diff --git a/package.json b/package.json
index e2f7613..ef987c2 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,6 @@
     "grunt-contrib-cssmin": "^1.0.1",
     "grunt-contrib-uglify": "^1.0.1",
     "grunt-contrib-watch": "^1.0.0",
-    "grunt-sass": "^1.2.0"
+    "grunt-sass": "^2.1.0"
   }
 }
diff --git a/yarn.lock b/yarn.lock
index 5151547..19edb33 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -179,6 +179,10 @@ camelcase@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/camelcase/-/camelcase-3.0.0.tgz#32fc4b9fcdaf845fcdf7e73bb97cac2261f0ab0a"
 
+caseless@~0.11.0:
+  version "0.11.0"
+  resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.11.0.tgz#715b96ea9841593cc33067923f5ec60ebda4f7d7"
+
 caseless@~0.12.0:
   version "0.12.0"
   resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.12.0.tgz#1b681c21ff84033c826543090689420d187151dc"
@@ -283,6 +287,10 @@ commander@2.8.x:
   dependencies:
     graceful-readlink ">= 1.0.0"
 
+commander@^2.9.0:
+  version "2.15.1"
+  resolved "https://registry.yarnpkg.com/commander/-/commander-2.15.1.tgz#df46e867d0fc2aec66a34662b406a9ccafff5b0f"
+
 concat-map@0.0.1:
   version "0.0.1"
   resolved "https://registry.yarnpkg.com/concat-map/-/concat-map-0.0.1.tgz#d8a96bd77fd68df7793a73036a3ba0d5405d477b"
@@ -478,6 +486,16 @@ gaze@^1.0.0:
   dependencies:
     globule "^1.0.0"
 
+generate-function@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/generate-function/-/generate-function-2.0.0.tgz#6858fe7c0969b7d4e9093337647ac79f60dfbe74"
+
+generate-object-property@^1.1.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/generate-object-property/-/generate-object-property-1.2.0.tgz#9c0e1c40308ce804f4783618b937fa88f99d50d0"
+  dependencies:
+    is-property "^1.0.0"
+
 get-caller-file@^1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/get-caller-file/-/get-caller-file-1.0.2.tgz#f702e63127e7e231c160a80c1554acb70d5047e5"
@@ -496,6 +514,16 @@ getpass@^0.1.1:
   dependencies:
     assert-plus "^1.0.0"
 
+glob@^6.0.4:
+  version "6.0.4"
+  resolved "https://registry.yarnpkg.com/glob/-/glob-6.0.4.tgz#0f08860f6a155127b2fadd4f9ce24b1aab6e4d22"
+  dependencies:
+    inflight "^1.0.4"
+    inherits "2"
+    minimatch "2 || 3"
+    once "^1.3.0"
+    path-is-absolute "^1.0.0"
+
 glob@^7.0.0, glob@^7.0.3, glob@^7.0.6, glob@~7.1.1:
   version "7.1.1"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.1.tgz#805211df04faaf1c63a3600306cdf5ade50b2ec8"
@@ -629,12 +657,12 @@ grunt-legacy-util@~1.0.0:
     underscore.string "~3.2.3"
     which "~1.2.1"
 
-grunt-sass@^1.2.0:
-  version "1.2.1"
-  resolved "https://registry.yarnpkg.com/grunt-sass/-/grunt-sass-1.2.1.tgz#fb87b6caac46fb32d45177fd2e4b6ff7468c1919"
+grunt-sass@^2.1.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/grunt-sass/-/grunt-sass-2.1.0.tgz#b7ba1d85ef4c2d9b7d8195fe65f664ac7554efa1"
   dependencies:
     each-async "^1.0.0"
-    node-sass "^3.7.0"
+    node-sass "^4.7.2"
     object-assign "^4.0.1"
 
 grunt@^1.0.1:
@@ -669,6 +697,15 @@ har-schema@^1.0.5:
   version "1.0.5"
   resolved "https://registry.yarnpkg.com/har-schema/-/har-schema-1.0.5.tgz#d263135f43307c02c602afc8fe95970c0151369e"
 
+har-validator@~2.0.6:
+  version "2.0.6"
+  resolved "https://registry.yarnpkg.com/har-validator/-/har-validator-2.0.6.tgz#cdcbc08188265ad119b6a5a7c8ab70eecfb5d27d"
+  dependencies:
+    chalk "^1.1.1"
+    commander "^2.9.0"
+    is-my-json-valid "^2.12.4"
+    pinkie-promise "^2.0.0"
+
 har-validator@~4.2.1:
   version "4.2.1"
   resolved "https://registry.yarnpkg.com/har-validator/-/har-validator-4.2.1.tgz#33481d0f1bbff600dd203d75812a6a5fba002e2a"
@@ -758,7 +795,7 @@ inflight@^1.0.4:
     once "^1.3.0"
     wrappy "1"
 
-inherits@2, inherits@^2.0.3, inherits@~2.0.0, inherits@~2.0.1:
+inherits@2, inherits@^2.0.3, inherits@~2.0.0, inherits@~2.0.1, inherits@~2.0.3:
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/inherits/-/inherits-2.0.3.tgz#633c2c83e3da42a502f52466022480f4208261de"
 
@@ -792,6 +829,24 @@ is-fullwidth-code-point@^1.0.0:
   dependencies:
     number-is-nan "^1.0.0"
 
+is-my-ip-valid@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/is-my-ip-valid/-/is-my-ip-valid-1.0.0.tgz#7b351b8e8edd4d3995d4d066680e664d94696824"
+
+is-my-json-valid@^2.12.4:
+  version "2.17.2"
+  resolved "https://registry.yarnpkg.com/is-my-json-valid/-/is-my-json-valid-2.17.2.tgz#6b2103a288e94ef3de5cf15d29dd85fc4b78d65c"
+  dependencies:
+    generate-function "^2.0.0"
+    generate-object-property "^1.1.0"
+    is-my-ip-valid "^1.0.0"
+    jsonpointer "^4.0.0"
+    xtend "^4.0.0"
+
+is-property@^1.0.0:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/is-property/-/is-property-1.0.2.tgz#57fe1c4e48474edd65b09911f26b1cd4095dda84"
+
 is-typedarray@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/is-typedarray/-/is-typedarray-1.0.0.tgz#e479c80858df0c1b11ddda6940f96011fcda4a9a"
@@ -851,6 +906,10 @@ jsonify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/jsonify/-/jsonify-0.0.0.tgz#2c74b6ee41d93ca51b7b5aaee8f503631d252a73"
 
+jsonpointer@^4.0.0:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/jsonpointer/-/jsonpointer-4.0.1.tgz#4fd92cb34e0e9db3c89c8622ecf51f9b978c6cb9"
+
 jsprim@^1.2.2:
   version "1.4.0"
   resolved "https://registry.yarnpkg.com/jsprim/-/jsprim-1.4.0.tgz#a3b87e40298d8c380552d8cc7628a0bb95a22918"
@@ -898,6 +957,10 @@ lodash.clonedeep@^4.3.2:
   version "4.5.0"
   resolved "https://registry.yarnpkg.com/lodash.clonedeep/-/lodash.clonedeep-4.5.0.tgz#e23f3f9c4f8fbdde872529c1071857a086e5ccef"
 
+lodash.mergewith@^4.6.0:
+  version "4.6.1"
+  resolved "https://registry.yarnpkg.com/lodash.mergewith/-/lodash.mergewith-4.6.1.tgz#639057e726c3afbdb3e7d42741caa8d6e4335927"
+
 lodash@^3.10.1, lodash@~3.10.1:
   version "3.10.1"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-3.10.1.tgz#5bf45e8e49ba4189e17d482789dfd15bd140b7b6"
@@ -998,9 +1061,9 @@ ms@0.7.1:
   version "0.7.1"
   resolved "https://registry.yarnpkg.com/ms/-/ms-0.7.1.tgz#9cd13c03adbff25b65effde7ce864ee952017098"
 
-nan@^2.3.2:
-  version "2.6.2"
-  resolved "https://registry.yarnpkg.com/nan/-/nan-2.6.2.tgz#e4ff34e6c95fdfb5aecc08de6596f43605a7db45"
+nan@^2.10.0:
+  version "2.10.0"
+  resolved "https://registry.yarnpkg.com/nan/-/nan-2.10.0.tgz#96d0cd610ebd58d4b4de9cc0c6828cda99c7548f"
 
 node-gyp@^3.3.1:
   version "3.6.1"
@@ -1020,9 +1083,9 @@ node-gyp@^3.3.1:
     tar "^2.0.0"
     which "1"
 
-node-sass@^3.7.0:
-  version "3.13.1"
-  resolved "https://registry.yarnpkg.com/node-sass/-/node-sass-3.13.1.tgz#7240fbbff2396304b4223527ed3020589c004fc2"
+node-sass@^4.7.2:
+  version "4.9.0"
+  resolved "https://registry.yarnpkg.com/node-sass/-/node-sass-4.9.0.tgz#d1b8aa855d98ed684d6848db929a20771cc2ae52"
   dependencies:
     async-foreach "^0.1.3"
     chalk "^1.1.1"
@@ -1033,13 +1096,16 @@ node-sass@^3.7.0:
     in-publish "^2.0.0"
     lodash.assign "^4.2.0"
     lodash.clonedeep "^4.3.2"
+    lodash.mergewith "^4.6.0"
     meow "^3.7.0"
     mkdirp "^0.5.1"
-    nan "^2.3.2"
+    nan "^2.10.0"
     node-gyp "^3.3.1"
     npmlog "^4.0.0"
-    request "^2.61.0"
-    sass-graph "^2.1.1"
+    request "~2.79.0"
+    sass-graph "^2.2.4"
+    stdout-stream "^1.4.0"
+    "true-case-path" "^1.0.2"
 
 "nopt@2 || 3", nopt@~3.0.6:
   version "3.0.6"
@@ -1182,6 +1248,10 @@ process-nextick-args@~1.0.6:
   version "1.0.7"
   resolved "https://registry.yarnpkg.com/process-nextick-args/-/process-nextick-args-1.0.7.tgz#150e20b756590ad3f91093f25a4f2ad8bff30ba3"
 
+process-nextick-args@~2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/process-nextick-args/-/process-nextick-args-2.0.0.tgz#a37d732f4271b4ab1ad070d35508e8290788ffaa"
+
 pseudomap@^1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/pseudomap/-/pseudomap-1.0.2.tgz#f052a28da70e618917ef0a8ac34c1ae5a68286b3"
@@ -1198,6 +1268,10 @@ qs@~5.1.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/qs/-/qs-5.1.0.tgz#4d932e5c7ea411cca76a312d39a606200fd50cd9"
 
+qs@~6.3.0:
+  version "6.3.2"
+  resolved "https://registry.yarnpkg.com/qs/-/qs-6.3.2.tgz#e75bd5f6e268122a2a0e0bda630b2550c166502c"
+
 qs@~6.4.0:
   version "6.4.0"
   resolved "https://registry.yarnpkg.com/qs/-/qs-6.4.0.tgz#13e26d28ad6b0ffaa91312cd3bf708ed351e7233"
@@ -1225,6 +1299,18 @@ read-pkg@^1.0.0:
     normalize-package-data "^2.3.2"
     path-type "^1.0.0"
 
+readable-stream@^2.0.1:
+  version "2.3.6"
+  resolved "https://registry.yarnpkg.com/readable-stream/-/readable-stream-2.3.6.tgz#b11c27d88b8ff1fbe070643cf94b0c79ae1b0aaf"
+  dependencies:
+    core-util-is "~1.0.0"
+    inherits "~2.0.3"
+    isarray "~1.0.0"
+    process-nextick-args "~2.0.0"
+    safe-buffer "~5.1.1"
+    string_decoder "~1.1.1"
+    util-deprecate "~1.0.1"
+
 readable-stream@^2.0.6, readable-stream@^2.2.2:
   version "2.2.9"
   resolved "https://registry.yarnpkg.com/readable-stream/-/readable-stream-2.2.9.tgz#cf78ec6f4a6d1eb43d26488cac97f042e74b7fc8"
@@ -1254,7 +1340,7 @@ repeating@^2.0.0:
   dependencies:
     is-finite "^1.0.0"
 
-request@2, request@^2.61.0:
+request@2:
   version "2.81.0"
   resolved "https://registry.yarnpkg.com/request/-/request-2.81.0.tgz#c6928946a0e06c5f8d6f8a9333469ffda46298a0"
   dependencies:
@@ -1281,6 +1367,31 @@ request@2, request@^2.61.0:
     tunnel-agent "^0.6.0"
     uuid "^3.0.0"
 
+request@~2.79.0:
+  version "2.79.0"
+  resolved "https://registry.yarnpkg.com/request/-/request-2.79.0.tgz#4dfe5bf6be8b8cdc37fcf93e04b65577722710de"
+  dependencies:
+    aws-sign2 "~0.6.0"
+    aws4 "^1.2.1"
+    caseless "~0.11.0"
+    combined-stream "~1.0.5"
+    extend "~3.0.0"
+    forever-agent "~0.6.1"
+    form-data "~2.1.1"
+    har-validator "~2.0.6"
+    hawk "~3.1.3"
+    http-signature "~1.1.0"
+    is-typedarray "~1.0.0"
+    isstream "~0.1.2"
+    json-stringify-safe "~5.0.1"
+    mime-types "~2.1.7"
+    oauth-sign "~0.8.1"
+    qs "~6.3.0"
+    stringstream "~0.0.4"
+    tough-cookie "~2.3.0"
+    tunnel-agent "~0.4.1"
+    uuid "^3.0.0"
+
 require-directory@^2.1.1:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/require-directory/-/require-directory-2.1.1.tgz#8c64ad5fd30dab1c976e2344ffe7f792a6a6df42"
@@ -1311,18 +1422,22 @@ safe-buffer@^5.0.1:
   version "5.0.1"
   resolved "https://registry.yarnpkg.com/safe-buffer/-/safe-buffer-5.0.1.tgz#d263ca54696cd8a306b5ca6551e92de57918fbe7"
 
-sass-graph@^2.1.1:
-  version "2.2.2"
-  resolved "https://registry.yarnpkg.com/sass-graph/-/sass-graph-2.2.2.tgz#f4d6c95b546ea2a09d14176d0fc1a07ee2b48354"
+safe-buffer@~5.1.0, safe-buffer@~5.1.1:
+  version "5.1.2"
+  resolved "https://registry.yarnpkg.com/safe-buffer/-/safe-buffer-5.1.2.tgz#991ec69d296e0313747d59bdfd2b745c35f8828d"
+
+sass-graph@^2.2.4:
+  version "2.2.4"
+  resolved "https://registry.yarnpkg.com/sass-graph/-/sass-graph-2.2.4.tgz#13fbd63cd1caf0908b9fd93476ad43a51d1e0b49"
   dependencies:
     glob "^7.0.0"
     lodash "^4.0.0"
-    scss-tokenizer "^0.2.1"
-    yargs "^6.6.0"
+    scss-tokenizer "^0.2.3"
+    yargs "^7.0.0"
 
-scss-tokenizer@^0.2.1:
-  version "0.2.1"
-  resolved "https://registry.yarnpkg.com/scss-tokenizer/-/scss-tokenizer-0.2.1.tgz#07c0cc577bb7ab4d08fd900185adbf4bc844141d"
+scss-tokenizer@^0.2.3:
+  version "0.2.3"
+  resolved "https://registry.yarnpkg.com/scss-tokenizer/-/scss-tokenizer-0.2.3.tgz#8eb06db9a9723333824d3f5530641149847ce5d1"
   dependencies:
     js-base64 "^2.1.8"
     source-map "^0.4.2"
@@ -1396,6 +1511,12 @@ statuses@1:
   version "1.3.1"
   resolved "https://registry.yarnpkg.com/statuses/-/statuses-1.3.1.tgz#faf51b9eb74aaef3b3acf4ad5f61abf24cb7b93e"
 
+stdout-stream@^1.4.0:
+  version "1.4.0"
+  resolved "https://registry.yarnpkg.com/stdout-stream/-/stdout-stream-1.4.0.tgz#a2c7c8587e54d9427ea9edb3ac3f2cd522df378b"
+  dependencies:
+    readable-stream "^2.0.1"
+
 string-width@^1.0.1, string-width@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/string-width/-/string-width-1.0.2.tgz#118bdf5b8cdc51a2a7e70d211e07e2b0b9b107d3"
@@ -1410,6 +1531,12 @@ string_decoder@~1.0.0:
   dependencies:
     buffer-shims "~1.0.0"
 
+string_decoder@~1.1.1:
+  version "1.1.1"
+  resolved "https://registry.yarnpkg.com/string_decoder/-/string_decoder-1.1.1.tgz#9cf1611ba62685d7030ae9e4ba34149c3af03fc8"
+  dependencies:
+    safe-buffer "~5.1.0"
+
 stringstream@~0.0.4:
   version "0.0.5"
   resolved "https://registry.yarnpkg.com/stringstream/-/stringstream-0.0.5.tgz#4e484cd4de5a0bbbee18e46307710a8a81621878"
@@ -1483,12 +1610,22 @@ trim-newlines@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/trim-newlines/-/trim-newlines-1.0.0.tgz#5887966bb582a4503a41eb524f7d35011815a613"
 
+"true-case-path@^1.0.2":
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/true-case-path/-/true-case-path-1.0.2.tgz#7ec91130924766c7f573be3020c34f8fdfd00d62"
+  dependencies:
+    glob "^6.0.4"
+
 tunnel-agent@^0.6.0:
   version "0.6.0"
   resolved "https://registry.yarnpkg.com/tunnel-agent/-/tunnel-agent-0.6.0.tgz#27a5dea06b36b04a0a9966774b290868f0fc40fd"
   dependencies:
     safe-buffer "^5.0.1"
 
+tunnel-agent@~0.4.1:
+  version "0.4.3"
+  resolved "https://registry.yarnpkg.com/tunnel-agent/-/tunnel-agent-0.4.3.tgz#6373db76909fe570e08d73583365ed828a74eeeb"
+
 tweetnacl@^0.14.3, tweetnacl@~0.14.0:
   version "0.14.5"
   resolved "https://registry.yarnpkg.com/tweetnacl/-/tweetnacl-0.14.5.tgz#5ae68177f192d4456269d108afa93ff8743f4f64"
@@ -1599,6 +1736,10 @@ wrappy@1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/wrappy/-/wrappy-1.0.2.tgz#b5243d8f3ec1aa35f1364605bc0d1036e30ab69f"
 
+xtend@^4.0.0:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/xtend/-/xtend-4.0.1.tgz#a5c6d532be656e23db820efb943a1f04998d63af"
+
 y18n@^3.2.1:
   version "3.2.1"
   resolved "https://registry.yarnpkg.com/y18n/-/y18n-3.2.1.tgz#6d15fba884c08679c0d77e88e7759e811e07fa41"
@@ -1607,15 +1748,15 @@ yallist@^2.0.0:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/yallist/-/yallist-2.1.2.tgz#1c11f9218f076089a47dd512f93c6699a6a81d52"
 
-yargs-parser@^4.2.0:
-  version "4.2.1"
-  resolved "https://registry.yarnpkg.com/yargs-parser/-/yargs-parser-4.2.1.tgz#29cceac0dc4f03c6c87b4a9f217dd18c9f74871c"
+yargs-parser@^5.0.0:
+  version "5.0.0"
+  resolved "https://registry.yarnpkg.com/yargs-parser/-/yargs-parser-5.0.0.tgz#275ecf0d7ffe05c77e64e7c86e4cd94bf0e1228a"
   dependencies:
     camelcase "^3.0.0"
 
-yargs@^6.6.0:
-  version "6.6.0"
-  resolved "https://registry.yarnpkg.com/yargs/-/yargs-6.6.0.tgz#782ec21ef403345f830a808ca3d513af56065208"
+yargs@^7.0.0:
+  version "7.1.0"
+  resolved "https://registry.yarnpkg.com/yargs/-/yargs-7.1.0.tgz#6ba318eb16961727f5d284f8ea003e8d6154d0c8"
   dependencies:
     camelcase "^3.0.0"
     cliui "^3.2.0"
@@ -1629,7 +1770,7 @@ yargs@^6.6.0:
     string-width "^1.0.2"
     which-module "^1.0.0"
     y18n "^3.2.1"
-    yargs-parser "^4.2.0"
+    yargs-parser "^5.0.0"
 
 yargs@~3.10.0:
   version "3.10.0"