbe8d597 100644
Binary files a/docs/screenshots/themes/snippet-colour-light.png and b/docs/screenshots/themes/snippet-colour-light.png differ
diff --git a/docs/screenshots/themes/snippet-colour-linen.png b/docs/screenshots/themes/snippet-colour-linen.png
index 06ddffc4..dadd4b34 100644
Binary files a/docs/screenshots/themes/snippet-colour-linen.png and b/docs/screenshots/themes/snippet-colour-linen.png differ
diff --git a/docs/screenshots/themes/snippet-colour-matrix.png b/docs/screenshots/themes/snippet-colour-matrix.png
index b21a84a5..382cb1ca 100644
Binary files a/docs/screenshots/themes/snippet-colour-matrix.png and b/docs/screenshots/themes/snippet-colour-matrix.png differ
diff --git a/docs/screenshots/themes/snippet-colour-meridian.png b/docs/screenshots/themes/snippet-colour-meridian.png
index 0fd5be37..086b4cdc 100644
Binary files a/docs/screenshots/themes/snippet-colour-meridian.png and b/docs/screenshots/themes/snippet-colour-meridian.png differ
diff --git a/docs/screenshots/themes/snippet-colour-neon.png b/docs/screenshots/themes/snippet-colour-neon.png
index f4a66f95..f03b6bbb 100644
Binary files a/docs/screenshots/themes/snippet-colour-neon.png and b/docs/screenshots/themes/snippet-colour-neon.png differ
diff --git a/docs/screenshots/themes/snippet-colour-nord.png b/docs/screenshots/themes/snippet-colour-nord.png
index 207e9510..0ad1ac4e 100644
Binary files a/docs/screenshots/themes/snippet-colour-nord.png and b/docs/screenshots/themes/snippet-colour-nord.png differ
diff --git a/docs/screenshots/themes/snippet-colour-nyan.png b/docs/screenshots/themes/snippet-colour-nyan.png
index 13b978f5..b0ff90bf 100644
Binary files a/docs/screenshots/themes/snippet-colour-nyan.png and b/docs/screenshots/themes/snippet-colour-nyan.png differ
diff --git a/docs/screenshots/themes/snippet-colour-sepia.png b/docs/screenshots/themes/snippet-colour-sepia.png
index faaf6811..d028cd4c 100644
Binary files a/docs/screenshots/themes/snippet-colour-sepia.png and b/docs/screenshots/themes/snippet-colour-sepia.png differ
diff --git a/docs/screenshots/themes/snippet-colour-solar.png b/docs/screenshots/themes/snippet-colour-solar.png
index 4728df1f..fbb5e937 100644
Binary files a/docs/screenshots/themes/snippet-colour-solar.png and b/docs/screenshots/themes/snippet-colour-solar.png differ
diff --git a/docs/screenshots/themes/snippet-colour-tide.png b/docs/screenshots/themes/snippet-colour-tide.png
index ce1f8e39..0aa22e67 100644
Binary files a/docs/screenshots/themes/snippet-colour-tide.png and b/docs/screenshots/themes/snippet-colour-tide.png differ
diff --git a/docs/screenshots/themes/snippet-colour-vector.png b/docs/screenshots/themes/snippet-colour-vector.png
index 6c7c48df..42d50cea 100644
Binary files a/docs/screenshots/themes/snippet-colour-vector.png and b/docs/screenshots/themes/snippet-colour-vector.png differ
diff --git a/docs/screenshots/themes/snippet-colour-volcano.png b/docs/screenshots/themes/snippet-colour-volcano.png
index 05c9668c..3d86a6a8 100644
Binary files a/docs/screenshots/themes/snippet-colour-volcano.png and b/docs/screenshots/themes/snippet-colour-volcano.png differ
diff --git a/package-lock.json b/package-lock.json
index 38e77b3f..b20cacf1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -30,7 +30,7 @@
         "@playwright/test": "^1.61.1",
         "@vitejs/plugin-vue": "^5.2.1",
         "@vitest/coverage-v8": "^4.1.10",
-        "electron": "^39.8.10",
+        "electron": "^42.9.0",
         "electron-builder": "^26.15.3",
         "electron-vite": "^5.0.0",
         "eslint": "^10.7.0",
@@ -522,6 +522,16 @@
         "node": ">=20.19.0"
       }
     },
+    "node_modules/@electron-internal/extract-zip": {
+      "version": "1.0.5",
+      "resolved": "https://registry.npmjs.org/@electron-internal/extract-zip/-/extract-zip-1.0.5.tgz",
+      "integrity": "sha512-+bqFCP98pLI0Tt0XQo1TmlXtwjWchISndDOxCkEcIuUgXWpBnLyRI+2DU+mesvnMMX6L1XDqYNA0lXNDHd/yiA==",
+      "dev": true,
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=22.12.0"
+      }
+    },
     "node_modules/@electron/asar": {
       "version": "3.4.1",
       "resolved": "https://registry.npmjs.org/@electron/asar/-/asar-3.4.1.tgz",
@@ -608,23 +618,50 @@
       }
     },
     "node_modules/@electron/get": {
-      "version": "2.0.3",
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/@electron/get/-/get-5.1.0.tgz",
+      "integrity": "sha512-3kSBtG8ObcTVfXanm5vVJ6UnBLEVmVsRk1M+vGqCuMBV+XLCbJYuWQful+yIy0GQDsSlK0kHEriEHn7SPk4EnA==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
         "debug": "^4.1.1",
-        "env-paths": "^2.2.0",
-        "fs-extra": "^8.1.0",
-        "got": "^11.8.5",
+        "env-paths": "^3.0.0",
+        "graceful-fs": "^4.2.11",
         "progress": "^2.0.3",
-        "semver": "^6.2.0",
+        "semver": "^7.6.3",
         "sumchecker": "^3.0.1"
       },
       "engines": {
-        "node": ">=12"
+        "node": ">=22.12.0"
       },
       "optionalDependencies": {
-        "global-agent": "^3.0.0"
+        "undici": "^7.24.4"
+      }
+    },
+    "node_modules/@electron/get/node_modules/env-paths": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/env-paths/-/env-paths-3.0.0.tgz",
+      "integrity": "sha512-dtJUTepzMW3Lm/NPxRf3wP4642UWhjL2sQxc+ym2YMj1m/H2zDNQOlezafzkHwn6sMstjHTwG6iQQsctDW/b1A==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": "^12.20.0 || ^14.13.1 || >=16.0.0"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/sindresorhus"
+      }
+    },
+    "node_modules/@electron/get/node_modules/semver": {
+      "version": "7.8.5",
+      "resolved": "https://registry.npmjs.org/semver/-/semver-7.8.5.tgz",
+      "integrity": "sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==",
+      "dev": true,
+      "license": "ISC",
+      "bin": {
+        "semver": "bin/semver.js"
+      },
+      "engines": {
+        "node": ">=10"
       }
     },
     "node_modules/@electron/notarize": {
@@ -3333,11 +3370,13 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "22.20.1",
+      "version": "24.13.3",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-24.13.3.tgz",
+      "integrity": "sha512-Dh8vAsV36ig5wa9OX4pXvMc9D3Veibfw2wix0CUwYODLD8nkj9UsLjASr49nPg+2eKzxhBV+v7L8pXvT4e639Q==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "undici-types": "~6.21.0"
+        "undici-types": "~7.18.0"
       }
     },
     "node_modules/@types/responselike": {
@@ -3355,15 +3394,6 @@
       "license": "MIT",
       "optional": true
     },
-    "node_modules/@types/yauzl": {
-      "version": "2.10.3",
-      "dev": true,
-      "license": "MIT",
-      "optional": true,
-      "dependencies": {
-        "@types/node": "*"
-      }
-    },
     "node_modules/@upsetjs/venn.js": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/@upsetjs/venn.js/-/venn.js-2.0.0.tgz",
@@ -4119,14 +4149,6 @@
         "node": "^6 || ^7 || ^8 || ^9 || ^10 || ^11 || ^12 || >=13.7"
       }
     },
-    "node_modules/buffer-crc32": {
-      "version": "0.2.13",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": "*"
-      }
-    },
     "node_modules/buffer-from": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/buffer-from/-/buffer-from-1.1.2.tgz",
@@ -5358,22 +5380,22 @@
       }
     },
     "node_modules/electron": {
-      "version": "39.8.10",
-      "resolved": "https://registry.npmjs.org/electron/-/electron-39.8.10.tgz",
-      "integrity": "sha512-zbYtGPYUI7PzqLAzkk21Rk6j67WN0hxn0Mq/njErZo1d0HSf33is4f8ICI5fMLy5vYe0JtCtM5sYunNOaochSQ==",
+      "version": "42.9.0",
+      "resolved": "https://registry.npmjs.org/electron/-/electron-42.9.0.tgz",
+      "integrity": "sha512-xyKfPbHP43Jx22Z1hItLR4KB5h3/avb5BIX4xaQZ6uPPRY4cQxuHnRVrKCGbSsMa/9zd0bBT4TAVNVuVjYcYtw==",
       "dev": true,
-      "hasInstallScript": true,
       "license": "MIT",
       "dependencies": {
-        "@electron/get": "^2.0.0",
-        "@types/node": "^22.7.7",
-        "extract-zip": "^2.0.1"
+        "@electron-internal/extract-zip": "^1.0.1",
+        "@electron/get": "^5.0.0",
+        "@types/node": "^24.9.0"
       },
       "bin": {
-        "electron": "cli.js"
+        "electron": "cli.js",
+        "install-electron": "install.js"
       },
       "engines": {
-        "node": ">= 12.20.55"
+        "node": ">= 22.12.0"
       }
     },
     "node_modules/electron-builder": {
@@ -6049,25 +6071,6 @@
       "dev": true,
       "license": "Apache-2.0"
     },
-    "node_modules/extract-zip": {
-      "version": "2.0.1",
-      "dev": true,
-      "license": "BSD-2-Clause",
-      "dependencies": {
-        "debug": "^4.1.1",
-        "get-stream": "^5.1.0",
-        "yauzl": "^2.10.0"
-      },
-      "bin": {
-        "extract-zip": "cli.js"
-      },
-      "engines": {
-        "node": ">= 10.17.0"
-      },
-      "optionalDependencies": {
-        "@types/yauzl": "^2.9.1"
-      }
-    },
     "node_modules/fast-deep-equal": {
       "version": "3.1.3",
       "dev": true,
@@ -6102,14 +6105,6 @@
       ],
       "license": "BSD-3-Clause"
     },
-    "node_modules/fd-slicer": {
-      "version": "1.1.0",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "pend": "~1.2.0"
-      }
-    },
     "node_modules/fdir": {
       "version": "6.5.0",
       "resolved": "https://registry.npmjs.org/fdir/-/fdir-6.5.0.tgz",
@@ -6255,19 +6250,6 @@
         "node": ">= 6"
       }
     },
-    "node_modules/fs-extra": {
-      "version": "8.1.0",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "graceful-fs": "^4.2.0",
-        "jsonfile": "^4.0.0",
-        "universalify": "^0.1.0"
-      },
-      "engines": {
-        "node": ">=6 <7 || >=8"
-      }
-    },
     "node_modules/fs.realpath": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
@@ -8135,11 +8117,6 @@
         "url": "https://github.com/sponsors/jet2jet"
       }
     },
-    "node_modules/pend": {
-      "version": "1.2.0",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/picocolors": {
       "version": "1.1.1",
       "license": "ISC"
@@ -9413,7 +9390,9 @@
       }
     },
     "node_modules/undici-types": {
-      "version": "6.21.0",
+      "version": "7.18.2",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.18.2.tgz",
+      "integrity": "sha512-AsuCzffGHJybSaRrmr5eHr81mwJU3kjw6M+uprWvCXiNeN9SOGwQ3Jn8jb8m3Z6izVgknn1R0FTCEAP2QrLY/w==",
       "dev": true,
       "license": "MIT"
     },
@@ -10198,15 +10177,6 @@
         "node": ">=12"
       }
     },
-    "node_modules/yauzl": {
-      "version": "2.10.0",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "buffer-crc32": "~0.2.3",
-        "fd-slicer": "~1.1.0"
-      }
-    },
     "node_modules/yocto-queue": {
       "version": "0.1.0",
       "dev": true,
diff --git a/package.json b/package.json
index f3fc4841..dabf7fdf 100644
--- a/package.json
+++ b/package.json
@@ -57,7 +57,7 @@
     "@playwright/test": "^1.61.1",
     "@vitejs/plugin-vue": "^5.2.1",
     "@vitest/coverage-v8": "^4.1.10",
-    "electron": "^39.8.10",
+    "electron": "^42.9.0",
     "electron-builder": "^26.15.3",
     "electron-vite": "^5.0.0",
     "eslint": "^10.7.0",
@@ -75,7 +75,7 @@
     "esbuild@0.25.12": true,
     "fsevents@2.3.3": true,
     "fsevents@2.3.2": true,
-    "electron@39.8.10": true,
-    "vue-demi@0.14.10": true
+    "vue-demi@0.14.10": true,
+    "electron@42.9.0": true
   }
 }