use overlay styles for command pallete

src/packages/command-palette/src/command-palette-view.coffee

@@ -9,7 +9,7 @@ class CommandPaletteView extends SelectList
     @instance = new CommandPaletteView(rootView)
 
   @viewClass: ->
-    "#{super} command-palette"
+    "#{super} command-palette overlay from-top"
 
   filterKey: 'eventDescription'
 

themes/atom-dark-ui/command-palette.css

@@ -1,12 +1,3 @@
-.command-palette {
-  width: 50%;
-  margin-left: -25%;
-}
-
-.command-palette ol {
-  max-height: 300px;
-}
-
 .command-palette ol .event-description {
   float: left;
   display: inline-block;
@@ -14,10 +5,6 @@
   margin: 4px 0;
 }
 
-.command-palette li .right {
-  float: right;
-}
-
 .command-palette ol .event-name, .command-palette ol .key-binding {
   display: inline-block;
   margin: 4px 0;

themes/atom-dark-ui/select-list.css

@@ -13,6 +13,10 @@
   padding: 5px;
 }
 
+.select-list li .right {
+  float: right;
+}
+
 .select-list ol li:last-child {
   border-bottom: none;
 }