diff --git a/src/wp-admin/css/colors/_admin.scss b/src/wp-admin/css/colors/_admin.scss
index 553037e3d30d1..97904e7e9e352 100644
--- a/src/wp-admin/css/colors/_admin.scss
+++ b/src/wp-admin/css/colors/_admin.scss
@@ -3,6 +3,7 @@
 @forward 'variables' show $scheme-name, $base-color, $body-background, $button-color, $custom-welcome-panel, $dashboard-accent-1, $dashboard-accent-2, $dashboard-icon-background, $form-checked, $highlight-color, $icon-color, $link, $link-focus, $low-contrast-theme, $menu-bubble-text, $menu-collapse-focus-icon, $menu-collapse-text, $menu-highlight-background, $menu-highlight-icon, $menu-highlight-text, $menu-submenu-text, $menu-submenu-focus-text, $menu-submenu-background, $notification-color, $text-color;
 @use 'variables';
 @use 'mixins';
+@use 'tokens';
 
 /**
  * This function name uses British English to maintain backward compatibility, as developers
@@ -37,13 +38,27 @@ span.wp-media-buttons-icon:before {
 	color: currentColor;
 }
 
-.wp-core-ui .button-link {
-	color: variables.$link;
+/* Link button - appears as text link, no border or background */
+/* Matches Gutenberg's .is-link button variant */
+.wp-core-ui .button-link,
+.wp-core-ui .button.button-link {
+	color: var(--wp-admin-theme-color);
 
 	&:hover,
-	&:active,
+	&:active {
+		color: var(--wp-admin-theme-color-darker-20);
+	}
+
 	&:focus {
-		color: variables.$link-focus;
+		color: var(--wp-admin-theme-color);
+		border-radius: tokens.$radius-s;
+		box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
+		outline: 1px solid transparent;
+	}
+
+	&:disabled,
+	&[aria-disabled="true"] {
+		color: tokens.$gray-600;
 	}
 }
 
@@ -51,7 +66,7 @@ span.wp-media-buttons-icon:before {
 .media-modal .trash-attachment,
 .media-modal .untrash-attachment,
 .wp-core-ui .button-link-delete {
-	color: #a00;
+	color: tokens.$alert-red;
 }
 
 .media-modal .delete-attachment:hover,
@@ -62,7 +77,7 @@ span.wp-media-buttons-icon:before {
 .media-modal .untrash-attachment:focus,
 .wp-core-ui .button-link-delete:hover,
 .wp-core-ui .button-link-delete:focus {
-	color: #dc3232;
+	color: color.adjust(tokens.$alert-red, $lightness: 10%);
 }
 
 /* Forms */
@@ -109,79 +124,24 @@ textarea:focus {
 
 .wp-core-ui {
 
+	/* Default button - theme color border and text (matches secondary) */
 	.button {
-		border-color: #7e8993;
-		color: #32373c;
-	}
-
-	.button.hover,
-	.button:hover,
-	.button.focus,
-	.button:focus {
-		border-color: color.adjust(#7e8993, $lightness: -5%);
-		color: color.adjust(#32373c, $lightness: -5%);
-	}
-
-	.button.focus,
-	.button:focus {
-		border-color: #7e8993;
-		color: color.adjust(#32373c, $lightness: -5%);
-		box-shadow: 0 0 0 1px #32373c;
-	}
-
-	.button:active {
-		border-color: #7e8993;
-		color: color.adjust(#32373c, $lightness: -5%);
-		box-shadow: none;
-	}
-
-	.button.active,
-	.button.active:focus,
-	.button.active:hover {
-		border-color: variables.$button-color;
-		color: color.adjust(#32373c, $lightness: -5%);
-		box-shadow: inset 0 2px 5px -3px variables.$button-color;
+		@include mixins.button-secondary();
 	}
 
-	.button.active:focus {
-		box-shadow: 0 0 0 1px #32373c;
-	}
-
-	@if ( variables.$low-contrast-theme != "true" ) {
-		.button,
-		.button-secondary {
-			color: variables.$highlight-color;
-			border-color: variables.$highlight-color;
-		}
-
-		.button.hover,
-		.button:hover,
-		.button-secondary:hover{
-			border-color: color.adjust(variables.$highlight-color, $lightness: -10%);
-			color: color.adjust(variables.$highlight-color, $lightness: -10%);
-		}
-
-		.button.focus,
-		.button:focus,
-		.button-secondary:focus {
-			border-color: color.adjust(variables.$highlight-color, $lightness: 10%);
-			color: color.adjust(variables.$highlight-color, $lightness: -20%);
-			box-shadow: 0 0 0 1px color.adjust(variables.$highlight-color, $lightness: 10%);
-		}
-
-		.button-primary {
-			&:hover {
-				color: #fff;
-			}
-		}
+	/* Secondary button - same as default */
+	.button-secondary {
+		@include mixins.button-secondary();
 	}
 
+	/* Primary button - theme color background */
 	.button-primary {
 		@include mixins.button( variables.$button-color );
 	}
 
 	.button-group > .button.active {
-		border-color: variables.$button-color;
+		border-color: var(--wp-admin-theme-color);
+		background: rgba(var(--wp-admin-theme-color--rgb), 0.04);
 	}
 
 	.wp-ui-primary {
@@ -215,28 +175,34 @@ textarea:focus {
 
 
 /* List tables */
-@if variables.$low-contrast-theme == "true" {
-	.wrap .page-title-action:hover {
-		color: variables.$menu-text;
-		background-color: variables.$menu-background;
-	}
-} @else {
-	.wrap .page-title-action,
-	.wrap .page-title-action:active {
-		border: 1px solid variables.$highlight-color;
-		color: variables.$highlight-color;
-	}
 
-	.wrap .page-title-action:hover {
-		color: color.adjust(variables.$highlight-color, $lightness: -10%);
-		border-color: color.adjust(variables.$highlight-color, $lightness: -10%);
-	}
+// .page-title-action uses secondary button styling
+.wrap .page-title-action {
+	background: transparent;
+	border: 1px solid var(--wp-admin-theme-color);
+	border-radius: tokens.$radius-s;
+	color: var(--wp-admin-theme-color);
+}
 
-	.wrap .page-title-action:focus {
-		border-color: color.adjust(variables.$highlight-color, $lightness: 10%);
-		color: color.adjust(variables.$highlight-color, $lightness: -20%);
-		box-shadow: 0 0 0 1px color.adjust(variables.$highlight-color, $lightness: 10%);
-	}
+.wrap .page-title-action:hover {
+	background: rgba(var(--wp-admin-theme-color--rgb), 0.04);
+	border-color: var(--wp-admin-theme-color-darker-20);
+	color: var(--wp-admin-theme-color-darker-20);
+}
+
+.wrap .page-title-action:focus {
+	background: transparent;
+	border-color: var(--wp-admin-theme-color);
+	color: var(--wp-admin-theme-color);
+	box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
+	outline: 1px solid transparent;
+}
+
+.wrap .page-title-action:active {
+	background: rgba(var(--wp-admin-theme-color--rgb), 0.08);
+	border-color: var(--wp-admin-theme-color-darker-20);
+	color: var(--wp-admin-theme-color-darker-20);
+	box-shadow: none;
 }
 
 .view-switch a.current:before {
diff --git a/src/wp-admin/css/colors/_mixins.scss b/src/wp-admin/css/colors/_mixins.scss
index d33cf3bb2d854..d783bf268613e 100644
--- a/src/wp-admin/css/colors/_mixins.scss
+++ b/src/wp-admin/css/colors/_mixins.scss
@@ -1,39 +1,132 @@
 @use 'sass:color';
+@use 'tokens';
 
 /*
- * Button mixin- creates a button effect with correct
- * highlights/shadows, based on a base color.
+ * Button mixin - creates a primary button effect.
+ * Uses CSS custom properties for theme color support across color schemes.
  */
 @mixin button( $button-color, $button-text-color: #fff ) {
-	background: $button-color;
-	border-color: $button-color;
+	background: var(--wp-admin-theme-color);
+	border-color: transparent;
+	border-radius: tokens.$radius-s;
 	color: $button-text-color;
 
-	&:hover,
-	&:focus {
-		background: color.adjust($button-color, $lightness: 3%);
-		border-color: color.adjust($button-color, $lightness: -3%);
+	&:hover {
+		background: var(--wp-admin-theme-color-darker-10);
+		border-color: transparent;
 		color: $button-text-color;
 	}
 
 	&:focus {
+		background: var(--wp-admin-theme-color);
+		border-color: transparent;
+		color: $button-text-color;
+		/* Gutenberg-style focus ring: outer theme color + inset white for contrast */
 		box-shadow:
-			0 0 0 1px #fff,
-			0 0 0 3px $button-color;
+			0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color),
+			inset 0 0 0 1px tokens.$white;
+		/* Visible in Windows High Contrast mode */
+		outline: 1px solid transparent;
 	}
 
 	&:active {
-		background: color.adjust($button-color, $lightness: -5%);
-		border-color: color.adjust($button-color, $lightness: -5%);
+		background: var(--wp-admin-theme-color-darker-20);
+		border-color: transparent;
 		color: $button-text-color;
 	}
 
+	&:disabled,
+	&.disabled {
+		background: tokens.$gray-100;
+		border-color: transparent;
+		color: tokens.$gray-600;
+		cursor: not-allowed;
+	}
+
 	&.active,
 	&.active:focus,
 	&.active:hover {
-		background: $button-color;
+		background: var(--wp-admin-theme-color-darker-10);
 		color: $button-text-color;
-		border-color: color.adjust($button-color, $lightness: -15%);
-		box-shadow: inset 0 2px 5px -3px color.adjust($button-color, $lightness: -50%);
+		border-color: transparent;
+		box-shadow: none;
+	}
+}
+
+/*
+ * Secondary button mixin - outlined style with theme color.
+ * Matches Gutenberg's .is-secondary button variant.
+ */
+@mixin button-secondary() {
+	background: transparent;
+	border: 1px solid var(--wp-admin-theme-color);
+	border-radius: tokens.$radius-s;
+	color: var(--wp-admin-theme-color);
+
+	&:hover {
+		background: rgba(var(--wp-admin-theme-color--rgb), 0.04);
+		border-color: var(--wp-admin-theme-color-darker-20);
+		color: var(--wp-admin-theme-color-darker-20);
+	}
+
+	&:focus {
+		background: transparent;
+		border-color: var(--wp-admin-theme-color);
+		color: var(--wp-admin-theme-color);
+		box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
+		outline: 1px solid transparent;
+	}
+
+	&:active {
+		background: rgba(var(--wp-admin-theme-color--rgb), 0.08);
+		border-color: var(--wp-admin-theme-color-darker-20);
+		color: var(--wp-admin-theme-color-darker-20);
+		box-shadow: none;
+	}
+
+	&:disabled,
+	&.disabled {
+		background: transparent;
+		border-color: tokens.$gray-300;
+		color: tokens.$gray-600;
+		cursor: not-allowed;
+	}
+}
+
+/*
+ * Tertiary button mixin - transparent background, gray text.
+ */
+@mixin button-tertiary() {
+	background: transparent;
+	border: 1px solid tokens.$gray-600;
+	border-radius: tokens.$radius-s;
+	color: tokens.$gray-900;
+
+	&:hover {
+		background: rgba(0, 0, 0, 0.05);
+		border-color: tokens.$gray-700;
+		color: tokens.$gray-900;
+	}
+
+	&:focus {
+		background: transparent;
+		border-color: var(--wp-admin-theme-color);
+		color: tokens.$gray-900;
+		box-shadow: 0 0 0 var(--wp-admin-border-width-focus) var(--wp-admin-theme-color);
+		outline: 1px solid transparent;
+	}
+
+	&:active {
+		background: rgba(0, 0, 0, 0.1);
+		border-color: tokens.$gray-700;
+		color: tokens.$gray-900;
+	}
+
+	&:disabled,
+	&.disabled {
+		background: transparent;
+		border-color: tokens.$gray-400;
+		color: tokens.$gray-600;
+		cursor: not-allowed;
 	}
 }
diff --git a/src/wp-admin/css/colors/_tokens.scss b/src/wp-admin/css/colors/_tokens.scss
new file mode 100644
index 0000000000000..785f1f47f5076
--- /dev/null
+++ b/src/wp-admin/css/colors/_tokens.scss
@@ -0,0 +1,212 @@
+// ==========================================================================
+// WordPress Design System Tokens
+// ==========================================================================
+//
+// These tokens are derived from the WordPress Design System in Figma:
+// https://www.figma.com/design/804HN2REV2iap2ytjRQ055/WordPress-Design-System
+//
+// IMPORTANT: Do NOT expose these as CSS custom properties.
+// Use these Sass variables to compile to static CSS values.
+// The only CSS custom properties available are those in wp-base-styles:
+// - --wp-admin-theme-color
+// - --wp-admin-theme-color--rgb
+// - --wp-admin-theme-color-darker-10
+// - --wp-admin-theme-color-darker-20
+// - --wp-admin-border-width-focus
+//
+// ==========================================================================
+
+
+// --------------------------------------------------------------------------
+// Grid Units (Spacing)
+// --------------------------------------------------------------------------
+// Based on 4px base unit. Use for padding, margin, and gap values.
+
+$grid-unit-05: 4px;   // Scales/grid unit 05
+$grid-unit-10: 8px;   // Scales/grid unit 10
+$grid-unit-15: 12px;  // Scales/grid unit 15
+$grid-unit-20: 16px;  // Scales/grid unit 20
+$grid-unit-30: 24px;  // Scales/grid unit 30
+$grid-unit-40: 32px;  // Scales/grid unit 40
+$grid-unit-50: 40px;  // Scales/grid unit 50
+$grid-unit-60: 48px;  // Scales/grid unit 60
+$grid-unit-70: 56px;  // Scales/grid unit 70
+
+
+// --------------------------------------------------------------------------
+// Border Radius
+// --------------------------------------------------------------------------
+
+$radius-xs: 1px;      // radius-xs
+$radius-s: 2px;       // radius-s - Buttons, inputs
+$radius-m: 4px;       // radius-m - Focus rings
+$radius-l: 8px;       // radius-l - Cards, dashboard widgets
+$radius-30: 12px;     // Radius 30
+$radius-full: 9999px; // radius-full - Pills, avatars, circles
+
+
+// --------------------------------------------------------------------------
+// Gray Scale
+// --------------------------------------------------------------------------
+// Neutral colors for backgrounds, borders, and text.
+
+$gray-100: #f0f0f0;   // Scales/Grays/gray-100 - Page background, disabled inputs
+$gray-200: #e0e0e0;   // Scales/Grays/gray-200
+$gray-300: #dddddd;   // Scales/Grays/gray-300
+$gray-400: #cccccc;   // Scales/Grays/gray-400 - Disabled borders
+$gray-600: #949494;   // Scales/Grays/gray-600 - Input borders, disabled text
+$gray-700: #757575;   // Scales/Grays/gray-700
+$gray-800: #2f2f2f;   // Scales/Grays/gray-800
+$gray-900: #1e1e1e;   // Scales/Grays/gray-900 - Primary text
+
+$white: #ffffff;      // Scales/Black & White/white
+
+
+// --------------------------------------------------------------------------
+// Theme Colors (Static reference values)
+// --------------------------------------------------------------------------
+// For actual theme color usage, use var(--wp-admin-theme-color) instead.
+// These are provided for reference and for contexts where CSS vars aren't available.
+
+$theme-reference: #3858e9;           // Scales/Theme/theme (modern scheme)
+$theme-darker-10-reference: #2145e6; // Scales/Theme/theme-darker-10
+$theme-darker-20-reference: #183ad6; // Scales/Theme/theme-darker-20
+$theme-alpha-04: rgba(56, 88, 233, 0.04); // Scales/Theme/theme-alpha-04 (4% opacity)
+$theme-alpha-08: rgba(56, 88, 233, 0.08); // Scales/Theme/theme-alpha-08 (8% opacity)
+
+$brand-9: #4465db;    // Scales/brand-9 - Focus ring color (static, not theme-dependent)
+
+
+// --------------------------------------------------------------------------
+// Semantic Colors
+// --------------------------------------------------------------------------
+// Use these for notices, alerts, and status indicators.
+// These are intentionally NOT theme-dependent for consistency.
+
+$alert-yellow: #f0b849;    // Scales/Yellow/alert-yellow - Warnings
+$alert-green: #4ab866;     // Scales/Green/alert-green - Success
+$alert-red: #cc1818;       // Scales/Red/alert-red - Errors
+$alert-blue: #3858e9;      // Info notices (matches modern theme)
+
+// Background tints for notices
+$alert-yellow-bg: #fef8ee; // Warning notice background
+$alert-green-bg: #eff9f1;  // Success notice background
+$alert-red-bg: #fcf0f0;    // Error notice background
+
+$synced-color: #7a00df;    // Scales/Purple/--wp-block-synced-color
+
+
+// --------------------------------------------------------------------------
+// Text Colors
+// --------------------------------------------------------------------------
+
+$text-primary: $gray-900;     // Primary text color
+$text-secondary: $gray-700;   // Secondary text
+$text-tertiary: #5d5d5d;      // Alias/text/text-tertiary - Placeholder, hints
+$text-disabled: $gray-600;    // Disabled text
+
+
+// --------------------------------------------------------------------------
+// Component Tokens
+// --------------------------------------------------------------------------
+
+// Inputs
+$input-bg: $white;                    // Alias/bg/bg-input
+$input-border-color: $gray-600;       // Default input border
+$input-border-color-disabled: $gray-400;
+$input-bg-disabled: $gray-100;
+$input-border-width-default: 1px;     // Input/Default
+$input-border-width-focus: 1.5px;     // Input/Focus
+$field-spacing-horizontal: 8px;       // Alias/field-spacing-horizontal
+
+// Checkboxes and Radios
+$checkbox-size: 16px;                 // Alias/checkbox
+$radio-size: 16px;                    // Alias/radio
+
+// Toggles
+$toggle-width: 32px;                  // Alias/toggle-width
+$toggle-height: 16px;                 // Alias/toggle-height
+
+// Buttons
+// Note: Gutenberg is transitioning to 40px as the default button size.
+// The "compact" size (32px) is available for space-constrained contexts.
+$button-height-default: 40px;         // Default button height (next-default-40px)
+$button-height-compact: 32px;         // Compact button height
+$button-height-small: 24px;           // Small button height
+
+// Cards and Surfaces
+$card-bg: $white;
+$card-border-color: rgba(0, 0, 0, 0.1);
+$card-border-width: 1px;
+$card-border-radius: $radius-l;           // 8px for dashboard widgets
+$card-border-radius-metabox: 0;           // 0 for post editor metaboxes
+$card-divider-color: rgba(0, 0, 0, 0.1);
+
+// Card Padding Sizes
+$card-padding-xs: $grid-unit-10;          // 8px - xSmall cards
+$card-padding-sm: $grid-unit-20;          // 16px - Small cards (metaboxes, dashboard widgets)
+$card-padding-md-h: $grid-unit-30;        // 24px - Medium cards horizontal
+$card-padding-md-v: $grid-unit-20;        // 16px - Medium cards vertical
+$card-padding-lg-h: $grid-unit-40;        // 32px - Large cards horizontal
+$card-padding-lg-v: $grid-unit-30;        // 24px - Large cards vertical
+
+// Page Layout
+$page-padding-large: 48px;            // Alias/page-large
+$page-padding-small: 24px;            // Alias/page-small
+
+
+// --------------------------------------------------------------------------
+// Typography Scale
+// --------------------------------------------------------------------------
+
+// Font Sizes
+$font-size-xs: 11px;    // xs - Small labels, button small
+$font-size-s: 12px;     // s - Body small
+$font-size-m: 13px;     // m - Base body text, buttons
+$font-size-l: 15px;     // l - Body large, heading large
+$font-size-xl: 20px;    // xl - Heading XL
+
+// Line Heights
+$line-height-xs: 16px;  // xs
+$line-height-s: 20px;   // s - Most UI elements
+$line-height-m: 24px;   // m - Body large
+
+// Font Weights
+$font-weight-regular: 400;  // Regular - Body text
+$font-weight-medium: 500;   // Medium - Headings, buttons
+
+
+// --------------------------------------------------------------------------
+// Elevation (Box Shadows)
+// --------------------------------------------------------------------------
+
+$elevation-xs:
+  0 4px 4px rgba(0, 0, 0, 0.01),
+  0 3px 3px rgba(0, 0, 0, 0.02),
+  0 1px 2px rgba(0, 0, 0, 0.02),
+  0 1px 1px rgba(0, 0, 0, 0.03);
+
+$elevation-s:
+  0 8px 8px rgba(0, 0, 0, 0.02),
+  0 1px 2px rgba(0, 0, 0, 0.05);
+
+$elevation-m:
+  0 16px 16px rgba(0, 0, 0, 0.02),
+  0 4px 5px rgba(0, 0, 0, 0.03),
+  0 2px 3px rgba(0, 0, 0, 0.05);
+
+$elevation-l:
+  0 50px 43px rgba(0, 0, 0, 0.02),
+  0 30px 36px rgba(0, 0, 0, 0.04),
+  0 15px 27px rgba(0, 0, 0, 0.07),
+  0 5px 15px rgba(0, 0, 0, 0.08);
+
+
+// --------------------------------------------------------------------------
+// Layout
+// --------------------------------------------------------------------------
+
+$modal-width-small: 384px;    // Layout/Modal small
+$modal-width-medium: 512px;   // Layout/Modal medium
+$modal-width-large: 840px;    // Layout/Modal large
+
diff --git a/src/wp-admin/css/colors/_variables.scss b/src/wp-admin/css/colors/_variables.scss
index 8a073f830e4b6..d37c2b1392f00 100644
--- a/src/wp-admin/css/colors/_variables.scss
+++ b/src/wp-admin/css/colors/_variables.scss
@@ -1,5 +1,8 @@
 @use "sass:color";
 
+// Import design system tokens
+@use "tokens" as *;
+
 // assign default value to all undefined variables
 
 $scheme-name: "default" !default;
@@ -15,7 +18,7 @@ $notification-color: #d54e21 !default;
 
 // global
 
-$body-background: #f1f1f1 !default;
+$body-background: $gray-100 !default;
 
 $link: #0073aa !default;
 $link-focus: color.adjust($link, $lightness: 10%) !default;
diff --git a/src/wp-admin/css/common.css b/src/wp-admin/css/common.css
index e062a471d7150..393787f8e6c2a 100644
--- a/src/wp-admin/css/common.css
+++ b/src/wp-admin/css/common.css
@@ -631,11 +631,12 @@ code {
 	top: -3px;
 	margin-left: 4px;
 	border: 1px solid #2271b1;
-	border-radius: 3px;
-	background: #f6f7f7;
+	border-radius: 2px;
+	background: transparent;
 	font-size: 13px;
-	font-weight: 400;
-	line-height: 2.15384615;
+	font-weight: 500;
+	min-height: 40px;
+	line-height: 2.92307692; /* 38px for 40px height */
 	color: #2271b1; /* use the standard color used for buttons */
 	padding: 0 10px;
 	min-height: 30px;
@@ -649,7 +650,6 @@ code {
 
 .wrap .add-new-h2:hover, /* deprecated */
 .wrap .page-title-action:hover {
-	background: #f0f0f1;
 	border-color: #0a4b78;
 	color: #0a4b78;
 }
diff --git a/src/wp-admin/css/themes.css b/src/wp-admin/css/themes.css
index ea62a09cf1ed1..113cec87f50e7 100644
--- a/src/wp-admin/css/themes.css
+++ b/src/wp-admin/css/themes.css
@@ -83,7 +83,7 @@ body.js .theme-browser.search-loading {
 	font-weight: 600;
 	height: 18px;
 	margin: 0;
-	padding: 15px;
+	padding: 16px 15px;
 	box-shadow: inset 0 1px 0 rgba(0, 0, 0, 0.1);
 	overflow: hidden;
 	white-space: nowrap;
@@ -112,9 +112,26 @@ body.js .theme-browser.search-loading {
 	margin-right: 3px;
 }
 
+/* Use compact size for space-constrained theme cards */
 .theme-browser .theme .theme-actions .button {
 	float: none;
 	margin-left: 3px;
+	min-height: 32px;
+	line-height: 2.30769231; /* 30px for 32px min-height */
+	padding: 0 12px;
+}
+
+/* Secondary buttons need white background for visibility on semi-transparent overlay */
+.theme-browser .theme .theme-actions .button:not(.button-primary) {
+	background: #fff;
+}
+
+.theme-browser .theme .theme-actions .button:not(.button-primary):hover {
+	background: #f0f0f0;
+}
+
+.theme-browser .theme .theme-actions .button:not(.button-primary):focus {
+	background: #fff;
 }
 
 /**
@@ -211,7 +228,7 @@ body.js .theme-browser.search-loading {
 .theme-browser .theme.active .theme-name {
 	background: #1d2327;
 	color: #fff;
-	padding-right: 110px;
+	padding-right: 115px;
 	font-weight: 300;
 	box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.5);
 }
@@ -240,7 +257,7 @@ body.js .theme-browser.search-loading {
 	top: 50%;
 	transform: translateY(-50%);
 	right: 0;
-	padding: 9px 15px;
+	padding: 9px 12px;
 	box-shadow: inset 0 1px 0 rgba(0, 0, 0, 0.1);
 }
 
@@ -248,6 +265,19 @@ body.js .theme-browser.search-loading {
 	margin-right: 0;
 }
 
+/* Active theme secondary buttons need white background for visibility on dark overlay */
+.theme-browser .theme.active .theme-actions .button:not(.button-primary) {
+	background: #fff;
+}
+
+.theme-browser .theme.active .theme-actions .button:not(.button-primary):hover {
+	background: #f0f0f0;
+}
+
+.theme-browser .theme.active .theme-actions .button:not(.button-primary):focus {
+	background: #fff;
+}
+
 .theme-browser .theme .theme-author {
 	background: #1d2327;
 	color: #f0f0f1;
diff --git a/src/wp-includes/css/buttons.css b/src/wp-includes/css/buttons.css
index 5146be4274254..3eda51ae5d788 100644
--- a/src/wp-includes/css/buttons.css
+++ b/src/wp-includes/css/buttons.css
@@ -46,15 +46,16 @@ TABLE OF CONTENTS:
 	display: inline-block;
 	text-decoration: none;
 	font-size: 13px;
-	line-height: 2.15384615; /* 28px */
-	min-height: 30px;
+	font-weight: 500;
+	line-height: 2.92307692; /* 38px - allows 40px min-height with 1px border */
+	min-height: 40px;
 	margin: 0;
-	padding: 0 10px;
+	padding: 0 16px;
 	cursor: pointer;
 	border-width: 1px;
 	border-style: solid;
 	-webkit-appearance: none;
-	border-radius: 3px;
+	border-radius: 2px;
 	white-space: nowrap;
 	box-sizing: border-box;
 }
@@ -69,26 +70,36 @@ TABLE OF CONTENTS:
 	padding: 0;
 }
 
-.wp-core-ui .button.button-large,
-.wp-core-ui .button-group.button-large .button {
+/* Compact size - 32px, for space-constrained contexts */
+.wp-core-ui .button.button-compact,
+.wp-core-ui .button-group.button-compact .button {
+	line-height: 2.30769231; /* 30px - allows 32px min-height with 1px border */
 	min-height: 32px;
-	line-height: 2.30769231; /* 30px */
 	padding: 0 12px;
 }
 
+/* Small size - 24px */
 .wp-core-ui .button.button-small,
 .wp-core-ui .button-group.button-small .button {
-	min-height: 26px;
-	line-height: 2.18181818; /* 24px */
+	line-height: 2; /* 22px - allows 24px min-height with 1px border */
+	min-height: 24px;
 	padding: 0 8px;
 	font-size: 11px;
 }
 
+/* Large size - explicit 40px (same as default, for semantic clarity) */
+.wp-core-ui .button.button-large,
+.wp-core-ui .button-group.button-large .button {
+	line-height: 2.92307692; /* 38px - allows 40px min-height with 1px border */
+	min-height: 40px;
+	padding: 0 16px;
+}
+
 .wp-core-ui .button.button-hero,
 .wp-core-ui .button-group.button-hero .button {
 	font-size: 14px;
-	min-height: 46px;
-	line-height: 3.14285714;
+	line-height: 3.28571429; /* 46px - allows 48px min-height with 1px border */
+	min-height: 48px;
 	padding: 0 36px;
 }
 
@@ -115,9 +126,9 @@ TABLE OF CONTENTS:
 
 .wp-core-ui .button,
 .wp-core-ui .button-secondary {
-	color: #2271b1;
-	border-color: #2271b1;
-	background: #f6f7f7;
+	color: #3858e9;
+	border-color: #3858e9;
+	background: transparent;
 	vertical-align: top;
 }
 
@@ -127,21 +138,21 @@ TABLE OF CONTENTS:
 
 .wp-core-ui .button.hover,
 .wp-core-ui .button:hover,
-.wp-core-ui .button-secondary:hover{
-	background: #f0f0f1;
-	border-color: #0a4b78;
-	color: #0a4b78;
+.wp-core-ui .button-secondary:hover {
+	background: rgba(56, 88, 233, 0.04);
+	border-color: #183ad6;
+	color: #183ad6;
 }
 
 .wp-core-ui .button.focus,
 .wp-core-ui .button:focus,
 .wp-core-ui .button-secondary:focus {
-	background: #f6f7f7;
-	border-color: #3582c4;
-	color: #0a4b78;
-	box-shadow: 0 0 0 1px #3582c4;
+	background: transparent;
+	border-color: #3858e9;
+	color: #3858e9;
+	box-shadow: 0 0 0 var(--wp-admin-border-width-focus, 1.5px) #3858e9;
 	/* Only visible in Windows High Contrast mode */
-	outline: 2px solid transparent;
+	outline: 1px solid transparent;
 	/* Reset inherited offset from Gutenberg */
 	outline-offset: 0;
 }
@@ -149,25 +160,24 @@ TABLE OF CONTENTS:
 /* :active state */
 .wp-core-ui .button:active,
 .wp-core-ui .button-secondary:active {
-	background: #f6f7f7;
-	border-color: #8c8f94;
+	background: rgba(56, 88, 233, 0.08);
+	border-color: #183ad6;
+	color: #183ad6;
 	box-shadow: none;
 }
 
 /* pressed state e.g. a selected setting */
 .wp-core-ui .button.active,
 .wp-core-ui .button.active:hover {
-	background-color: #dcdcde;
-	color: #135e96;
-	border-color: #0a4b78;
-	box-shadow: inset 0 2px 5px -3px #0a4b78;
+	background-color: rgba(56, 88, 233, 0.04);
+	color: #3858e9;
+	border-color: #3858e9;
+	box-shadow: none;
 }
 
 .wp-core-ui .button.active:focus {
-	border-color: #3582c4;
-	box-shadow:
-		inset 0 2px 5px -3px #0a4b78,
-		0 0 0 1px #3582c4;
+	border-color: #3858e9;
+	box-shadow: 0 0 0 var(--wp-admin-border-width-focus, 1.5px) #3858e9;
 }
 
 .wp-core-ui .button[disabled],
@@ -177,9 +187,9 @@ TABLE OF CONTENTS:
 .wp-core-ui .button-secondary:disabled,
 .wp-core-ui .button-secondary.disabled,
 .wp-core-ui .button-disabled {
-	color: #a7aaad !important;
-	border-color: #dcdcde !important;
-	background: #f6f7f7 !important;
+	color: #949494 !important;
+	border-color: #dddddd !important;
+	background: transparent !important;
 	box-shadow: none !important;
 	cursor: default;
 	transform: none !important;
@@ -201,7 +211,7 @@ TABLE OF CONTENTS:
 	cursor: pointer;
 	text-align: left;
 	/* Mimics the default link style in common.css */
-	color: #2271b1;
+	color: #3858e9;
 	text-decoration: underline;
 	transition-property: border, background, color;
 	transition-duration: .05s;
@@ -210,14 +220,15 @@ TABLE OF CONTENTS:
 
 .wp-core-ui .button-link:hover,
 .wp-core-ui .button-link:active {
-	color: #135e96;
+	color: #183ad6;
 }
 
 .wp-core-ui .button-link:focus {
-	color: #043959;
-	box-shadow: 0 0 0 2px #2271b1;
+	color: #3858e9;
+	box-shadow: 0 0 0 var(--wp-admin-border-width-focus, 1.5px) #3858e9;
+	border-radius: 2px;
 	/* Only visible in Windows High Contrast mode */
-	outline: 2px solid transparent;
+	outline: 1px solid transparent;
 }
 
 .wp-core-ui .button-link-delete {
@@ -241,35 +252,37 @@ TABLE OF CONTENTS:
 ---------------------------------------------------------------------------- */
 
 .wp-core-ui .button-primary {
-	background: #2271b1;
-	border-color: #2271b1;
+	background: #3858e9;
+	border-color: #3858e9;
 	color: #fff;
 	text-decoration: none;
 	text-shadow: none;
 }
 
 .wp-core-ui .button-primary.hover,
-.wp-core-ui .button-primary:hover,
-.wp-core-ui .button-primary.focus,
-.wp-core-ui .button-primary:focus {
-	background: #135e96;
-	border-color: #135e96;
+.wp-core-ui .button-primary:hover {
+	background: #2145e6;
+	border-color: #2145e6;
 	color: #fff;
 }
 
 .wp-core-ui .button-primary.focus,
 .wp-core-ui .button-primary:focus {
+	background: #3858e9;
+	border-color: #3858e9;
+	color: #fff;
 	box-shadow:
-		0 0 0 1px #fff,
-		0 0 0 3px #2271b1;
+		0 0 0 var(--wp-admin-border-width-focus, 1.5px) #3858e9,
+		inset 0 0 0 1px #fff;
+	outline: 1px solid transparent;
 }
 
 .wp-core-ui .button-primary.active,
 .wp-core-ui .button-primary.active:hover,
 .wp-core-ui .button-primary.active:focus,
 .wp-core-ui .button-primary:active {
-	background: #135e96;
-	border-color: #135e96;
+	background: #183ad6;
+	border-color: #183ad6;
 	box-shadow: none;
 	color: #fff;
 }
@@ -278,9 +291,9 @@ TABLE OF CONTENTS:
 .wp-core-ui .button-primary:disabled,
 .wp-core-ui .button-primary-disabled,
 .wp-core-ui .button-primary.disabled {
-	color: #a7aaad !important;
-	background: #f6f7f7 !important;
-	border-color: #dcdcde !important;
+	color: #949494 !important;
+	background: #f0f0f0 !important;
+	border-color: #f0f0f0 !important;
 	box-shadow: none !important;
 	text-shadow: none !important;
 	cursor: default;
@@ -309,11 +322,11 @@ TABLE OF CONTENTS:
 }
 
 .wp-core-ui .button-group > .button:first-child {
-	border-radius: 3px 0 0 3px;
+	border-radius: 2px 0 0 2px;
 }
 
 .wp-core-ui .button-group > .button:last-child {
-	border-radius: 0 3px 3px 0;
+	border-radius: 0 2px 2px 0;
 }
 
 .wp-core-ui .button-group > .button-primary + .button {
@@ -353,7 +366,7 @@ TABLE OF CONTENTS:
 	input#save-post,
 	a.preview {
 		padding: 0 14px;
-		line-height: 2.71428571; /* 38px */
+		line-height: 2.71428571; /* 38px - allows 40px min-height with 1px border */
 		font-size: 14px;
 		vertical-align: middle;
 		min-height: 40px;
@@ -366,9 +379,9 @@ TABLE OF CONTENTS:
 	}
 
 	#media-upload.wp-core-ui .button {
-		padding: 0 10px 1px;
+		padding: 0 10px;
+		line-height: 1.69230769; /* 22px */
 		min-height: 24px;
-		line-height: 22px;
 		font-size: 13px;
 	}
 
@@ -386,8 +399,8 @@ TABLE OF CONTENTS:
 
 	.wp-core-ui.wp-customizer .button {
 		font-size: 13px;
-		line-height: 2.15384615; /* 28px */
-		min-height: 30px;
+		line-height: 2.30769231; /* 30px */
+		min-height: 32px;
 		margin: 0;
 		vertical-align: inherit;
 	}
@@ -404,9 +417,9 @@ TABLE OF CONTENTS:
 	/* Reset responsive styles on Log in button on iframed login form */
 
 	.interim-login .button.button-large {
-		min-height: 30px;
-		line-height: 2;
-		padding: 0 12px 2px;
+		min-height: 32px;
+		line-height: 2.30769231; /* 30px */
+		padding: 0 12px;
 	}
 
 }