diff --git a/package.json b/package.json
index f0d202e..f39df16 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
   "scripts": {
     "build": "npm-run-all clean -lp build:**",
     "build:ts": "tsc -p tsconfig-build.json",
-    "build:less": "lessc --source-map styles/index.less react-mosaic-component.css",
+    "build:less": "lessc --autoprefix=defaults --source-map styles/index.less react-mosaic-component.css",
     "bundle": "rm -rf docs/ && webpack --config webpack/bundle.ts",
     "clean": "rm -rf lib/",
     "start": "webpack-dev-server --config webpack/hot.ts",
@@ -52,6 +52,7 @@
     "jsdom-global": "^3.0.2",
     "less": "^3.9.0",
     "less-loader": "^5.0.0",
+    "less-plugin-autoprefix": "^2.0.0",
     "mocha": "^6.1.4",
     "mocha-junit-reporter": "^1.23.0",
     "npm-run-all": "^4.1.5",
diff --git a/styles/blueprint-theme.less b/styles/blueprint-theme.less
index db5c7c3..5c16a00 100644
--- a/styles/blueprint-theme.less
+++ b/styles/blueprint-theme.less
@@ -163,7 +163,7 @@
 
       &.additional-controls-open {
         .mosaic-window-toolbar {
-          box-shadow: 0 1px 0 @pt-dark-elevation-shadow-0;
+          box-shadow: @pt-dark-elevation-shadow-0;
         }
       }
 
diff --git a/yarn.lock b/yarn.lock
index 41ffd08..a0e3d96 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -500,6 +500,18 @@ autoprefixer@^6.3.1:
     postcss "^5.2.16"
     postcss-value-parser "^3.2.3"
 
+autoprefixer@^8.6.3:
+  version "8.6.5"
+  resolved "https://registry.yarnpkg.com/autoprefixer/-/autoprefixer-8.6.5.tgz#343f3d193ed568b3208e00117a1b96eb691d4ee9"
+  integrity sha512-PLWJN3Xo/rycNkx+mp8iBDMTm3FeWe4VmYaZDSqL5QQB9sLsQkG5k8n+LNDFnhh9kdq2K+egL/icpctOmDHwig==
+  dependencies:
+    browserslist "^3.2.8"
+    caniuse-lite "^1.0.30000864"
+    normalize-range "^0.1.2"
+    num2fraction "^1.2.2"
+    postcss "^6.0.23"
+    postcss-value-parser "^3.2.3"
+
 aws-sign2@~0.7.0:
   version "0.7.0"
   resolved "https://registry.yarnpkg.com/aws-sign2/-/aws-sign2-0.7.0.tgz#b46e890934a9591f2d2f6f86d7e6a9f1b3fe76a8"
@@ -723,6 +735,14 @@ browserslist@^1.3.6, browserslist@^1.5.2, browserslist@^1.7.6:
     caniuse-db "^1.0.30000639"
     electron-to-chromium "^1.2.7"
 
+browserslist@^3.2.8:
+  version "3.2.8"
+  resolved "https://registry.yarnpkg.com/browserslist/-/browserslist-3.2.8.tgz#b0005361d6471f0f5952797a76fc985f1f978fc6"
+  integrity sha512-WHVocJYavUwVgVViC0ORikPHQquXwVh939TaelZ4WDqpWgTX/FsGhl/+P4qBUAGcRvtOgDgC+xftNWWp2RUTAQ==
+  dependencies:
+    caniuse-lite "^1.0.30000844"
+    electron-to-chromium "^1.3.47"
+
 buffer-indexof@^1.0.0:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/buffer-indexof/-/buffer-indexof-1.1.1.tgz#52fabcc6a606d1a00302802648ef68f639da268c"
@@ -833,6 +853,11 @@ caniuse-db@^1.0.30000529, caniuse-db@^1.0.30000634, caniuse-db@^1.0.30000639:
   resolved "https://registry.yarnpkg.com/caniuse-db/-/caniuse-db-1.0.30000976.tgz#33c6bc12934b003baaa9c1fa9de399122d26e2f9"
   integrity sha512-QvzPHBh2cYmilQAiiamun3ooHRGKFKtVwLzzx0RG7avjpj7Gii89Yzs92EKeHNqbAA2rlcFXg4GzP/tC68OGuw==
 
+caniuse-lite@^1.0.30000844, caniuse-lite@^1.0.30000864:
+  version "1.0.30000976"
+  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30000976.tgz#d30fe12662cb2a21e130d307db9907513ca830a2"
+  integrity sha512-tleNB1IwPRqZiod6nUNum63xQCMN96BUO2JTeiwuRM7p9d616EHsMBjBWJMudX39qCaPuWY8KEWzMZq7A9XQMQ==
+
 caseless@~0.12.0:
   version "0.12.0"
   resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.12.0.tgz#1b681c21ff84033c826543090689420d187151dc"
@@ -1678,7 +1703,7 @@ ee-first@1.1.1:
   resolved "https://registry.yarnpkg.com/ee-first/-/ee-first-1.1.1.tgz#590c61156b0ae2f4f0255732a158b266bc56b21d"
   integrity sha1-WQxhFWsK4vTwJVcyoViyZrxWsh0=
 
-electron-to-chromium@^1.2.7:
+electron-to-chromium@^1.2.7, electron-to-chromium@^1.3.47:
   version "1.3.170"
   resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.3.170.tgz#2dc858f8a9bb51bbfe3a429312c11f565b456e61"
   integrity sha512-vDEhHcwMogbM+WXDTh6ZktwQOqLcK7MJdCOM99UZXRI1ct3Y9OeYYJTrIHnswzv+IYwoXNj0Furh+K6UotcHVg==
@@ -3247,6 +3272,14 @@ less-loader@^5.0.0:
     loader-utils "^1.1.0"
     pify "^4.0.1"
 
+less-plugin-autoprefix@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/less-plugin-autoprefix/-/less-plugin-autoprefix-2.0.0.tgz#778e6f2fe56884381c4fc3c747b0879e944f8481"
+  integrity sha512-UktaMtHAhCVTIQxjlceo1MiiQiUZws7gi3hfcpxkCLn1CJdVdlRGCb4n1/M64hniw2DLd7YzOl7ojshs1tWYcQ==
+  dependencies:
+    autoprefixer "^8.6.3"
+    postcss "^6.0.22"
+
 less@^3.9.0:
   version "3.9.0"
   resolved "https://registry.yarnpkg.com/less/-/less-3.9.0.tgz#b7511c43f37cf57dc87dffd9883ec121289b1474"
@@ -4651,7 +4684,7 @@ postcss@^5.0.10, postcss@^5.0.11, postcss@^5.0.12, postcss@^5.0.13, postcss@^5.0
     source-map "^0.5.6"
     supports-color "^3.2.3"
 
-postcss@^6.0.1:
+postcss@^6.0.1, postcss@^6.0.22, postcss@^6.0.23:
   version "6.0.23"
   resolved "https://registry.yarnpkg.com/postcss/-/postcss-6.0.23.tgz#61c82cc328ac60e677645f979054eb98bc0e3324"
   integrity sha512-soOk1h6J3VMTZtVeVpv15/Hpdl2cBLX3CAw4TAbkpTJiNPk9YP/zWcD1ND+xEtvyuuvKzbxliTOIyvkSeSJ6ag==