diff --git a/packages/site_shared/lib/_sass/components/_site-switcher.scss b/packages/site_shared/lib/_sass/components/_site-switcher.scss
index 07b6fad530..ac4f4cc9f0 100644
--- a/packages/site_shared/lib/_sass/components/_site-switcher.scss
+++ b/packages/site_shared/lib/_sass/components/_site-switcher.scss
@@ -31,7 +31,7 @@
   font-size: 1.75rem;
   line-height: 1.25em;
   letter-spacing: 0.015em;
-  font-family: 'Google Sans', sans-serif;
+  font-family: var(--site-ui-fontFamily);
   user-select: none;
 
   >img {
diff --git a/packages/site_shared/lib/_sass/components/_summary-card.scss b/packages/site_shared/lib/_sass/components/_summary-card.scss
index a49bf5b13d..17773ccc6b 100644
--- a/packages/site_shared/lib/_sass/components/_summary-card.scss
+++ b/packages/site_shared/lib/_sass/components/_summary-card.scss
@@ -17,7 +17,7 @@
     h3 {
       margin: 0;
       font-size: 1.25rem;
-      font-weight: 700;
+      font-weight: 600;
       color: var(--site-base-fgColor);
     }
 
diff --git a/packages/site_shared/lib/src/layouts/dash_layout.dart b/packages/site_shared/lib/src/layouts/dash_layout.dart
index 3cb1085b11..715381107a 100644
--- a/packages/site_shared/lib/src/layouts/dash_layout.dart
+++ b/packages/site_shared/lib/src/layouts/dash_layout.dart
@@ -44,12 +44,12 @@ abstract class DashLayout implements PageLayout {
   ({Set<String> prerender, Set<String> prefetch}) speculationUrls(Page page) =>
       const (prerender: {}, prefetch: {});
 
-  List<String> get fonts => [
-    'https://fonts.googleapis.com/css2?family=Google+Sans:wght@400;500;700&display=swap',
-    'https://fonts.googleapis.com/css2?family=Google+Sans+Mono:wght@400;500;700&display=swap',
-    'https://fonts.googleapis.com/css2?family=Google+Sans+Text:wght@400;500;700&display=swap',
+  /// Font stylesheet URLs to load in the document head before site styles.
+  ///
+  /// Override this to add, remove, or replace site-level font resources.
+  List<String> get fontUrls => const [
+    'https://fonts.googleapis.com/css2?family=Google+Sans+Flex:opsz,wght@6..72,400..700&family=Google+Sans+Code:ital,wght@0,400..700;1,400..700&display=swap',
     'https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@24,400,0..1,0',
-    'https://fonts.googleapis.com/css2?family=Noto+Serif:ital,wght@0,100..900;1,100..900&display=swap',
   ];
 
   String get stylesHash;
@@ -142,7 +142,7 @@ abstract class DashLayout implements PageLayout {
         href: 'https://fonts.gstatic.com',
         attributes: {'crossorigin': ''},
       ),
-      for (final font in fonts) link(rel: 'stylesheet', href: font),
+      for (final font in fontUrls) link(rel: 'stylesheet', href: font),
 
       // Set site styles.
       link(
diff --git a/sites/docs/lib/_sass/base/_root.scss b/sites/docs/lib/_sass/base/_root.scss
index 14dff029b2..4e302a796c 100644
--- a/sites/docs/lib/_sass/base/_root.scss
+++ b/sites/docs/lib/_sass/base/_root.scss
@@ -5,10 +5,11 @@ $base_primary_color: #0468D7;
 // Root variables shared by both light and dark mode.
 body {
   // Site typography.
-  --site-ui-fontFamily: 'Google Sans', 'Roboto', ui-sans, sans-serif;
-  --site-body-fontFamily: 'Google Sans Text', 'Roboto', ui-sans, sans-serif;
-  --site-code-fontFamily: 'Google Sans Mono', 'Roboto Mono', ui-monospace, monospace;
+  --site-ui-fontFamily: 'Google Sans Flex', 'Roboto', ui-sans, sans-serif;
+  --site-body-fontFamily: 'Google Sans Flex', 'Roboto', ui-sans, sans-serif;
+  --site-code-fontFamily: 'Google Sans Code', 'Roboto Mono', ui-monospace, monospace;
   --site-icon-fontFamily: 'Material Symbols Outlined', 'Material Symbols', 'Material Icons';
+  font-optical-sizing: auto;
 
   // Site layout sizes.
   --site-header-height: 4rem;
diff --git a/sites/docs/lib/_sass/components/_content.scss b/sites/docs/lib/_sass/components/_content.scss
index 0800aeb3e3..9420072925 100644
--- a/sites/docs/lib/_sass/components/_content.scss
+++ b/sites/docs/lib/_sass/components/_content.scss
@@ -106,7 +106,7 @@ main {
 
   b,
   strong {
-    font-weight: bolder;
+    font-weight: 600;
   }
 
   h1,
diff --git a/sites/docs/lib/_sass/components/_sidebar.scss b/sites/docs/lib/_sass/components/_sidebar.scss
index ffa324a545..0b0168427e 100644
--- a/sites/docs/lib/_sass/components/_sidebar.scss
+++ b/sites/docs/lib/_sass/components/_sidebar.scss
@@ -46,7 +46,7 @@
   }
 
   .nav-header {
-    font-weight: bolder;
+    font-weight: 650;
     font-size: 1rem;
     padding: 0.25rem 0.4rem 0;
     color: var(--site-base-fgColor-lighter);
diff --git a/sites/docs/lib/_sass/pages/_learning-resources-index.scss b/sites/docs/lib/_sass/pages/_learning-resources-index.scss
index 3527fa4ca8..0e6581adbd 100644
--- a/sites/docs/lib/_sass/pages/_learning-resources-index.scss
+++ b/sites/docs/lib/_sass/pages/_learning-resources-index.scss
@@ -130,7 +130,7 @@
     color: var(--site-base-fgColor-alt);
     background-color: var(--site-raised-bgColor);
     font-family: var(--site-ui-fontFamily);
-    font-weight: 700;
+    font-weight: 600;
     font-size: .925rem;
     padding: .5rem;
     border-bottom: 1px solid var(--site-inset-borderColor);