use postcss via hugo pipes instead of cli

yarn.lock

@@ -1447,16 +1447,7 @@ class-utils@^0.3.5:
     isobject "^3.0.0"
     static-extend "^0.1.1"
 
-clean-css-cli@^4.3.0:
-  version "4.3.0"
-  resolved "https://registry.yarnpkg.com/clean-css-cli/-/clean-css-cli-4.3.0.tgz#8502aa86d1879e5b111af51b3c2abb799e0684ce"
-  integrity sha512-8GHZfr+mG3zB/Lgqrr27qHBFsPSn0fyEI3f2rIZpxPxUbn2J6A8xyyeBRVTW8duDuXigN0s80vsXiXJOEFIO5Q==
-  dependencies:
-    clean-css "^4.2.1"
-    commander "2.x"
-    glob "7.x"
-
-clean-css@^4.2.1:
+clean-css@^4.2.1, clean-css@^4.x:
   version "4.2.1"
   resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.2.1.tgz#2d411ef76b8569b6d0c84068dabe85b0aa5e5c17"
   integrity sha512-4ZxI6dy4lrY6FHzfiy1aEOXgu4LIsW2MhwG0VBKdcoGoH/XLFgaHSdLTGr4O8Be6A8r3MOphEiI8Gc1n0ecf3g==
@@ -1681,7 +1672,7 @@ colors@^1.1.2:
   resolved "https://registry.yarnpkg.com/colors/-/colors-1.4.0.tgz#c50491479d4c1bdaed2c9ced32cf7c7dc2360f78"
   integrity sha512-a+UqTh4kgZg/SlGvfbzDHpgRu7AAQOmmqRHJnxhRZICKFUT91brVhNNt58CMWU9PsBbv3PDCZUHbVxuDiH2mtA==
 
-commander@2.x, commander@^2.11.0, commander@^2.19.0, commander@^2.3.0, commander@~2.20.3:
+commander@^2.11.0, commander@^2.19.0, commander@^2.3.0, commander@~2.20.3:
   version "2.20.3"
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.20.3.tgz#fd485e84c03eb4881c20722ba48035e8531aeb33"
   integrity sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==
@@ -3370,7 +3361,7 @@ glob-to-regexp@^0.3.0:
   resolved "https://registry.yarnpkg.com/glob-to-regexp/-/glob-to-regexp-0.3.0.tgz#8c5a1494d2066c570cc3bfe4496175acc4d502ab"
   integrity sha1-jFoUlNIGbFcMw7/kSWF1rMTVAqs=
 
-glob@7.x, glob@^7.1.3, glob@^7.1.4, glob@^7.1.6, glob@~7.1.2:
+glob@^7.1.3, glob@^7.1.4, glob@^7.1.6, glob@~7.1.2:
   version "7.1.6"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.6.tgz#141f33b81a7c2492e125594307480c46679278a6"
   integrity sha512-LwaxwyZ72Lk7vZINtNNrywX0ZuLyStrdDtabefZKAY5ZGJhVtgdznluResxNmPitE0SAO+O26sWTHeKSI2wMBA==
@@ -6542,6 +6533,14 @@ posix-character-classes@^0.1.0:
   resolved "https://registry.yarnpkg.com/posix-character-classes/-/posix-character-classes-0.1.1.tgz#01eac0fe3b5af71a2a6c02feabb8c1fef7e00eab"
   integrity sha1-AerA/jta9xoqbAL+q7jB/vfgDqs=
 
+postcss-clean@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/postcss-clean/-/postcss-clean-1.1.0.tgz#c2d61d5d8caf19a585adba16897726c2674c4207"
+  integrity sha512-83g3GqMbCM5NL6MlbbPLJ/m2NrUepBF44MoDk4Gt04QGXeXKh9+ilQa0DzLnYnvqYHQCw83nckuEzBFr2muwbg==
+  dependencies:
+    clean-css "^4.x"
+    postcss "^6.x"
+
 postcss-cli@^7.1.0:
   version "7.1.0"
   resolved "https://registry.yarnpkg.com/postcss-cli/-/postcss-cli-7.1.0.tgz#769b07b8865aaa3e98c7c63a3d256b4f51e3e237"
@@ -6684,7 +6683,25 @@ postcss-values-parser@^1.5.0:
     indexes-of "^1.0.1"
     uniq "^1.0.1"
 
-postcss@^7.0.0, postcss@^7.0.14, postcss@^7.0.17, postcss@^7.0.2, postcss@^7.0.21, postcss@^7.0.23, postcss@^7.0.7:
+postcss@^6.x:
+  version "6.0.23"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-6.0.23.tgz#61c82cc328ac60e677645f979054eb98bc0e3324"
+  integrity sha512-soOk1h6J3VMTZtVeVpv15/Hpdl2cBLX3CAw4TAbkpTJiNPk9YP/zWcD1ND+xEtvyuuvKzbxliTOIyvkSeSJ6ag==
+  dependencies:
+    chalk "^2.4.1"
+    source-map "^0.6.1"
+    supports-color "^5.4.0"
+
+postcss@^7.0.0, postcss@^7.0.14, postcss@^7.0.2, postcss@^7.0.21, postcss@^7.0.23, postcss@^7.0.7:
+  version "7.0.24"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-7.0.24.tgz#972c3c5be431b32e40caefe6c81b5a19117704c2"
+  integrity sha512-Xl0XvdNWg+CblAXzNvbSOUvgJXwSjmbAKORqyw9V2AlHrm1js2gFw9y3jibBAhpKZi8b5JzJCVh/FyzPsTtgTA==
+  dependencies:
+    chalk "^2.4.2"
+    source-map "^0.6.1"
+    supports-color "^6.1.0"
+
+postcss@^7.0.17:
   version "7.0.26"
   resolved "https://registry.yarnpkg.com/postcss/-/postcss-7.0.26.tgz#5ed615cfcab35ba9bbb82414a4fa88ea10429587"
   integrity sha512-IY4oRjpXWYshuTDFxMVkJDtWIk2LhsTlu8bZnbEJA4+bYT16Lvpo8Qv6EvDumhYRgzjZl489pmsY3qVgJQ08nA==