diff --git a/src/wp-admin/css/common.css b/src/wp-admin/css/common.css
index 0d843cb5bf..9da493c94c 100644
--- a/src/wp-admin/css/common.css
+++ b/src/wp-admin/css/common.css
@@ -1376,7 +1376,7 @@ div.error {
 	background: #fff;
 	border: 1px solid #ccd0d4;
 	border-left-width: 4px;
-	box-shadow: 0 1px 1px rgba(0,0,0,.04);
+	box-shadow: 0 1px 1px rgba(0, 0, 0, .04);
 	margin: 5px 15px 2px;
 	padding: 1px 12px;
 }
diff --git a/src/wp-admin/css/customize-controls.css b/src/wp-admin/css/customize-controls.css
index 491a7807e8..86d5e5881d 100644
--- a/src/wp-admin/css/customize-controls.css
+++ b/src/wp-admin/css/customize-controls.css
@@ -2354,11 +2354,12 @@ body.cheatin {
 	font-size: medium;
 	height: auto;
 	background: #fff;
+	border: 1px solid #ccd0d4;
 	margin: 50px auto 2em;
 	padding: 1em 2em;
 	max-width: 700px;
 	min-width: 0;
-	box-shadow: 0 1px 3px rgba(0, 0, 0, 0.13);
+	box-shadow: 0 1px 1px rgba(0, 0, 0, .04);
 }
 
 body.cheatin h1 {
diff --git a/src/wp-admin/css/install.css b/src/wp-admin/css/install.css
index 4c60c51437..5cba0b22ca 100644
--- a/src/wp-admin/css/install.css
+++ b/src/wp-admin/css/install.css
@@ -5,13 +5,14 @@ html {
 
 body {
 	background: #fff;
+	border: 1px solid #ccd0d4;
 	color: #444;
 	font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
 	margin: 140px auto 25px;
 	padding: 20px 20px 10px 20px;
 	max-width: 700px;
 	-webkit-font-smoothing: subpixel-antialiased;
-	box-shadow: 0 1px 3px rgba(0, 0, 0, 0.13);
+	box-shadow: 0 1px 1px rgba(0, 0, 0, .04);
 }
 
 a {
@@ -149,8 +150,6 @@ textarea {
 	line-height: 1.33333333;
 	font-size: 15px;
 	padding: 3px 5px;
-	border: 1px solid #ddd;
-	box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.07);
 }
 
 input,
diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 6e89f55c93..0ea8c9a6a7 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -3502,13 +3502,14 @@ function _default_wp_die_handler( $message, $title = '', $args = array() ) {
 		}
 		body {
 			background: #fff;
+			border: 1px solid #ccd0d4;
 			color: #444;
 			font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
 			margin: 2em auto;
 			padding: 1em 2em;
 			max-width: 700px;
-			-webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.13);
-			box-shadow: 0 1px 3px rgba(0, 0, 0, 0.13);
+			-webkit-box-shadow: 0 1px 1px rgba(0, 0, 0, .04);
+			box-shadow: 0 1px 1px rgba(0, 0, 0, .04);
 		}
 		h1 {
 			border-bottom: 1px solid #dadada;
@@ -3553,9 +3554,9 @@ function _default_wp_die_handler( $message, $title = '', $args = array() ) {
 			outline: none;
 		}
 		.button {
-			background: #f7f7f7;
-			border: 1px solid #ccc;
-			color: #555;
+			background: #f3f5f6;
+			border: 1px solid #016087;
+			color: #016087;
 			display: inline-block;
 			text-decoration: none;
 			font-size: 13px;
@@ -3572,36 +3573,35 @@ function _default_wp_die_handler( $message, $title = '', $args = array() ) {
 			-moz-box-sizing:    border-box;
 			box-sizing:         border-box;
 
-			-webkit-box-shadow: 0 1px 0 #ccc;
-			box-shadow: 0 1px 0 #ccc;
 			vertical-align: top;
 		}
 
 		.button.button-large {
-			height: 30px;
-			line-height: 2.15384615;
-			padding: 0 12px 2px;
+			line-height: 2.30769231;
+			min-height: 32px;
+			padding: 0 12px;
 		}
 
 		.button:hover,
 		.button:focus {
-			background: #fafafa;
-			border-color: #999;
-			color: #23282d;
+			background: #f1f1f1;
 		}
 
 		.button:focus {
-			border-color: #5b9dd9;
-			-webkit-box-shadow: 0 0 3px rgba(0, 115, 170, 0.8);
-			box-shadow: 0 0 3px rgba(0, 115, 170, 0.8);
-			outline: none;
+			background: #f3f5f6;
+			border-color: #007cba;
+			-webkit-box-shadow: 0 0 0 1px #007cba;
+			box-shadow: 0 0 0 1px #007cba;
+			color: #016087;
+			outline: 2px solid transparent;
+			outline-offset: 0;
 		}
 
 		.button:active {
-			background: #eee;
-			border-color: #999;
-			-webkit-box-shadow: inset 0 2px 5px -3px rgba(0, 0, 0, 0.5);
-			box-shadow: inset 0 2px 5px -3px rgba(0, 0, 0, 0.5);
+			background: #f3f5f6;
+			border-color: #7e8993;
+			-webkit-box-shadow: none;
+			box-shadow: none;
 		}
 
 		<?php