diff --git a/docs/4.0/utilities/flex.md b/docs/4.0/utilities/flex.md
index 1d28fab6dd..c9aa5d2997 100644
--- a/docs/4.0/utilities/flex.md
+++ b/docs/4.0/utilities/flex.md
@@ -215,20 +215,24 @@ Responsive variations also exist for `align-self`.
 
 ## Auto margins
 
-Flexbox can do some pretty awesome things when you mix flex alignments with auto margins.
+Flexbox can do some pretty awesome things when you mix flex alignments with auto margins. Shown below is are three examples of controlling flex items via auto margins: default (no auto margin), pushing two items to the right (`.mr-auto`), and pushing two items to the left (`.ml-auto`).
 
-### With justify-content
-
-Easily move all flex items to one side, but keep another on the opposite end by mixing `justify-content` with `margin-right: auto` or `margin-left: auto`.
+**Unfortunately, IE10 and IE11 do not properly support auto margins on flex items whose parent has a non-default `justify-content` value.** [See this StackOverflow answer](https://stackoverflow.com/a/37535548) for more details.
 
 {% example html %}
-<div class="d-flex justify-content-end bd-highlight mb-3">
+<div class="d-flex bd-highlight mb-3">
+  <div class="p-2 bd-highlight">Flex item</div>
+  <div class="p-2 bd-highlight">Flex item</div>
+  <div class="p-2 bd-highlight">Flex item</div>
+</div>
+
+<div class="d-flex bd-highlight mb-3">
   <div class="mr-auto p-2 bd-highlight">Flex item</div>
   <div class="p-2 bd-highlight">Flex item</div>
   <div class="p-2 bd-highlight">Flex item</div>
 </div>
 
-<div class="d-flex justify-content-start bd-highlight">
+<div class="d-flex bd-highlight mb-3">
   <div class="p-2 bd-highlight">Flex item</div>
   <div class="p-2 bd-highlight">Flex item</div>
   <div class="ml-auto p-2 bd-highlight">Flex item</div>
@@ -237,7 +241,7 @@ Easily move all flex items to one side, but keep another on the opposite end by
 
 ### With align-items
 
-Similarly, move one flex item to the top or bottom of a container by mixing `align-items`, `flex-direction: column`, and `margin-top: auto` or `margin-bottom: auto`.
+Vertically move one flex item to the top or bottom of a container by mixing `align-items`, `flex-direction: column`, and `margin-top: auto` or `margin-bottom: auto`.
 
 {% example html %}
 <div class="d-flex align-items-start flex-column bd-highlight mb-3" style="height: 200px;">
diff --git a/package.json b/package.json
index c6e9c4b03a..2e533f8731 100644
--- a/package.json
+++ b/package.json
@@ -36,12 +36,12 @@
     "js-lint": "eslint js/ && eslint --config js/tests/.eslintrc.json --env node build/",
     "js-lint-docs": "eslint --config js/tests/.eslintrc.json assets/js/ docs/ sw.js",
     "js-compile": "npm-run-all --parallel js-compile-*",
-    "js-compile-standalone": "cross-env ROLLUP=true rollup --environment BUNDLE:false --config build/rollup.config.js",
-    "js-compile-bundle": "cross-env ROLLUP=true rollup --environment BUNDLE:true --config build/rollup.config.js",
+    "js-compile-standalone": "cross-env ROLLUP=true rollup --environment BUNDLE:false --config build/rollup.config.js --sourcemap",
+    "js-compile-bundle": "cross-env ROLLUP=true rollup --environment BUNDLE:true --config build/rollup.config.js --sourcemap",
     "js-compile-plugins": "cross-env PLUGINS=true babel js/src/ --out-dir js/dist/ --source-maps",
     "js-minify": "npm-run-all --parallel js-minify-*",
-    "js-minify-standalone": "uglifyjs --compress typeofs=false --mangle --comments \"/^!/\" --output dist/js/bootstrap.min.js dist/js/bootstrap.js",
-    "js-minify-bundle": "uglifyjs --compress typeofs=false --mangle --comments \"/^!/\" --output dist/js/bootstrap.bundle.min.js dist/js/bootstrap.bundle.js",
+    "js-minify-standalone": "uglifyjs --compress typeofs=false --mangle --comments \"/^!/\" --source-map \"content=dist/js/bootstrap.js.map,includeSources,url=bootstrap.min.js.map\" --output dist/js/bootstrap.min.js dist/js/bootstrap.js",
+    "js-minify-bundle": "uglifyjs --compress typeofs=false --mangle --comments \"/^!/\" --source-map \"content=dist/js/bootstrap.bundle.js.map,includeSources,url=bootstrap.bundle.min.js.map\" --output dist/js/bootstrap.bundle.min.js dist/js/bootstrap.bundle.js",
     "js-minify-docs": "uglifyjs --mangle --comments \"/^!/\" --output assets/js/docs.min.js assets/js/vendor/anchor.min.js assets/js/vendor/clipboard.min.js assets/js/vendor/holder.min.js assets/js/src/application.js assets/js/src/pwa.js",
     "js-test": "phantomjs ./node_modules/qunit-phantomjs-runner/runner.js js/tests/index.html 60",
     "js-test-cloud": "ruby -r webrick -e \"s = WEBrick::HTTPServer.new(:Port => 3000, :DocumentRoot => Dir.pwd, :Logger => WEBrick::Log.new('/dev/null'), :AccessLog => []); trap('INT') { s.shutdown }; s.start\" & node build/saucelabs-unit-test.js",
@@ -125,6 +125,7 @@
     "build",
     "js/.eslintrc.json",
     "js/**/*.js",
+    "js/**/*.js.map",
     "scss/**/*.scss"
   ],
   "browserslist": [
diff --git a/scss/_variables.scss b/scss/_variables.scss
index 3d78f0b8ae..af0846806e 100644
--- a/scss/_variables.scss
+++ b/scss/_variables.scss
@@ -62,16 +62,25 @@ $colors: map-merge((
   "gray-dark":  $gray-800
 ), $colors);
 
+$primary:       $blue !default;
+$secondary:     $gray-600 !default;
+$success:       $green !default;
+$info:          $cyan !default;
+$warning:       $yellow !default;
+$danger:        $red !default;
+$light:         $gray-100 !default;
+$dark:          $gray-800 !default;
+
 $theme-colors: () !default;
 $theme-colors: map-merge((
-  "primary":    $blue,
-  "secondary":  $gray-600,
-  "success":    $green,
-  "info":       $cyan,
-  "warning":    $yellow,
-  "danger":     $red,
-  "light":      $gray-100,
-  "dark":       $gray-800
+  "primary":    $primary,
+  "secondary":  $secondary,
+  "success":    $success,
+  "info":       $info,
+  "warning":    $warning,
+  "danger":     $danger,
+  "light":      $light,
+  "dark":       $dark
 ), $theme-colors);
 // stylelint-enable