Index: wp-content/themes/twentythirteen/style.css
===================================================================
--- wp-content/themes/twentythirteen/style.css	(revision 23495)
+++ wp-content/themes/twentythirteen/style.css	(working copy)
@@ -544,6 +544,36 @@
 	display: table;
 }
 
+/* Box sizing */
+.site-header hgroup,
+.site-header .searchform .field,
+.site-main .widget-area,
+.site-footer .widget-area,
+.site-footer .widget,
+.sidebar .entry-header,
+.sidebar .entry-content,
+.sidebar .entry-summary,
+.sidebar .entry-meta,
+.sidebar .archive-meta,
+.sidebar .page-content,
+.sidebar .comments-title,
+.sidebar .comment-list,
+.sidebar .no-comments,
+.sidebar #reply-title,
+.sidebar .comment-navigation,
+.sidebar #respond #commentform,
+.sidebar .paging-navigation .nav-links,
+.sidebar .post-navigation .nav-links,
+.author.sidebar .author-info,
+.format-status .entry-content,
+.format-status .entry-meta,
+.widget .searchform .field,
+#commentform textarea {
+	-webkit-box-sizing: border-box;
+	-moz-box-sizing:    border-box;
+	box-sizing:         border-box;
+}
+
 /* Assistive text */
 .assistive-text {
 	position: absolute !important;
@@ -809,9 +839,6 @@
 }
 
 .site-header hgroup {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	margin: 0 auto;
 	max-width: 1040px;
 	min-height: 230px;
@@ -953,9 +980,6 @@
 	border: none;
 	cursor: pointer;
 	height: 37px;
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	-webkit-transition: width 400ms ease, background 400ms ease;
 	-o-transition:      width 400ms ease, background 400ms ease;
 	transition:         width 400ms ease, background 400ms ease;
@@ -1046,9 +1070,6 @@
 .sidebar .entry-content,
 .sidebar .entry-summary,
 .sidebar .entry-meta {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	max-width: 1040px;
 	padding: 0 376px 0 60px;
 }
@@ -1671,9 +1692,6 @@
 
 .format-status .entry-content,
 .format-status .entry-meta {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	padding-left: 35px;
 	position: relative;
 }
@@ -1937,9 +1955,6 @@
 }
 
 .sidebar .paging-navigation .nav-links {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	max-width: 1040px;
 	padding: 0 376px 0 60px;
 }
@@ -1991,9 +2006,6 @@
 }
 
 .sidebar .post-navigation .nav-links {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	padding: 0 376px 0 60px;
 }
 
@@ -2016,9 +2028,6 @@
 }
 
 .author.sidebar .author-info {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	max-width: 1040px;
 	padding: 30px 376px 10px 60px;
 }
@@ -2087,9 +2096,6 @@
 }
 
 .sidebar .archive-meta {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	padding-right: 316px;
 }
 
@@ -2119,9 +2125,6 @@
 }
 
 .sidebar .page-content {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	margin: 0 auto;
 	max-width: 1040px;
 	padding: 40px 376px 40px 60px;
@@ -2189,9 +2192,6 @@
 .sidebar #reply-title,
 .sidebar .comment-navigation,
 .sidebar #respond #commentform {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	max-width: 1040px;
 	padding-left: 60px;
 	padding-right: 376px;
@@ -2366,9 +2366,6 @@
 
 #commentform textarea {
 	width: 100%;
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 }
 
 .form-allowed-tags,
@@ -2406,9 +2403,6 @@
 }
 
 .sidebar .no-comments {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	padding-left: 60px;
 	padding-right: 376px;
 }
@@ -2420,9 +2414,6 @@
  */
 
 .site-main .widget-area {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	float: right;
 	width: 300px;
 }
@@ -2480,9 +2471,6 @@
 }
 
 .widget .searchform .field {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	width: 100%;
 }
 
@@ -2558,9 +2546,6 @@
 }
 
 .site-footer .widget-area {
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	margin: 0 auto;
 	padding: 20px 0;
 	max-width: 1040px;
@@ -2574,9 +2559,6 @@
 
 .site-footer .widget {
 	background: transparent;
-	-webkit-box-sizing: border-box;
-	-moz-box-sizing:    border-box;
-	box-sizing:         border-box;
 	color: #fff;
 	float: left;
 	margin-right: 20px;