--- a/browser/themes/linux/places/places.css
+++ b/browser/themes/linux/places/places.css
@@ -6,17 +6,17 @@
 
 #history-panel,
 #bookmarksPanel {
   -moz-appearance: none;
   background-color: transparent;
 }
 
 #sidebar-search-container {
-  padding: 4px;
+  padding: 8px;
 }
 
 #search-box {
   margin: 0;
 }
 
 #viewButton {
   -moz-appearance: none;

--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -725,21 +725,21 @@ html|span.ac-emphasize-text-url {
 
 /* ----- SIDEBAR ELEMENTS ----- */
 
 %include ../shared/sidebar.inc.css
 
 #sidebar-box {
   -moz-appearance: -moz-mac-source-list;
   -moz-font-smoothing-background-color: -moz-mac-source-list;
+  /* Default font size is 11px on mac, so this is 12px */
+  font-size: 1.0909rem;
 }
 
 #sidebar-header {
-  /* system font size is a bit smaller in mac, so need more ems. */
-  font-size: 1.4545em;
   border-bottom: 1px solid hsla(240, 5%, 5%, .1);
   background-color: transparent;
 }
 
 .sidebar-splitter {
   border-color: hsla(240, 5%, 5%, .1);
 }
 

--- a/browser/themes/osx/places/places.css
+++ b/browser/themes/osx/places/places.css
@@ -51,16 +51,22 @@
   color: #fff;
   font-weight: bold;
 }
 
 #sidebar-search-label {
   display: none;
 }
 
+#sidebar-search-container {
+  /* Native searchbar styling already adds 4px margin on Mac, so
+   * adding 4px padding results in 8px of total whitespace. */
+  padding: 4px;
+}
+
 .sidebar-placesTreechildren::-moz-tree-twisty {
   -moz-appearance: none;
   padding: 0 2px;
   list-style-image: url("chrome://global/skin/tree/arrow-disclosure.svg#arrow-disclosure-collapsed");
 }
 
 .sidebar-placesTreechildren::-moz-tree-twisty(closed, selected) {
   list-style-image: url("chrome://global/skin/tree/arrow-disclosure.svg#arrow-disclosure-collapsed-inverted");

--- a/browser/themes/windows/places/places.css
+++ b/browser/themes/windows/places/places.css
@@ -5,17 +5,17 @@
 /* Sidebars */
 
 #history-panel,
 #bookmarksPanel {
   background-color: transparent;
 }
 
 #sidebar-search-container {
-  padding: 4px;
+  padding: 8px;
 }
 
 .sidebar-placesTree {
   -moz-appearance: none;
   background-color: transparent;
   color: inherit;
   border: 0;
   margin: 0;