diff --git a/package-lock.json b/package-lock.json
index 9632177..eadf58a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -841,12 +841,20 @@
       }
     },
     "clean-css": {
-      "version": "4.1.9",
-      "resolved": "https://registry.npmjs.org/clean-css/-/clean-css-4.1.9.tgz",
-      "integrity": "sha1-Nc7ornaHpJuYA09w3gDE7dOCYwE=",
+      "version": "4.2.1",
+      "resolved": "https://registry.npmjs.org/clean-css/-/clean-css-4.2.1.tgz",
+      "integrity": "sha512-4ZxI6dy4lrY6FHzfiy1aEOXgu4LIsW2MhwG0VBKdcoGoH/XLFgaHSdLTGr4O8Be6A8r3MOphEiI8Gc1n0ecf3g==",
       "dev": true,
       "requires": {
-        "source-map": "0.5.x"
+        "source-map": "~0.6.0"
+      },
+      "dependencies": {
+        "source-map": {
+          "version": "0.6.1",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
+          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
+          "dev": true
+        }
       }
     },
     "cliui": {
@@ -2554,6 +2562,23 @@
         "uglify-js": "3.3.x"
       },
       "dependencies": {
+        "clean-css": {
+          "version": "4.1.11",
+          "resolved": "https://registry.npmjs.org/clean-css/-/clean-css-4.1.11.tgz",
+          "integrity": "sha1-Ls3xRaujj1R0DybO/Q/z4D4SXWo=",
+          "dev": true,
+          "requires": {
+            "source-map": "0.5.x"
+          },
+          "dependencies": {
+            "source-map": {
+              "version": "0.5.7",
+              "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.5.7.tgz",
+              "integrity": "sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=",
+              "dev": true
+            }
+          }
+        },
         "source-map": {
           "version": "0.6.1",
           "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",