diff --git a/lib/metalsmith.js b/lib/metalsmith.js
index 0ab967404b..70f6d74b01 100644
--- a/lib/metalsmith.js
+++ b/lib/metalsmith.js
@@ -13,7 +13,7 @@ const permalinks = require('metalsmith-permalinks') // apply a permalink pattern
 const canonical = require('metalsmith-canonical') // add a canonical url property to pages
 
 const sass = require('@metalsmith/sass') // convert Sass files to CSS using Dart Sass
-const postcss = require('metalsmith-postcss')
+const postcss = require('@metalsmith/postcss')
 
 const rollup = require('metalsmith-rollup') // used to build GOV.UK Frontend JavaScript
 const resolve = require('rollup-plugin-node-resolve') // rollup plugin to resolve node_modules
diff --git a/package-lock.json b/package-lock.json
index 0104326f2f..a45243f8dd 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8,6 +8,7 @@
       "hasInstallScript": true,
       "license": "MIT",
       "dependencies": {
+        "@metalsmith/postcss": "^5.0.0",
         "acorn": "^6.4.1",
         "autoprefixer": "^9.5.1",
         "clipboard": "^2.0.4",
@@ -18,9 +19,8 @@
         "highlight.js": "^10.4.1",
         "html5shiv": "^3.7.3",
         "lunr": "^2.3.6",
-        "metalsmith-postcss": "^4.2.0",
         "modernizr": "^3.7.1",
-        "postcss": "^6.0.23",
+        "postcss": "^8.4.14",
         "sass-export": "^2.1.0",
         "serve-static": "^1.13.2",
         "slugger": "^1.0.1"
@@ -1364,29 +1364,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/@jest/core/node_modules/micromatch": {
-      "version": "4.0.4",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "braces": "^3.0.1",
-        "picomatch": "^2.2.3"
-      },
-      "engines": {
-        "node": ">=8.6"
-      }
-    },
-    "node_modules/@jest/core/node_modules/picomatch": {
-      "version": "2.3.0",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/@jest/core/node_modules/rimraf": {
       "version": "3.0.2",
       "dev": true,
@@ -1733,29 +1710,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/@jest/transform/node_modules/micromatch": {
-      "version": "4.0.4",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "braces": "^3.0.1",
-        "picomatch": "^2.2.3"
-      },
-      "engines": {
-        "node": ">=8.6"
-      }
-    },
-    "node_modules/@jest/transform/node_modules/picomatch": {
-      "version": "2.3.0",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/@jest/transform/node_modules/slash": {
       "version": "3.0.0",
       "dev": true,
@@ -1915,6 +1869,18 @@
         "@jridgewell/sourcemap-codec": "^1.4.10"
       }
     },
+    "node_modules/@metalsmith/postcss": {
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/@metalsmith/postcss/-/postcss-5.0.0.tgz",
+      "integrity": "sha512-sMjGcerJMi76m9tFac/3I+20dvLHkmYfMnYFDnLrWyWNSerqNjS/vdI81sSQRvAhNRjr0QK+F+YBOKguBIcdUA==",
+      "engines": {
+        "node": ">=12"
+      },
+      "peerDependencies": {
+        "metalsmith": "^2.4.1",
+        "postcss": "^5.0.4 || ^6.0.0 || ^7.0.0 || ^8.0.0"
+      }
+    },
     "node_modules/@metalsmith/sass": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/@metalsmith/sass/-/sass-1.0.0.tgz",
@@ -2885,14 +2851,6 @@
         "url": "https://opencollective.com/browserslist"
       }
     },
-    "node_modules/browserslist/node_modules/caniuse-lite": {
-      "version": "1.0.30001228",
-      "license": "CC-BY-4.0",
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/browserslist"
-      }
-    },
     "node_modules/browserslist/node_modules/electron-to-chromium": {
       "version": "1.3.736",
       "license": "ISC"
@@ -2987,8 +2945,19 @@
       }
     },
     "node_modules/caniuse-lite": {
-      "version": "1.0.30000962",
-      "license": "CC-BY-4.0"
+      "version": "1.0.30001367",
+      "resolved": "https://registry.npmjs.org/caniuse-lite/-/caniuse-lite-1.0.30001367.tgz",
+      "integrity": "sha512-XDgbeOHfifWV3GEES2B8rtsrADx4Jf+juKX2SICJcaUhjYBO3bR96kvEIHa15VU6ohtOhBZuPGGYGbXMRn0NCw==",
+      "funding": [
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/browserslist"
+        },
+        {
+          "type": "tidelift",
+          "url": "https://tidelift.com/funding/github/npm/caniuse-lite"
+        }
+      ]
     },
     "node_modules/caseless": {
       "version": "0.12.0",
@@ -3212,15 +3181,6 @@
         "url": "https://github.com/chalk/wrap-ansi?sponsor=1"
       }
     },
-    "node_modules/clone": {
-      "version": "2.1.2",
-      "resolved": "https://registry.npmjs.org/clone/-/clone-2.1.2.tgz",
-      "integrity": "sha1-G39Ln1kfHo+DZwQBYANFoCiHQ18=",
-      "dev": true,
-      "engines": {
-        "node": ">=0.8"
-      }
-    },
     "node_modules/clone-deep": {
       "version": "0.2.4",
       "dev": true,
@@ -3245,49 +3205,6 @@
         "node": ">= 0.12.0"
       }
     },
-    "node_modules/co-from-stream": {
-      "version": "0.0.0",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "co-read": "0.0.1"
-      }
-    },
-    "node_modules/co-fs-extra": {
-      "version": "1.2.1",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "co-from-stream": "~0.0.0",
-        "fs-extra": "~0.26.5",
-        "thunkify-wrap": "~1.0.4"
-      }
-    },
-    "node_modules/co-fs-extra/node_modules/fs-extra": {
-      "version": "0.26.7",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "graceful-fs": "^4.1.2",
-        "jsonfile": "^2.1.0",
-        "klaw": "^1.0.0",
-        "path-is-absolute": "^1.0.0",
-        "rimraf": "^2.2.8"
-      }
-    },
-    "node_modules/co-fs-extra/node_modules/jsonfile": {
-      "version": "2.4.0",
-      "dev": true,
-      "license": "MIT",
-      "optionalDependencies": {
-        "graceful-fs": "^4.1.6"
-      }
-    },
-    "node_modules/co-read": {
-      "version": "0.0.1",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/code-point-at": {
       "version": "1.1.0",
       "license": "MIT",
@@ -3428,7 +3345,6 @@
     },
     "node_modules/cross-spawn": {
       "version": "7.0.3",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "path-key": "^3.1.0",
@@ -3441,7 +3357,6 @@
     },
     "node_modules/cross-spawn/node_modules/path-key": {
       "version": "3.1.1",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">=8"
@@ -3449,7 +3364,6 @@
     },
     "node_modules/cross-spawn/node_modules/shebang-command": {
       "version": "2.0.0",
-      "dev": true,
       "license": "MIT",
       "dependencies": {
         "shebang-regex": "^3.0.0"
@@ -3460,7 +3374,6 @@
     },
     "node_modules/cross-spawn/node_modules/shebang-regex": {
       "version": "3.0.0",
-      "dev": true,
       "license": "MIT",
       "engines": {
         "node": ">=8"
@@ -3468,7 +3381,6 @@
     },
     "node_modules/cross-spawn/node_modules/which": {
       "version": "2.0.2",
-      "dev": true,
       "license": "ISC",
       "dependencies": {
         "isexe": "^2.0.0"
@@ -3839,14 +3751,6 @@
       "version": "7.0.3",
       "license": "MIT"
     },
-    "node_modules/enable": {
-      "version": "1.3.2",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">= 0.10.0"
-      }
-    },
     "node_modules/encodeurl": {
       "version": "1.0.2",
       "license": "MIT",
@@ -6346,7 +6250,6 @@
     },
     "node_modules/is-utf8": {
       "version": "0.2.1",
-      "dev": true,
       "license": "MIT"
     },
     "node_modules/is-wsl": {
@@ -6867,29 +6770,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/jest-config/node_modules/micromatch": {
-      "version": "4.0.4",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "braces": "^3.0.1",
-        "picomatch": "^2.2.3"
-      },
-      "engines": {
-        "node": ">=8.6"
-      }
-    },
-    "node_modules/jest-config/node_modules/picomatch": {
-      "version": "2.3.0",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/jest-config/node_modules/supports-color": {
       "version": "7.2.0",
       "dev": true,
@@ -7228,29 +7108,6 @@
       "dev": true,
       "license": "ISC"
     },
-    "node_modules/jest-haste-map/node_modules/micromatch": {
-      "version": "4.0.4",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "braces": "^3.0.1",
-        "picomatch": "^2.2.3"
-      },
-      "engines": {
-        "node": ">=8.6"
-      }
-    },
-    "node_modules/jest-haste-map/node_modules/picomatch": {
-      "version": "2.3.0",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/jest-jasmine2": {
       "version": "27.2.3",
       "dev": true,
@@ -7559,29 +7416,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/jest-message-util/node_modules/micromatch": {
-      "version": "4.0.4",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "braces": "^3.0.1",
-        "picomatch": "^2.2.3"
-      },
-      "engines": {
-        "node": ">=8.6"
-      }
-    },
-    "node_modules/jest-message-util/node_modules/picomatch": {
-      "version": "2.3.0",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/jest-message-util/node_modules/slash": {
       "version": "3.0.0",
       "dev": true,
@@ -8410,17 +8244,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/jest-util/node_modules/picomatch": {
-      "version": "2.3.0",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/jest-util/node_modules/supports-color": {
       "version": "7.2.0",
       "dev": true,
@@ -9176,14 +8999,6 @@
         "node": ">=0.10.0"
       }
     },
-    "node_modules/klaw": {
-      "version": "1.3.1",
-      "dev": true,
-      "license": "MIT",
-      "optionalDependencies": {
-        "graceful-fs": "^4.1.9"
-      }
-    },
     "node_modules/kleur": {
       "version": "3.0.3",
       "dev": true,
@@ -9580,23 +9395,19 @@
       "license": "MIT"
     },
     "node_modules/metalsmith": {
-      "version": "2.4.2",
-      "resolved": "https://registry.npmjs.org/metalsmith/-/metalsmith-2.4.2.tgz",
-      "integrity": "sha512-HS/MRADloJS3+O5V/+4f/khBkwtdYUQFWEGqeviLT/7wNgHWknMiIflV99JeYzj0hbw+L0aTb2spPlnWW4/Adg==",
-      "dev": true,
+      "version": "2.5.0",
+      "resolved": "https://registry.npmjs.org/metalsmith/-/metalsmith-2.5.0.tgz",
+      "integrity": "sha512-tBFpCMq8t/ZeD8qbvyWSLjyW7aO8RJYeFSk8LyclgHYaeMWiSPrMxXc3NORVCJ3iG17aRxuL/+nla58Qq3DBcQ==",
+      "hasInstallScript": true,
       "dependencies": {
-        "chalk": "^4.1.2",
-        "clone": "^2.1.2",
-        "co-fs-extra": "^1.2.1",
         "commander": "^6.2.1",
         "cross-spawn": "^7.0.3",
+        "debug": "^4.3.3",
         "gray-matter": "^4.0.3",
         "is-utf8": "~0.2.0",
-        "micromatch": "^4.0.4",
+        "micromatch": "^4.0.5",
         "rimraf": "^3.0.2",
         "stat-mode": "^1.0.0",
-        "thunkify": "^2.1.2",
-        "unyield": "0.0.1",
         "ware": "^1.3.0"
       },
       "bin": {
@@ -9604,7 +9415,7 @@
         "metalsmith": "bin/metalsmith"
       },
       "engines": {
-        "node": ">=8.6"
+        "node": ">=12"
       }
     },
     "node_modules/metalsmith-assets": {
@@ -9852,16 +9663,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/metalsmith-postcss": {
-      "version": "4.2.0",
-      "license": "MIT",
-      "dependencies": {
-        "minimatch": "^3.0.4"
-      },
-      "peerDependencies": {
-        "postcss": "^5.0.4 || ^6.0.0"
-      }
-    },
     "node_modules/metalsmith-rollup": {
       "version": "2.0.0",
       "dev": true,
@@ -9909,63 +9710,34 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/metalsmith/node_modules/ansi-styles": {
-      "version": "4.3.0",
-      "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
-      "integrity": "sha512-zbB9rCJAT1rbjiVDb2hqKFHNYLxgtk8NURxZ3IZwD3F6NtxbXZQCnnSi1Lkx+IDohdPlFp222wVALIheZJQSEg==",
-      "dev": true,
-      "dependencies": {
-        "color-convert": "^2.0.1"
-      },
+    "node_modules/metalsmith/node_modules/commander": {
+      "version": "6.2.1",
+      "resolved": "https://registry.npmjs.org/commander/-/commander-6.2.1.tgz",
+      "integrity": "sha512-U7VdrJFnJgo4xjrHpTzu0yrHPGImdsmD95ZlgYSEajAn2JKzDhDTPG9kBTefmObL2w/ngeZnilk+OV9CG3d7UA==",
       "engines": {
-        "node": ">=8"
-      },
-      "funding": {
-        "url": "https://github.com/chalk/ansi-styles?sponsor=1"
+        "node": ">= 6"
       }
     },
-    "node_modules/metalsmith/node_modules/chalk": {
-      "version": "4.1.2",
-      "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
-      "integrity": "sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==",
-      "dev": true,
+    "node_modules/metalsmith/node_modules/debug": {
+      "version": "4.3.4",
+      "resolved": "https://registry.npmjs.org/debug/-/debug-4.3.4.tgz",
+      "integrity": "sha512-PRWFHuSU3eDtQJPvnNY7Jcket1j0t5OuOsFzPPzsekD52Zl8qUfFIPEiswXqIvHWGVHOgX+7G/vCNNhehwxfkQ==",
       "dependencies": {
-        "ansi-styles": "^4.1.0",
-        "supports-color": "^7.1.0"
+        "ms": "2.1.2"
       },
       "engines": {
-        "node": ">=10"
-      },
-      "funding": {
-        "url": "https://github.com/chalk/chalk?sponsor=1"
-      }
-    },
-    "node_modules/metalsmith/node_modules/color-convert": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-2.0.1.tgz",
-      "integrity": "sha512-RRECPsj7iu/xb5oKYcsFHSppFNnsj/52OVTRKb4zP5onXwVF3zVmmToNcOfGC+CRDpfK/U584fMg38ZHCaElKQ==",
-      "dev": true,
-      "dependencies": {
-        "color-name": "~1.1.4"
+        "node": ">=6.0"
       },
-      "engines": {
-        "node": ">=7.0.0"
-      }
-    },
-    "node_modules/metalsmith/node_modules/commander": {
-      "version": "6.2.1",
-      "resolved": "https://registry.npmjs.org/commander/-/commander-6.2.1.tgz",
-      "integrity": "sha512-U7VdrJFnJgo4xjrHpTzu0yrHPGImdsmD95ZlgYSEajAn2JKzDhDTPG9kBTefmObL2w/ngeZnilk+OV9CG3d7UA==",
-      "dev": true,
-      "engines": {
-        "node": ">= 6"
+      "peerDependenciesMeta": {
+        "supports-color": {
+          "optional": true
+        }
       }
     },
     "node_modules/metalsmith/node_modules/glob": {
       "version": "7.2.0",
       "resolved": "https://registry.npmjs.org/glob/-/glob-7.2.0.tgz",
       "integrity": "sha512-lmLf6gtyrPq8tTjSmrO94wBeQbFR3HbLHbuyD69wuyQkImp2hWqMGB47OX65FBkPffO641IP9jWa1z4ivqG26Q==",
-      "dev": true,
       "dependencies": {
         "fs.realpath": "^1.0.0",
         "inflight": "^1.0.4",
@@ -9981,20 +9753,15 @@
         "url": "https://github.com/sponsors/isaacs"
       }
     },
-    "node_modules/metalsmith/node_modules/has-flag": {
-      "version": "4.0.0",
-      "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-4.0.0.tgz",
-      "integrity": "sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==",
-      "dev": true,
-      "engines": {
-        "node": ">=8"
-      }
+    "node_modules/metalsmith/node_modules/ms": {
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.2.tgz",
+      "integrity": "sha512-sGkPx+VjMtmA6MX27oA4FBFELFCZZ4S4XqeGOXCv68tT+jb3vk/RyaKWP0PTKyWtmLSM0b+adUTEvbs1PEaH2w=="
     },
     "node_modules/metalsmith/node_modules/rimraf": {
       "version": "3.0.2",
       "resolved": "https://registry.npmjs.org/rimraf/-/rimraf-3.0.2.tgz",
       "integrity": "sha512-JZkJMZkAGFFPP2YqXZXPbMlMBgsxzE8ILs4lMIX/2o0L9UBw9O/Y3o6wFw/i9YLapcUJWwqbi3kdxIPdC62TIA==",
-      "dev": true,
       "dependencies": {
         "glob": "^7.1.3"
       },
@@ -10009,46 +9776,22 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/stat-mode/-/stat-mode-1.0.0.tgz",
       "integrity": "sha512-jH9EhtKIjuXZ2cWxmXS8ZP80XyC3iasQxMDV8jzhNJpfDb7VbQLVW4Wvsxz9QZvzV+G4YoSfBUVKDOyxLzi/sg==",
-      "dev": true,
       "engines": {
         "node": ">= 6"
       }
     },
-    "node_modules/metalsmith/node_modules/supports-color": {
-      "version": "7.2.0",
-      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
-      "integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
-      "dev": true,
-      "dependencies": {
-        "has-flag": "^4.0.0"
-      },
-      "engines": {
-        "node": ">=8"
-      }
-    },
     "node_modules/micromatch": {
-      "version": "4.0.4",
-      "dev": true,
-      "license": "MIT",
+      "version": "4.0.5",
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-          "integrity": "sha512-jH9EhtKIjuXZ2cWxmXS8ZP80XyC3iasQxMDV8jzhNJpfDb7VbQLVW4Wvsxz9QZvzV+G4YoSfBUVKDOyxLzi/sg==",
-          "dev": true
-        },
-        "supports-color": {
-          "version": "7.2.0",
-          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
-          "integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
-          "dev": true,
-          "requires": {
-            "has-flag": "^4.0.0"
-          }
+          "integrity": "sha512-jH9EhtKIjuXZ2cWxmXS8ZP80XyC3iasQxMDV8jzhNJpfDb7VbQLVW4Wvsxz9QZvzV+G4YoSfBUVKDOyxLzi/sg=="
         }
       }
     },
@@ -20898,12 +20442,6 @@
         }
       }
     },
-    "metalsmith-postcss": {
-      "version": "4.2.0",
-      "requires": {
-        "minimatch": "^3.0.4"
-      }
-    },
     "metalsmith-rollup": {
       "version": "2.0.0",
       "dev": true,
@@ -20938,17 +20476,12 @@
       }
     },
     "micromatch": {
-      "version": "4.0.4",
-      "dev": true,
+      "version": "4.0.5",
+      "resolved": "https://registry.npmjs.org/micromatch/-/micromatch-4.0.5.tgz",
+      "integrity": "sha512-DMy+ERcEW2q8Z2Po+WNXuw3c5YaUSFjAO5GsJqfEl7UjvtIuFKO6ZrKvcItdy98dwFI2N1tg3zNIdKaQT+aNdA==",
       "requires": {
-        "braces": "^3.0.1",
-        "picomatch": "^2.2.3"
-      },
-      "dependencies": {
-        "picomatch": {
-          "version": "2.3.0",
-          "dev": true
-        }
+        "braces": "^3.0.2",
+        "picomatch": "^2.3.1"
       }
     },
     "mime": {
@@ -21147,6 +20680,11 @@
     "mute-stream": {
       "version": "0.0.7"
     },
+    "nanoid": {
+      "version": "3.3.4",
+      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.4.tgz",
+      "integrity": "sha512-MqBkQh/OHTS2egovRtLk45wEyNXwF+cokD+1YPf9u5VfJiRdAiRwB2froX5Co9Rh20xs4siNPm8naNotSD6RBw=="
+    },
     "natural-compare": {
       "version": "1.4.0"
     },
@@ -21451,8 +20989,15 @@
       "version": "2.1.0",
       "dev": true
     },
+    "picocolors": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.0.0.tgz",
+      "integrity": "sha512-1fygroTLlHu66zi26VoTDv8yRgm0Fccecssto+MhsZ0D/DGW2sm8E8AjW7NU5VVTRt5GxbeZ5qBuJr+HyLYkjQ=="
+    },
     "picomatch": {
-      "version": "2.2.2"
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.3.1.tgz",
+      "integrity": "sha512-JU3teHTNjmE2VCGFzuY8EXzCDVwEqB2a8fsIvwaStHhAWJEeVd1o1QD80CU6+ZdEXXSLbSsuLwJjkCBWqRQUVA=="
     },
     "pify": {
       "version": "2.3.0",
@@ -21606,36 +21151,13 @@
       }
     },
     "postcss": {
-      "version": "6.0.23",
+      "version": "8.4.14",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.14.tgz",
+      "integrity": "sha512-E398TUmfAYFPBSdzgeieK2Y1+1cpdxJx8yXbK/m57nRhKSmk1GB2tO4lbLBtlkfPQTDKfe4Xqv1ASWPpayPEig==",
       "requires": {
-        "chalk": "^2.4.1",
-        "source-map": "^0.6.1",
-        "supports-color": "^5.4.0"
-      },
-      "dependencies": {
-        "ansi-styles": {
-          "version": "3.2.1",
-          "requires": {
-            "color-convert": "^1.9.0"
-          }
-        },
-        "chalk": {
-          "version": "2.4.2",
-          "requires": {
-            "ansi-styles": "^3.2.1",
-            "escape-string-regexp": "^1.0.5",
-            "supports-color": "^5.3.0"
-          }
-        },
-        "source-map": {
-          "version": "0.6.1"
-        },
-        "supports-color": {
-          "version": "5.5.0",
-          "requires": {
-            "has-flag": "^3.0.0"
-          }
-        }
+        "nanoid": "^3.3.4",
+        "picocolors": "^1.0.0",
+        "source-map-js": "^1.0.2"
       }
     },
     "postcss-value-parser": {
@@ -22635,7 +22157,9 @@
       }
     },
     "source-map-js": {
-      "version": "1.0.1"
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.0.2.tgz",
+      "integrity": "sha512-R0XvVJ9WusLiqTCEiGCmICCMplcCkIwwR11mOSD9CR5u+IXYdiseeEuXCVAjS54zqwkLcPNnmU4OeJ6tUrWhDw=="
     },
     "source-map-support": {
       "version": "0.5.20",
@@ -23166,17 +22690,6 @@
     "through": {
       "version": "2.3.8"
     },
-    "thunkify": {
-      "version": "2.1.2",
-      "dev": true
-    },
-    "thunkify-wrap": {
-      "version": "1.0.4",
-      "dev": true,
-      "requires": {
-        "enable": "1"
-      }
-    },
     "tiny-emitter": {
       "version": "2.1.0"
     },
@@ -23320,19 +22833,6 @@
     "unpipe": {
       "version": "1.0.0"
     },
-    "unyield": {
-      "version": "0.0.1",
-      "dev": true,
-      "requires": {
-        "co": "~3.1.0"
-      },
-      "dependencies": {
-        "co": {
-          "version": "3.1.0",
-          "dev": true
-        }
-      }
-    },
     "uri-js": {
       "version": "4.2.2",
       "requires": {
@@ -23558,7 +23058,6 @@
     },
     "ware": {
       "version": "1.3.0",
-      "dev": true,
       "requires": {
         "wrap-fn": "^0.1.0"
       }
@@ -23606,14 +23105,12 @@
     },
     "wrap-fn": {
       "version": "0.1.5",
-      "dev": true,
       "requires": {
         "co": "3.1.0"
       },
       "dependencies": {
         "co": {
-          "version": "3.1.0",
-          "dev": true
+          "version": "3.1.0"
         }
       }
     },
diff --git a/package.json b/package.json
index ab7c107865..13713e93e1 100644
--- a/package.json
+++ b/package.json
@@ -28,6 +28,7 @@
     ]
   },
   "dependencies": {
+    "@metalsmith/postcss": "^5.0.0",
     "acorn": "^6.4.1",
     "autoprefixer": "^9.5.1",
     "clipboard": "^2.0.4",
@@ -38,9 +39,8 @@
     "highlight.js": "^10.4.1",
     "html5shiv": "^3.7.3",
     "lunr": "^2.3.6",
-    "metalsmith-postcss": "^4.2.0",
     "modernizr": "^3.7.1",
-    "postcss": "^6.0.23",
+    "postcss": "^8.4.14",
     "sass-export": "^2.1.0",
     "serve-static": "^1.13.2",
     "slugger": "^1.0.1"