diff --git a/package-lock.json b/package-lock.json
index 0be462b..ce80e1d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,10 +16,10 @@
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-        "fast-json-stable-stringify": "2.0.0",
-        "json-schema-traverse": "0.4.1",
-        "uri-js": "4.2.2"
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       "requires": {
-        "delegates": "1.0.0",
-        "readable-stream": "2.3.6"
+        "delegates": "^1.0.0",
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       "dev": true,
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-        "safer-buffer": "2.1.2"
+        "safer-buffer": "~2.1.0"
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@@ -113,7 +113,7 @@
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       "dev": true,
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-        "tweetnacl": "0.14.5"
+        "tweetnacl": "^0.14.3"
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@@ -122,7 +122,7 @@
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+        "inherits": "~2.0.0"
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       "dev": true,
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+        "balanced-match": "^1.0.0",
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@@ -153,8 +153,8 @@
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-        "map-obj": "1.0.1"
+        "camelcase": "^2.0.0",
+        "map-obj": "^1.0.0"
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@@ -169,11 +169,11 @@
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-        "has-ansi": "2.0.0",
-        "strip-ansi": "3.0.1",
-        "supports-color": "2.0.0"
+        "ansi-styles": "^2.2.1",
+        "escape-string-regexp": "^1.0.2",
+        "has-ansi": "^2.0.0",
+        "strip-ansi": "^3.0.0",
+        "supports-color": "^2.0.0"
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@@ -182,9 +182,9 @@
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-        "strip-ansi": "3.0.1",
-        "wrap-ansi": "2.1.0"
+        "string-width": "^1.0.1",
+        "strip-ansi": "^3.0.1",
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       "dev": true,
       "requires": {
-        "delayed-stream": "1.0.0"
+        "delayed-stream": "~1.0.0"
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@@ -226,8 +226,8 @@
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-        "which": "1.3.1"
+        "lru-cache": "^4.0.1",
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@@ -236,7 +236,7 @@
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+        "array-find-index": "^1.0.1"
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@@ -245,7 +245,7 @@
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+        "assert-plus": "^1.0.0"
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@@ -272,8 +272,8 @@
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       "dev": true,
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-        "jsbn": "0.1.1",
-        "safer-buffer": "2.1.2"
+        "jsbn": "~0.1.0",
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+        "is-arrayish": "^0.2.1"
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@@ -321,8 +321,8 @@
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-        "path-exists": "2.1.0",
-        "pinkie-promise": "2.0.1"
+        "path-exists": "^2.0.0",
+        "pinkie-promise": "^2.0.0"
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-        "asynckit": "0.4.0",
-        "combined-stream": "1.0.7",
-        "mime-types": "2.1.21"
+        "asynckit": "^0.4.0",
+        "combined-stream": "^1.0.6",
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@@ -354,10 +354,10 @@
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-        "inherits": "2.0.3",
-        "mkdirp": "0.5.1",
-        "rimraf": "2.6.2"
+        "graceful-fs": "^4.1.2",
+        "inherits": "~2.0.0",
+        "mkdirp": ">=0.5 0",
+        "rimraf": "2"
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@@ -366,14 +366,14 @@
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-        "has-unicode": "2.0.1",
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-        "signal-exit": "3.0.2",
-        "string-width": "1.0.2",
-        "strip-ansi": "3.0.1",
-        "wide-align": "1.1.3"
+        "aproba": "^1.0.3",
+        "console-control-strings": "^1.0.0",
+        "has-unicode": "^2.0.0",
+        "object-assign": "^4.1.0",
+        "signal-exit": "^3.0.0",
+        "string-width": "^1.0.1",
+        "strip-ansi": "^3.0.1",
+        "wide-align": "^1.1.0"
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@@ -382,7 +382,7 @@
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-        "globule": "1.2.1"
+        "globule": "^1.0.0"
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@@ -403,7 +403,7 @@
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+        "assert-plus": "^1.0.0"
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-        "inflight": "1.0.6",
-        "inherits": "2.0.3",
-        "minimatch": "3.0.4",
-        "once": "1.4.0",
-        "path-is-absolute": "1.0.1"
+        "fs.realpath": "^1.0.0",
+        "inflight": "^1.0.4",
+        "inherits": "2",
+        "minimatch": "^3.0.4",
+        "once": "^1.3.0",
+        "path-is-absolute": "^1.0.0"
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       "dev": true,
       "requires": {
-        "glob": "7.1.3",
-        "lodash": "4.17.11",
-        "minimatch": "3.0.4"
+        "glob": "~7.1.1",
+        "lodash": "~4.17.10",
+        "minimatch": "~3.0.2"
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@@ -449,8 +449,8 @@
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       "dev": true,
       "requires": {
-        "ajv": "6.6.1",
-        "har-schema": "2.0.0"
+        "ajv": "^6.5.5",
+        "har-schema": "^2.0.0"
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@@ -459,7 +459,7 @@
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       "dev": true,
       "requires": {
-        "ansi-regex": "2.1.1"
+        "ansi-regex": "^2.0.0"
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@@ -480,9 +480,9 @@
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       "dev": true,
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-        "assert-plus": "1.0.0",
-        "jsprim": "1.4.1",
-        "sshpk": "1.15.2"
+        "assert-plus": "^1.0.0",
+        "jsprim": "^1.2.2",
+        "sshpk": "^1.7.0"
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@@ -497,7 +497,7 @@
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       "dev": true,
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-        "repeating": "2.0.1"
+        "repeating": "^2.0.0"
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@@ -506,8 +506,8 @@
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       "dev": true,
       "requires": {
-        "once": "1.4.0",
-        "wrappy": "1.0.2"
+        "once": "^1.3.0",
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@@ -534,7 +534,7 @@
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       "dev": true,
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-        "builtin-modules": "1.1.1"
+        "builtin-modules": "^1.0.0"
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@@ -543,7 +543,7 @@
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       "dev": true,
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@@ -552,7 +552,7 @@
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       "dev": true,
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+        "number-is-nan": "^1.0.0"
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       "dev": true,
       "requires": {
-        "invert-kv": "1.0.0"
+        "invert-kv": "^1.0.0"
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@@ -642,11 +642,11 @@
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-        "pify": "2.3.0",
-        "pinkie-promise": "2.0.1",
-        "strip-bom": "2.0.0"
+        "graceful-fs": "^4.1.2",
+        "parse-json": "^2.2.0",
+        "pify": "^2.0.0",
+        "pinkie-promise": "^2.0.0",
+        "strip-bom": "^2.0.0"
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@@ -679,8 +679,8 @@
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       "dev": true,
       "requires": {
-        "currently-unhandled": "0.4.1",
-        "signal-exit": "3.0.2"
+        "currently-unhandled": "^0.4.1",
+        "signal-exit": "^3.0.0"
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@@ -689,8 +689,8 @@
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-        "pseudomap": "1.0.2",
-        "yallist": "2.1.2"
+        "pseudomap": "^1.0.2",
+        "yallist": "^2.1.2"
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@@ -705,16 +705,16 @@
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-        "loud-rejection": "1.6.0",
-        "map-obj": "1.0.1",
-        "minimist": "1.2.0",
-        "normalize-package-data": "2.4.0",
-        "object-assign": "4.1.1",
-        "read-pkg-up": "1.0.1",
-        "redent": "1.0.0",
-        "trim-newlines": "1.0.0"
+        "camelcase-keys": "^2.0.0",
+        "decamelize": "^1.1.2",
+        "loud-rejection": "^1.0.0",
+        "map-obj": "^1.0.1",
+        "minimist": "^1.1.3",
+        "normalize-package-data": "^2.3.4",
+        "object-assign": "^4.0.1",
+        "read-pkg-up": "^1.0.1",
+        "redent": "^1.0.0",
+        "trim-newlines": "^1.0.0"
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@@ -729,7 +729,7 @@
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       "dev": true,
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-        "mime-db": "1.37.0"
+        "mime-db": "~1.37.0"
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@@ -738,7 +738,7 @@
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       "requires": {
-        "brace-expansion": "1.1.11"
+        "brace-expansion": "^1.1.7"
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@@ -776,18 +776,18 @@
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-        "glob": "7.1.3",
-        "graceful-fs": "4.1.15",
-        "mkdirp": "0.5.1",
-        "nopt": "3.0.6",
-        "npmlog": "4.1.2",
-        "osenv": "0.1.5",
-        "request": "2.88.0",
-        "rimraf": "2.6.2",
-        "semver": "5.3.0",
-        "tar": "2.2.1",
-        "which": "1.3.1"
+        "fstream": "^1.0.0",
+        "glob": "^7.0.3",
+        "graceful-fs": "^4.1.2",
+        "mkdirp": "^0.5.0",
+        "nopt": "2 || 3",
+        "npmlog": "0 || 1 || 2 || 3 || 4",
+        "osenv": "0",
+        "request": "^2.87.0",
+        "rimraf": "2",
+        "semver": "~5.3.0",
+        "tar": "^2.0.0",
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@@ -804,25 +804,25 @@
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-        "chalk": "1.1.3",
-        "cross-spawn": "3.0.1",
-        "gaze": "1.1.3",
-        "get-stdin": "4.0.1",
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-        "lodash.assign": "4.2.0",
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-        "lodash.mergewith": "4.6.1",
-        "meow": "3.7.0",
-        "mkdirp": "0.5.1",
-        "nan": "2.11.1",
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-        "npmlog": "4.1.2",
-        "request": "2.88.0",
-        "sass-graph": "2.2.4",
-        "stdout-stream": "1.4.1",
-        "true-case-path": "1.0.3"
+        "async-foreach": "^0.1.3",
+        "chalk": "^1.1.1",
+        "cross-spawn": "^3.0.0",
+        "gaze": "^1.0.0",
+        "get-stdin": "^4.0.1",
+        "glob": "^7.0.3",
+        "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": "^2.10.0",
+        "node-gyp": "^3.8.0",
+        "npmlog": "^4.0.0",
+        "request": "^2.88.0",
+        "sass-graph": "^2.2.4",
+        "stdout-stream": "^1.4.0",
+        "true-case-path": "^1.0.2"
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@@ -831,7 +831,7 @@
       "integrity": "sha1-xkZdvwirzU2zWTF/eaxopkayj/k=",
       "dev": true,
       "requires": {
-        "abbrev": "1.1.1"
+        "abbrev": "1"
       }
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@@ -840,10 +840,10 @@
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       "dev": true,
       "requires": {
-        "hosted-git-info": "2.7.1",
-        "is-builtin-module": "1.0.0",
-        "semver": "5.6.0",
-        "validate-npm-package-license": "3.0.4"
+        "hosted-git-info": "^2.1.4",
+        "is-builtin-module": "^1.0.0",
+        "semver": "2 || 3 || 4 || 5",
+        "validate-npm-package-license": "^3.0.1"
       }
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     "npmlog": {
@@ -852,10 +852,10 @@
       "integrity": "sha512-2uUqazuKlTaSI/dC8AzicUck7+IrEaOnN/e0jd3Xtt1KcGpwx30v50mL7oPyr/h9bL3E4aZccVwpwP+5W9Vjkg==",
       "dev": true,
       "requires": {
-        "are-we-there-yet": "1.1.5",
-        "console-control-strings": "1.1.0",
-        "gauge": "2.7.4",
-        "set-blocking": "2.0.0"
+        "are-we-there-yet": "~1.1.2",
+        "console-control-strings": "~1.1.0",
+        "gauge": "~2.7.3",
+        "set-blocking": "~2.0.0"
       }
     },
     "number-is-nan": {
@@ -882,7 +882,7 @@
       "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
       "dev": true,
       "requires": {
-        "wrappy": "1.0.2"
+        "wrappy": "1"
       }
     },
     "os-homedir": {
@@ -897,7 +897,7 @@
       "integrity": "sha1-IPnxeuKe00XoveWDsT0gCYA8FNk=",
       "dev": true,
       "requires": {
-        "lcid": "1.0.0"
+        "lcid": "^1.0.0"
       }
     },
     "os-tmpdir": {
@@ -912,8 +912,8 @@
       "integrity": "sha512-0CWcCECdMVc2Rw3U5w9ZjqX6ga6ubk1xDVKxtBQPK7wis/0F2r9T6k4ydGYhecl7YUBxBVxhL5oisPsNxAPe2g==",
       "dev": true,
       "requires": {
-        "os-homedir": "1.0.2",
-        "os-tmpdir": "1.0.2"
+        "os-homedir": "^1.0.0",
+        "os-tmpdir": "^1.0.0"
       }
     },
     "parse-json": {
@@ -922,7 +922,7 @@
       "integrity": "sha1-9ID0BDTvgHQfhGkJn43qGPVaTck=",
       "dev": true,
       "requires": {
-        "error-ex": "1.3.2"
+        "error-ex": "^1.2.0"
       }
     },
     "path-exists": {
@@ -931,7 +931,7 @@
       "integrity": "sha1-D+tsZPD8UY2adU3V77YscCJ2H0s=",
       "dev": true,
       "requires": {
-        "pinkie-promise": "2.0.1"
+        "pinkie-promise": "^2.0.0"
       }
     },
     "path-is-absolute": {
@@ -946,9 +946,9 @@
       "integrity": "sha1-WcRPfuSR2nBNpBXaWkBwuk+P5EE=",
       "dev": true,
       "requires": {
-        "graceful-fs": "4.1.15",
-        "pify": "2.3.0",
-        "pinkie-promise": "2.0.1"
+        "graceful-fs": "^4.1.2",
+        "pify": "^2.0.0",
+        "pinkie-promise": "^2.0.0"
       }
     },
     "performance-now": {
@@ -975,7 +975,7 @@
       "integrity": "sha1-ITXW36ejWMBprJsXh3YogihFD/o=",
       "dev": true,
       "requires": {
-        "pinkie": "2.0.4"
+        "pinkie": "^2.0.0"
       }
     },
     "process-nextick-args": {
@@ -1014,9 +1014,9 @@
       "integrity": "sha1-9f+qXs0pyzHAR0vKfXVra7KePyg=",
       "dev": true,
       "requires": {
-        "load-json-file": "1.1.0",
-        "normalize-package-data": "2.4.0",
-        "path-type": "1.1.0"
+        "load-json-file": "^1.0.0",
+        "normalize-package-data": "^2.3.2",
+        "path-type": "^1.0.0"
       }
     },
     "read-pkg-up": {
@@ -1025,8 +1025,8 @@
       "integrity": "sha1-nWPBMnbAZZGNV/ACpX9AobZD+wI=",
       "dev": true,
       "requires": {
-        "find-up": "1.1.2",
-        "read-pkg": "1.1.0"
+        "find-up": "^1.0.0",
+        "read-pkg": "^1.0.0"
       }
     },
     "readable-stream": {
@@ -1035,13 +1035,13 @@
       "integrity": "sha512-tQtKA9WIAhBF3+VLAseyMqZeBjW0AHJoxOtYqSUZNJxauErmLbVm2FW1y+J/YA9dUrAC39ITejlZWhVIwawkKw==",
       "dev": true,
       "requires": {
-        "core-util-is": "1.0.2",
-        "inherits": "2.0.3",
-        "isarray": "1.0.0",
-        "process-nextick-args": "2.0.0",
-        "safe-buffer": "5.1.2",
-        "string_decoder": "1.1.1",
-        "util-deprecate": "1.0.2"
+        "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"
       }
     },
     "redent": {
@@ -1050,8 +1050,8 @@
       "integrity": "sha1-z5Fqsf1fHxbfsggi3W7H9zDCr94=",
       "dev": true,
       "requires": {
-        "indent-string": "2.1.0",
-        "strip-indent": "1.0.1"
+        "indent-string": "^2.1.0",
+        "strip-indent": "^1.0.1"
       }
     },
     "repeating": {
@@ -1060,7 +1060,7 @@
       "integrity": "sha1-UhTFOpJtNVJwdSf7q0FdvAjQbdo=",
       "dev": true,
       "requires": {
-        "is-finite": "1.0.2"
+        "is-finite": "^1.0.0"
       }
     },
     "request": {
@@ -1069,26 +1069,26 @@
       "integrity": "sha512-NAqBSrijGLZdM0WZNsInLJpkJokL72XYjUpnB0iwsRgxh7dB6COrHnTBNwN0E+lHDAJzu7kLAkDeY08z2/A0hg==",
       "dev": true,
       "requires": {
-        "aws-sign2": "0.7.0",
-        "aws4": "1.8.0",
-        "caseless": "0.12.0",
-        "combined-stream": "1.0.7",
-        "extend": "3.0.2",
-        "forever-agent": "0.6.1",
-        "form-data": "2.3.3",
-        "har-validator": "5.1.3",
-        "http-signature": "1.2.0",
-        "is-typedarray": "1.0.0",
-        "isstream": "0.1.2",
-        "json-stringify-safe": "5.0.1",
-        "mime-types": "2.1.21",
-        "oauth-sign": "0.9.0",
-        "performance-now": "2.1.0",
-        "qs": "6.5.2",
-        "safe-buffer": "5.1.2",
-        "tough-cookie": "2.4.3",
-        "tunnel-agent": "0.6.0",
-        "uuid": "3.3.2"
+        "aws-sign2": "~0.7.0",
+        "aws4": "^1.8.0",
+        "caseless": "~0.12.0",
+        "combined-stream": "~1.0.6",
+        "extend": "~3.0.2",
+        "forever-agent": "~0.6.1",
+        "form-data": "~2.3.2",
+        "har-validator": "~5.1.0",
+        "http-signature": "~1.2.0",
+        "is-typedarray": "~1.0.0",
+        "isstream": "~0.1.2",
+        "json-stringify-safe": "~5.0.1",
+        "mime-types": "~2.1.19",
+        "oauth-sign": "~0.9.0",
+        "performance-now": "^2.1.0",
+        "qs": "~6.5.2",
+        "safe-buffer": "^5.1.2",
+        "tough-cookie": "~2.4.3",
+        "tunnel-agent": "^0.6.0",
+        "uuid": "^3.3.2"
       }
     },
     "require-directory": {
@@ -1109,7 +1109,7 @@
       "integrity": "sha512-lreewLK/BlghmxtfH36YYVg1i8IAce4TI7oao75I1g245+6BctqTVQiBP3YUJ9C6DQOXJmkYR9X9fCLtCOJc5w==",
       "dev": true,
       "requires": {
-        "glob": "7.1.3"
+        "glob": "^7.0.5"
       }
     },
     "safe-buffer": {
@@ -1130,10 +1130,10 @@
       "integrity": "sha1-E/vWPNHK8JCLn9k0dq1DpR0eC0k=",
       "dev": true,
       "requires": {
-        "glob": "7.1.3",
-        "lodash": "4.17.11",
-        "scss-tokenizer": "0.2.3",
-        "yargs": "7.1.0"
+        "glob": "^7.0.0",
+        "lodash": "^4.0.0",
+        "scss-tokenizer": "^0.2.3",
+        "yargs": "^7.0.0"
       }
     },
     "scss-tokenizer": {
@@ -1142,8 +1142,8 @@
       "integrity": "sha1-jrBtualyMzOCTT9VMGQRSYR85dE=",
       "dev": true,
       "requires": {
-        "js-base64": "2.4.9",
-        "source-map": "0.4.4"
+        "js-base64": "^2.1.8",
+        "source-map": "^0.4.2"
       }
     },
     "semver": {
@@ -1170,7 +1170,7 @@
       "integrity": "sha1-66T12pwNyZneaAMti092FzZSA2s=",
       "dev": true,
       "requires": {
-        "amdefine": "1.0.1"
+        "amdefine": ">=0.0.4"
       }
     },
     "spdx-correct": {
@@ -1179,8 +1179,8 @@
       "integrity": "sha512-lr2EZCctC2BNR7j7WzJ2FpDznxky1sjfxvvYEyzxNyb6lZXHODmEoJeFu4JupYlkfha1KZpJyoqiJ7pgA1qq8Q==",
       "dev": true,
       "requires": {
-        "spdx-expression-parse": "3.0.0",
-        "spdx-license-ids": "3.0.2"
+        "spdx-expression-parse": "^3.0.0",
+        "spdx-license-ids": "^3.0.0"
       }
     },
     "spdx-exceptions": {
@@ -1195,8 +1195,8 @@
       "integrity": "sha512-Yg6D3XpRD4kkOmTpdgbUiEJFKghJH03fiC1OPll5h/0sO6neh2jqRDVHOQ4o/LMea0tgCkbMgea5ip/e+MkWyg==",
       "dev": true,
       "requires": {
-        "spdx-exceptions": "2.2.0",
-        "spdx-license-ids": "3.0.2"
+        "spdx-exceptions": "^2.1.0",
+        "spdx-license-ids": "^3.0.0"
       }
     },
     "spdx-license-ids": {
@@ -1211,15 +1211,15 @@
       "integrity": "sha512-Ra/OXQtuh0/enyl4ETZAfTaeksa6BXks5ZcjpSUNrjBr0DvrJKX+1fsKDPpT9TBXgHAFsa4510aNVgI8g/+SzA==",
       "dev": true,
       "requires": {
-        "asn1": "0.2.4",
-        "assert-plus": "1.0.0",
-        "bcrypt-pbkdf": "1.0.2",
-        "dashdash": "1.14.1",
-        "ecc-jsbn": "0.1.2",
-        "getpass": "0.1.7",
-        "jsbn": "0.1.1",
-        "safer-buffer": "2.1.2",
-        "tweetnacl": "0.14.5"
+        "asn1": "~0.2.3",
+        "assert-plus": "^1.0.0",
+        "bcrypt-pbkdf": "^1.0.0",
+        "dashdash": "^1.12.0",
+        "ecc-jsbn": "~0.1.1",
+        "getpass": "^0.1.1",
+        "jsbn": "~0.1.0",
+        "safer-buffer": "^2.0.2",
+        "tweetnacl": "~0.14.0"
       }
     },
     "stdout-stream": {
@@ -1228,7 +1228,7 @@
       "integrity": "sha512-j4emi03KXqJWcIeF8eIXkjMFN1Cmb8gUlDYGeBALLPo5qdyTfA9bOtl8m33lRoC+vFMkP3gl0WsDr6+gzxbbTA==",
       "dev": true,
       "requires": {
-        "readable-stream": "2.3.6"
+        "readable-stream": "^2.0.1"
       }
     },
     "string-width": {
@@ -1237,9 +1237,9 @@
       "integrity": "sha1-EYvfW4zcUaKn5w0hHgfisLmxB9M=",
       "dev": true,
       "requires": {
-        "code-point-at": "1.1.0",
-        "is-fullwidth-code-point": "1.0.0",
-        "strip-ansi": "3.0.1"
+        "code-point-at": "^1.0.0",
+        "is-fullwidth-code-point": "^1.0.0",
+        "strip-ansi": "^3.0.0"
       }
     },
     "string_decoder": {
@@ -1248,7 +1248,7 @@
       "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
       "dev": true,
       "requires": {
-        "safe-buffer": "5.1.2"
+        "safe-buffer": "~5.1.0"
       }
     },
     "strip-ansi": {
@@ -1257,7 +1257,7 @@
       "integrity": "sha1-ajhfuIU9lS1f8F0Oiq+UJ43GPc8=",
       "dev": true,
       "requires": {
-        "ansi-regex": "2.1.1"
+        "ansi-regex": "^2.0.0"
       }
     },
     "strip-bom": {
@@ -1266,7 +1266,7 @@
       "integrity": "sha1-YhmoVhZSBJHzV4i9vxRHqZx+aw4=",
       "dev": true,
       "requires": {
-        "is-utf8": "0.2.1"
+        "is-utf8": "^0.2.0"
       }
     },
     "strip-indent": {
@@ -1275,7 +1275,7 @@
       "integrity": "sha1-DHlipq3vp7vUrDZkYKY4VSrhoKI=",
       "dev": true,
       "requires": {
-        "get-stdin": "4.0.1"
+        "get-stdin": "^4.0.1"
       }
     },
     "supports-color": {
@@ -1290,9 +1290,9 @@
       "integrity": "sha1-jk0qJWwOIYXGsYrWlK7JaLg8sdE=",
       "dev": true,
       "requires": {
-        "block-stream": "0.0.9",
-        "fstream": "1.0.11",
-        "inherits": "2.0.3"
+        "block-stream": "*",
+        "fstream": "^1.0.2",
+        "inherits": "2"
       }
     },
     "tough-cookie": {
@@ -1301,8 +1301,8 @@
       "integrity": "sha512-Q5srk/4vDM54WJsJio3XNn6K2sCG+CQ8G5Wz6bZhRZoAe/+TxjWB/GlFAnYEbkYVlON9FMk/fE3h2RLpPXo4lQ==",
       "dev": true,
       "requires": {
-        "psl": "1.1.29",
-        "punycode": "1.4.1"
+        "psl": "^1.1.24",
+        "punycode": "^1.4.1"
       },
       "dependencies": {
         "punycode": {
@@ -1325,7 +1325,7 @@
       "integrity": "sha512-m6s2OdQe5wgpFMC+pAJ+q9djG82O2jcHPOI6RNg1yy9rCYR+WD6Nbpl32fDpfC56nirdRy+opFa/Vk7HYhqaew==",
       "dev": true,
       "requires": {
-        "glob": "7.1.3"
+        "glob": "^7.1.2"
       }
     },
     "tunnel-agent": {
@@ -1334,7 +1334,7 @@
       "integrity": "sha1-J6XeoGs2sEoKmWZ3SykIaPD8QP0=",
       "dev": true,
       "requires": {
-        "safe-buffer": "5.1.2"
+        "safe-buffer": "^5.0.1"
       }
     },
     "tweetnacl": {
@@ -1349,7 +1349,7 @@
       "integrity": "sha512-KY9Frmirql91X2Qgjry0Wd4Y+YTdrdZheS8TFwvkbLWf/G5KNJDCh6pKL5OZctEW4+0Baa5idK2ZQuELRwPznQ==",
       "dev": true,
       "requires": {
-        "punycode": "2.1.1"
+        "punycode": "^2.1.0"
       }
     },
     "util-deprecate": {
@@ -1370,8 +1370,8 @@
       "integrity": "sha512-DpKm2Ui/xN7/HQKCtpZxoRWBhZ9Z0kqtygG8XCgNQ8ZlDnxuQmWhj566j8fN4Cu3/JmbhsDo7fcAJq4s9h27Ew==",
       "dev": true,
       "requires": {
-        "spdx-correct": "3.1.0",
-        "spdx-expression-parse": "3.0.0"
+        "spdx-correct": "^3.0.0",
+        "spdx-expression-parse": "^3.0.0"
       }
     },
     "verror": {
@@ -1380,9 +1380,9 @@
       "integrity": "sha1-OhBcoXBTr1XW4nDB+CiGguGNpAA=",
       "dev": true,
       "requires": {
-        "assert-plus": "1.0.0",
+        "assert-plus": "^1.0.0",
         "core-util-is": "1.0.2",
-        "extsprintf": "1.3.0"
+        "extsprintf": "^1.2.0"
       }
     },
     "which": {
@@ -1391,7 +1391,7 @@
       "integrity": "sha512-HxJdYWq1MTIQbJ3nw0cqssHoTNU267KlrDuGZ1WYlxDStUtKUhOaJmh112/TZmHxxUfuJqPXSOm7tDyas0OSIQ==",
       "dev": true,
       "requires": {
-        "isexe": "2.0.0"
+        "isexe": "^2.0.0"
       }
     },
     "which-module": {
@@ -1406,7 +1406,7 @@
       "integrity": "sha512-QGkOQc8XL6Bt5PwnsExKBPuMKBxnGxWWW3fU55Xt4feHozMUhdUMaBCk290qpm/wG5u/RSKzwdAC4i51YigihA==",
       "dev": true,
       "requires": {
-        "string-width": "1.0.2"
+        "string-width": "^1.0.2 || 2"
       }
     },
     "wrap-ansi": {
@@ -1415,8 +1415,8 @@
       "integrity": "sha1-2Pw9KE3QV5T+hJc8rs3Rz4JP3YU=",
       "dev": true,
       "requires": {
-        "string-width": "1.0.2",
-        "strip-ansi": "3.0.1"
+        "string-width": "^1.0.1",
+        "strip-ansi": "^3.0.1"
       }
     },
     "wrappy": {
@@ -1443,19 +1443,19 @@
       "integrity": "sha1-a6MY6xaWFyf10oT46gA+jWFU0Mg=",
       "dev": true,
       "requires": {
-        "camelcase": "3.0.0",
-        "cliui": "3.2.0",
-        "decamelize": "1.2.0",
-        "get-caller-file": "1.0.3",
-        "os-locale": "1.4.0",
-        "read-pkg-up": "1.0.1",
-        "require-directory": "2.1.1",
-        "require-main-filename": "1.0.1",
-        "set-blocking": "2.0.0",
-        "string-width": "1.0.2",
-        "which-module": "1.0.0",
-        "y18n": "3.2.1",
-        "yargs-parser": "5.0.0"
+        "camelcase": "^3.0.0",
+        "cliui": "^3.2.0",
+        "decamelize": "^1.1.1",
+        "get-caller-file": "^1.0.1",
+        "os-locale": "^1.4.0",
+        "read-pkg-up": "^1.0.1",
+        "require-directory": "^2.1.1",
+        "require-main-filename": "^1.0.1",
+        "set-blocking": "^2.0.0",
+        "string-width": "^1.0.2",
+        "which-module": "^1.0.0",
+        "y18n": "^3.2.1",
+        "yargs-parser": "^5.0.0"
       },
       "dependencies": {
         "camelcase": {
@@ -1472,7 +1472,7 @@
       "integrity": "sha1-J17PDX/+Bcd+ZOfIbkzZS/DhIoo=",
       "dev": true,
       "requires": {
-        "camelcase": "3.0.0"
+        "camelcase": "^3.0.0"
       },
       "dependencies": {
         "camelcase": {
diff --git a/src/packages/_middle.scss b/src/packages/_middle.scss
index 3d3890d..93e187b 100644
--- a/src/packages/_middle.scss
+++ b/src/packages/_middle.scss
@@ -8,3 +8,16 @@
   display: inline-flex;
   align-items: center;
 }
+
+@mixin pseudo-vertical-middle {
+  $sel: &;
+
+  @at-root {
+    #{$sel}::after {
+      content: "";
+      display: inline-block;
+      height: 100%;
+      vertical-align: middle;
+    }
+  }
+}
diff --git a/test/packages/middle.scss b/test/packages/middle.scss
new file mode 100644
index 0000000..a1dd975
--- /dev/null
+++ b/test/packages/middle.scss
@@ -0,0 +1,16 @@
+@import "../../src/packages/middle";
+
+.container {
+  position: fixed;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  @include pseudo-vertical-middle();
+
+  .demo1 {
+    color: red;
+
+    @include pseudo-vertical-middle();
+  }
+}