Index: src/wp-admin/css/colors/_admin.scss
===================================================================
--- src/wp-admin/css/colors/_admin.scss	(revision 45933)
+++ src/wp-admin/css/colors/_admin.scss	(working copy)
@@ -2,6 +2,9 @@
 @import 'variables';
 @import 'mixins';
 
+@function url-friendly-colour( $color ) {
+	@return '%23' + str-slice( '#{ $color }', 2, -1 );
+}
 
 body {
 	background: $body-background;
@@ -30,11 +33,11 @@
 
 /* Forms */
 
-input[type=checkbox]:checked:before {
-	color: $form-checked;
+input[type=checkbox]:checked::before {
+	content: url("data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox%3D%270%200%2020%2020%27%3E%3Cpath%20d%3D%27M14.83%204.89l1.34.94-5.81%208.38H9.02L5.78%209.67l1.34-1.25%202.57%202.4z%27%20fill%3D%27#{url-friendly-colour($form-checked)}%27%2F%3E%3C%2Fsvg%3E");
 }
 
-input[type=radio]:checked:before {
+input[type=radio]:checked::before {
 	background: $form-checked;
 }
 
Index: src/wp-admin/css/forms.css
===================================================================
--- src/wp-admin/css/forms.css	(revision 45933)
+++ src/wp-admin/css/forms.css	(working copy)
@@ -77,14 +77,14 @@
 	cursor: pointer;
 	display: inline-block;
 	line-height: 0;
-	height: 16px;
-	margin: -4px 4px 0 0;
+	height: 1rem;
+	margin: -0.25rem 0.25rem 0 0;
 	outline: 0;
 	padding: 0 !important;
 	text-align: center;
 	vertical-align: middle;
-	width: 16px;
-	min-width: 16px;
+	width: 1rem;
+	min-width: 1rem;
 	-webkit-appearance: none;
 	box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
 	transition: .05s border-color ease-in-out;
@@ -115,36 +115,35 @@
 
 input[type="radio"] {
 	border-radius: 50%;
-	margin-right: 4px;
+	margin-right: 0.25rem;
 	line-height: 0.71428571;
 }
 
-input[type="checkbox"]:checked:before,
-input[type="radio"]:checked:before {
+input[type="checkbox"]:checked::before,
+input[type="radio"]:checked::before {
 	float: left;
 	display: inline-block;
 	vertical-align: middle;
-	width: 16px;
-	font: normal 21px/1 dashicons;
+	width: 1rem;
 	speak: none;
 	-webkit-font-smoothing: antialiased;
 	-moz-osx-font-smoothing: grayscale;
 }
 
-input[type="checkbox"]:checked:before {
-	content: "\f147";
-	margin: -3px 0 0 -4px;
-	color: #1e8cbe;
+input[type="checkbox"]:checked::before {
+	/* Use the "Yes" SVG Dashicon */
+	content: url("data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox%3D%270%200%2020%2020%27%3E%3Cpath%20d%3D%27M14.83%204.89l1.34.94-5.81%208.38H9.02L5.78%209.67l1.34-1.25%202.57%202.4z%27%20fill%3D%27%231e8cbe%27%2F%3E%3C%2Fsvg%3E");
+	margin: -0.1875rem 0 0 -0.25rem;
+	height: 1.3125rem;
+	width: 1.3125rem;
 }
 
-input[type="radio"]:checked:before {
-	content: "\2022";
-	text-indent: -9999px;
-	border-radius: 50px;
-	font-size: 24px;
-	width: 6px;
-	height: 6px;
-	margin: 4px;
+input[type="radio"]:checked::before {
+	content: "";
+	border-radius: 50%;
+	width: 50%;
+	height: 50%;
+	margin: 25%;
 	line-height: 0.76190476;
 	background-color: #1e8cbe;
 }
@@ -1261,7 +1260,6 @@
 	.widefat thead td input[type="checkbox"],
 	.widefat tfoot td input[type="checkbox"] {
 		-webkit-appearance: none;
-		padding: 10px;
 	}
 
 	.widefat th input[type="checkbox"],
@@ -1274,26 +1272,27 @@
 	.widefat th input[type="checkbox"]:before,
 	.widefat thead td input[type="checkbox"]:before,
 	.widefat tfoot td input[type="checkbox"]:before {
-		font: normal 30px/1 dashicons;
-		margin: -3px -5px;
+		width: 1.875rem;
+		height: 1.875rem;
+		margin: -0.1875rem -0.3125rem;
 	}
 
 	input[type="radio"],
 	input[type="checkbox"] {
-		height: 25px;
-		width: 25px;
+		height: 1.5625rem;
+		width: 1.5625rem;
 	}
 
 	.wp-admin p input[type="checkbox"],
 	.wp-admin p input[type="radio"] {
-		margin-top: -3px;
+		margin-top: -0.1875rem;
 	}
 
 	input[type="radio"]:checked:before {
 		vertical-align: middle;
-		width: 9px;
-		height: 9px;
-		margin: 7px;
+		width: 0.5625rem;
+		height: 0.5625rem;
+		margin: 0.4375rem;
 		line-height: 0.76190476;
 	}