Use postcss-drop-empty-css-vars to remove empty CSS variables
diff --git a/build/postcss.config.js b/build/postcss.config.js
index 7f8186d..d25ed86 100644
--- a/build/postcss.config.js
+++ b/build/postcss.config.js
@@ -10,6 +10,7 @@
   return {
     map: context.file.dirname.includes('examples') ? false : mapConfig,
     plugins: {
+      "postcss-drop-empty-css-vars": {},
       autoprefixer: {
         cascade: false
       },
diff --git a/package-lock.json b/package-lock.json
index 73e447f..788169d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -56,6 +56,7 @@
         "npm-run-all": "^4.1.5",
         "postcss": "^8.4.14",
         "postcss-cli": "^10.0.0",
+        "postcss-drop-empty-css-vars": "^0.0.0",
         "rollup": "^2.76.0",
         "rollup-plugin-istanbul": "^3.0.0",
         "rtlcss": "^3.5.0",
@@ -7962,6 +7963,18 @@
         "node": ">=12"
       }
     },
+    "node_modules/postcss-drop-empty-css-vars": {
+      "version": "0.0.0",
+      "resolved": "https://registry.npmjs.org/postcss-drop-empty-css-vars/-/postcss-drop-empty-css-vars-0.0.0.tgz",
+      "integrity": "sha512-qJhXM6CIA0GE5FQjIO4697xpHQt9mK+EiCC8p7zv44mOvyj6uNb8GnPZhr+ZETYngfWFMOTXZqShChJHGOoyEw==",
+      "dev": true,
+      "engines": {
+        "node": ">=12.0.0"
+      },
+      "peerDependencies": {
+        "postcss": "^8.3.0"
+      }
+    },
     "node_modules/postcss-load-config": {
       "version": "4.0.1",
       "resolved": "https://registry.npmjs.org/postcss-load-config/-/postcss-load-config-4.0.1.tgz",
@@ -16307,6 +16320,13 @@
         }
       }
     },
+    "postcss-drop-empty-css-vars": {
+      "version": "0.0.0",
+      "resolved": "https://registry.npmjs.org/postcss-drop-empty-css-vars/-/postcss-drop-empty-css-vars-0.0.0.tgz",
+      "integrity": "sha512-qJhXM6CIA0GE5FQjIO4697xpHQt9mK+EiCC8p7zv44mOvyj6uNb8GnPZhr+ZETYngfWFMOTXZqShChJHGOoyEw==",
+      "dev": true,
+      "requires": {}
+    },
     "postcss-load-config": {
       "version": "4.0.1",
       "resolved": "https://registry.npmjs.org/postcss-load-config/-/postcss-load-config-4.0.1.tgz",
diff --git a/package.json b/package.json
index 4d09740..124439e 100644
--- a/package.json
+++ b/package.json
@@ -141,6 +141,7 @@
     "npm-run-all": "^4.1.5",
     "postcss": "^8.4.14",
     "postcss-cli": "^10.0.0",
+    "postcss-drop-empty-css-vars": "^0.0.0",
     "rollup": "^2.76.0",
     "rollup-plugin-istanbul": "^3.0.0",
     "rtlcss": "^3.5.0",