diff --git a/package.json b/package.json
index 588f993..a6a613f 100644
--- a/package.json
+++ b/package.json
@@ -56,7 +56,7 @@
         "gulp-uglify": "3.0.2",
         "gulp-zip": "4.2.0",
         "postcss-color-function": "4.1.0",
-        "postcss-custom-properties": "8.0.11",
+        "postcss-custom-properties": "9.0.2",
         "postcss-easy-import": "3.0.0",
         "pump": "3.0.0"
     },
diff --git a/yarn.lock b/yarn.lock
index 39b3564..2d035bf 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -620,7 +620,7 @@ color-name@1.1.3:
   version "1.1.3"
   resolved "https://registry.yarnpkg.com/color-name/-/color-name-1.1.3.tgz#a7d0558bd89c42f795dd42328f740831ca53bc25"
 
-color-name@^1.0.0:
+color-name@^1.0.0, color-name@^1.1.4:
   version "1.1.4"
   resolved "https://registry.yarnpkg.com/color-name/-/color-name-1.1.4.tgz#c2a09a87acbde69543de6f63fa3995c826c536a2"
 
@@ -1402,10 +1402,6 @@ flagged-respawn@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/flagged-respawn/-/flagged-respawn-1.0.1.tgz#e7de6f1279ddd9ca9aac8a5971d618606b3aab41"
 
-flatten@^1.0.2:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/flatten/-/flatten-1.0.2.tgz#dae46a9d78fbe25292258cc1e780a41d95c03782"
-
 flush-write-stream@^1.0.2:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/flush-write-stream/-/flush-write-stream-1.1.1.tgz#8dd7d873a1babc207d94ead0c2e0e44276ebf2e8"
@@ -1946,6 +1942,10 @@ invert-kv@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/invert-kv/-/invert-kv-1.0.0.tgz#104a8e4aaca6d3d8cd157a8ef8bfab2d7a3ffdb6"
 
+ip-regex@^4.1.0:
+  version "4.1.0"
+  resolved "https://registry.yarnpkg.com/ip-regex/-/ip-regex-4.1.0.tgz#5ad62f685a14edb421abebc2fff8db94df67b455"
+
 ipaddr.js@1.9.0:
   version "1.9.0"
   resolved "https://registry.yarnpkg.com/ipaddr.js/-/ipaddr.js-1.9.0.tgz#37df74e430a0e47550fe54a2defe30d8acd95f65"
@@ -2092,6 +2092,10 @@ is-number@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/is-number/-/is-number-4.0.0.tgz#0026e37f5454d73e356dfe6564699867c6a7f0ff"
 
+is-number@^7.0.0:
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/is-number/-/is-number-7.0.0.tgz#7535345b896734d5f80c4d06c50955527a14f12b"
+
 is-obj@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/is-obj/-/is-obj-1.0.1.tgz#3e4729ac1f5fde025cd7d83a896dab9f4f67db0f"
@@ -2144,6 +2148,12 @@ is-unc-path@^1.0.0:
   dependencies:
     unc-path-regex "^0.1.2"
 
+is-url-superb@^3.0.0:
+  version "3.0.0"
+  resolved "https://registry.yarnpkg.com/is-url-superb/-/is-url-superb-3.0.0.tgz#b9a1da878a1ac73659047d1e6f4ef22c209d3e25"
+  dependencies:
+    url-regex "^5.0.0"
+
 is-utf8@^0.2.0, is-utf8@^0.2.1:
   version "0.2.1"
   resolved "https://registry.yarnpkg.com/is-utf8/-/is-utf8-0.2.1.tgz#4b0da1442104d1b336340e80797e865cf39f7d72"
@@ -2992,12 +3002,12 @@ postcss-convert-values@^4.0.1:
     postcss "^7.0.0"
     postcss-value-parser "^3.0.0"
 
-postcss-custom-properties@8.0.11:
-  version "8.0.11"
-  resolved "https://registry.yarnpkg.com/postcss-custom-properties/-/postcss-custom-properties-8.0.11.tgz#2d61772d6e92f22f5e0d52602df8fae46fa30d97"
+postcss-custom-properties@9.0.2:
+  version "9.0.2"
+  resolved "https://registry.yarnpkg.com/postcss-custom-properties/-/postcss-custom-properties-9.0.2.tgz#091aefaa309826302d53ec6d780fbe1df8f40fd4"
   dependencies:
     postcss "^7.0.17"
-    postcss-values-parser "^2.0.1"
+    postcss-values-parser "^3.0.5"
 
 postcss-discard-comments@^4.0.2:
   version "4.0.2"
@@ -3252,13 +3262,15 @@ postcss-value-parser@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/postcss-value-parser/-/postcss-value-parser-4.0.0.tgz#99a983d365f7b2ad8d0f9b8c3094926eab4b936d"
 
-postcss-values-parser@^2.0.1:
-  version "2.0.1"
-  resolved "https://registry.yarnpkg.com/postcss-values-parser/-/postcss-values-parser-2.0.1.tgz#da8b472d901da1e205b47bdc98637b9e9e550e5f"
+postcss-values-parser@^3.0.5:
+  version "3.0.5"
+  resolved "https://registry.yarnpkg.com/postcss-values-parser/-/postcss-values-parser-3.0.5.tgz#9f83849fb89eaac74c2d5bf75e8e9715508a8c8d"
   dependencies:
-    flatten "^1.0.2"
-    indexes-of "^1.0.1"
-    uniq "^1.0.1"
+    color-name "^1.1.4"
+    is-number "^7.0.0"
+    is-url-superb "^3.0.0"
+    postcss "^7.0.5"
+    url-regex "^5.0.0"
 
 postcss@^6.0.1, postcss@^6.0.11, postcss@^6.0.23:
   version "6.0.23"
@@ -4046,6 +4058,10 @@ tiny-lr@^1.1.1:
     object-assign "^4.1.0"
     qs "^6.4.0"
 
+tlds@^1.203.0:
+  version "1.203.1"
+  resolved "https://registry.yarnpkg.com/tlds/-/tlds-1.203.1.tgz#4dc9b02f53de3315bc98b80665e13de3edfc1dfc"
+
 to-absolute-glob@^2.0.0:
   version "2.0.2"
   resolved "https://registry.yarnpkg.com/to-absolute-glob/-/to-absolute-glob-2.0.2.tgz#1865f43d9e74b0822db9f145b78cff7d0f7c849b"
@@ -4202,6 +4218,13 @@ urix@^0.1.0:
   version "0.1.0"
   resolved "https://registry.yarnpkg.com/urix/-/urix-0.1.0.tgz#da937f7a62e21fec1fd18d49b35c2935067a6c72"
 
+url-regex@^5.0.0:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/url-regex/-/url-regex-5.0.0.tgz#8f5456ab83d898d18b2f91753a702649b873273a"
+  dependencies:
+    ip-regex "^4.1.0"
+    tlds "^1.203.0"
+
 use@^3.1.0:
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/use/-/use-3.1.1.tgz#d50c8cac79a19fbc20f2911f56eb973f4e10070f"