diff --git a/package-lock.json b/package-lock.json
index c9fe528..b0aff04 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -33,7 +33,7 @@
         "mermaid": "^9.2.1",
         "plyr": "^3.7.2",
         "popper.js": "^1.16.1",
-        "postcss": "^8.4.21",
+        "postcss": "^8.4.31",
         "postcss-cli": "^8.3.1"
       }
     },
@@ -2786,10 +2786,16 @@
       "dev": true
     },
     "node_modules/nanoid": {
-      "version": "3.3.4",
-      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.4.tgz",
-      "integrity": "sha512-MqBkQh/OHTS2egovRtLk45wEyNXwF+cokD+1YPf9u5VfJiRdAiRwB2froX5Co9Rh20xs4siNPm8naNotSD6RBw==",
+      "version": "3.3.6",
+      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.6.tgz",
+      "integrity": "sha512-BGcqMMJuToF7i1rt+2PWSNVnWIkGCU78jBG3RxO/bZlnZPK2Cmi2QaffxGO/2RvWi9sL+FAiRiXMgsyxQ1DIDA==",
       "dev": true,
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/ai"
+        }
+      ],
       "bin": {
         "nanoid": "bin/nanoid.cjs"
       },
@@ -3048,9 +3054,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.4.21",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.21.tgz",
-      "integrity": "sha512-tP7u/Sn/dVxK2NnruI4H9BG+x+Wxz6oeZ1cJ8P6G/PZY0IKk4k/63TDsQf2kQq3+qoJeLm2kIBUNlZe3zgb4Zg==",
+      "version": "8.4.31",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.31.tgz",
+      "integrity": "sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==",
       "dev": true,
       "funding": [
         {
@@ -3060,10 +3066,14 @@
         {
           "type": "tidelift",
           "url": "https://tidelift.com/funding/github/npm/postcss"
+        },
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/ai"
         }
       ],
       "dependencies": {
-        "nanoid": "^3.3.4",
+        "nanoid": "^3.3.6",
         "picocolors": "^1.0.0",
         "source-map-js": "^1.0.2"
       },
@@ -5860,9 +5870,9 @@
       "dev": true
     },
     "nanoid": {
-      "version": "3.3.4",
-      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.4.tgz",
-      "integrity": "sha512-MqBkQh/OHTS2egovRtLk45wEyNXwF+cokD+1YPf9u5VfJiRdAiRwB2froX5Co9Rh20xs4siNPm8naNotSD6RBw==",
+      "version": "3.3.6",
+      "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.6.tgz",
+      "integrity": "sha512-BGcqMMJuToF7i1rt+2PWSNVnWIkGCU78jBG3RxO/bZlnZPK2Cmi2QaffxGO/2RvWi9sL+FAiRiXMgsyxQ1DIDA==",
       "dev": true
     },
     "natural-compare": {
@@ -6048,12 +6058,12 @@
       "dev": true
     },
     "postcss": {
-      "version": "8.4.21",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.21.tgz",
-      "integrity": "sha512-tP7u/Sn/dVxK2NnruI4H9BG+x+Wxz6oeZ1cJ8P6G/PZY0IKk4k/63TDsQf2kQq3+qoJeLm2kIBUNlZe3zgb4Zg==",
+      "version": "8.4.31",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.31.tgz",
+      "integrity": "sha512-PS08Iboia9mts/2ygV3eLpY5ghnUcfLV/EXTOW1E2qYxJKGGBUtNjN76FYHnMs36RmARn41bC0AZmn+rR0OVpQ==",
       "dev": true,
       "requires": {
-        "nanoid": "^3.3.4",
+        "nanoid": "^3.3.6",
         "picocolors": "^1.0.0",
         "source-map-js": "^1.0.2"
       }
diff --git a/package.json b/package.json
index 7f39a0f..e3478f5 100644
--- a/package.json
+++ b/package.json
@@ -61,7 +61,7 @@
     "mermaid": "^9.2.1",
     "plyr": "^3.7.2",
     "popper.js": "^1.16.1",
-    "postcss": "^8.4.21",
+    "postcss": "^8.4.31",
     "postcss-cli": "^8.3.1"
   },
   "homepage": "https://github.com/hugo-toha/toha#readme",