diff --git a/spec/app/window-spec.coffee b/spec/app/window-spec.coffee
index 0ae136754..dac3771aa 100644
--- a/spec/app/window-spec.coffee
+++ b/spec/app/window-spec.coffee
@@ -64,19 +64,19 @@ describe "Window", ->
 
   describe "requireStylesheet(path)", ->
     it "synchronously loads the stylesheet at the given path and installs a style tag for it in the head", ->
-      $('head style[id*="atom.css"]').remove()
+      $('head style[id*="atom.less"]').remove()
       lengthBefore = $('head style').length
-      requireStylesheet('atom.css')
+      requireStylesheet('atom.less')
       expect($('head style').length).toBe lengthBefore + 1
 
-      styleElt = $('head style[id*="atom.css"]')
+      styleElt = $('head style[id*="atom.less"]')
 
-      fullPath = require.resolve('atom.css')
+      fullPath = require.resolve('atom.less')
       expect(styleElt.attr('id')).toBe fullPath
-      expect(styleElt.text()).toBe fs.read(fullPath)
+      expect(styleElt.text()).toBe parseLessFile(fullPath)
 
       # doesn't append twice
-      requireStylesheet('atom.css')
+      requireStylesheet('atom.less')
       expect($('head style').length).toBe lengthBefore + 1
 
     it  "synchronously loads and parses less files at the given path and installs a style tag for it in the head", ->
@@ -89,10 +89,7 @@ describe "Window", ->
 
       fullPath = require.resolve('markdown.less')
       expect(styleElt.attr('id')).toBe fullPath
-
-      (new less.Parser).parse __read(fullPath), (e, tree) ->
-        throw new Error(e.message, file, e.line) if e
-        expect(styleElt.text()).toBe tree.toCSS()
+      expect(styleElt.text()).toBe parseLessFile(fullPath)
 
       # doesn't append twice
       requireStylesheet('markdown.less')
diff --git a/src/app/window.coffee b/src/app/window.coffee
index 3cab24751..4a548b5bd 100644
--- a/src/app/window.coffee
+++ b/src/app/window.coffee
@@ -25,7 +25,7 @@ window.setUpEnvironment = ->
   keymap.bindDefaultKeys()
 
   requireStylesheet 'reset.less'
-  requireStylesheet 'atom.css'
+  requireStylesheet 'atom.less'
   requireStylesheet 'tabs.css'
   requireStylesheet 'tree-view.css'
   requireStylesheet 'status-bar.css'
diff --git a/static/atom.css b/static/atom.css
deleted file mode 100644
index 6cfb79269..000000000
--- a/static/atom.css
+++ /dev/null
@@ -1,81 +0,0 @@
-html, body {
-  width: 100%;
-  height: 100%;
-  overflow: hidden;
-}
-
-#root-view {
-  height: 100%;
-  overflow: hidden;
-  position: relative;
-}
-
-#root-view #horizontal {
-  display: -webkit-flex;
-  height: 100%;
-}
-
-#root-view #vertical {
-  display: -webkit-flex;
-  -webkit-flex: 1;
-  -webkit-flex-flow: column;
-}
-
-#panes {
-  position: relative;
-  -webkit-flex: 1;
-}
-
-#panes .column {
-  position: absolute;
-  top: 0;
-  bottom: 0;
-  left: 0;
-  right: 0;
-  overflow-y: hidden;
-}
-
-#panes .row {
-  position: absolute;
-  top: 0;
-  bottom: 0;
-  left: 0;
-  right: 0;
-  overflow-x: hidden;
-}
-
-#panes .pane {
-  position: absolute;
-  display: -webkit-flex;
-  -webkit-flex-flow: column;
-  top: 0;
-  bottom: 0;
-  left: 0;
-  right: 0;
-  box-sizing: border-box;
-}
-
-#panes .pane .item-views {
-  -webkit-flex: 1;
-  display: -webkit-flex;
-  -webkit-flex-flow: column;
-}
-
-@font-face {
-  font-family: 'Octicons Regular';
-  src: url("octicons-regular-webfont.woff") format("woff");
-  font-weight: normal;
-  font-style: normal;
-}
-
-.is-loading {
-  background-image: url(images/spinner.svg);
-  background-repeat: no-repeat;
-  width: 14px;
-  height: 14px;
-  opacity: 0.5;
-  background-size: contain;
-  position: relative;
-  display: inline-block;
-  padding-left: 19px;
-}
diff --git a/static/atom.less b/static/atom.less
new file mode 100644
index 000000000..c02f90d90
--- /dev/null
+++ b/static/atom.less
@@ -0,0 +1,75 @@
+html, body {
+  width: 100%;
+  height: 100%;
+  overflow: hidden;
+}
+
+#root-view {
+  height: 100%;
+  overflow: hidden;
+  position: relative;
+
+  #horizontal {
+    display: -webkit-flex;
+    height: 100%;
+  }
+
+  #vertical {
+    display: -webkit-flex;
+    -webkit-flex: 1;
+    -webkit-flex-flow: column;
+  }
+
+  #panes {
+    position: relative;
+    -webkit-flex: 1;
+
+    .column {
+      position: absolute;
+      top: 0;
+      bottom: 0;
+      left: 0;
+      right: 0;
+      overflow-y: hidden;
+    }
+
+    .row {
+      position: absolute;
+      top: 0;
+      bottom: 0;
+      left: 0;
+      right: 0;
+      overflow-x: hidden;
+    }
+
+    .pane {
+      position: absolute;
+      display: -webkit-flex;
+      -webkit-flex-flow: column;
+      top: 0;
+      bottom: 0;
+      left: 0;
+      right: 0;
+      box-sizing: border-box;
+    }
+  }
+}
+
+@font-face {
+  font-family: 'Octicons Regular';
+  src: url("octicons-regular-webfont.woff") format("woff");
+  font-weight: normal;
+  font-style: normal;
+}
+
+.is-loading {
+  background-image: url(images/spinner.svg);
+  background-repeat: no-repeat;
+  width: 14px;
+  height: 14px;
+  opacity: 0.5;
+  background-size: contain;
+  position: relative;
+  display: inline-block;
+  padding-left: 19px;
+}