feat(a11y): add dynamic font scaling (#28314)

Issue number: resolves #24638, resolves #18592

---------

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issue. -->

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etc). Submit multiple pull requests if needed. -->

## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

Developers have requested that Ionic Framework support the dynamic type
feature on iOS for accessibility purposes. Ionic applications do not
respond to font scaling on iOS which can create inaccessible
applications particularly for users with low vision. Ionic apps on
Android devices currently support the Android equivalent due to
functionality in the Chromium webview.

Developers have also requested a way of adjusting the fonts in their
Ionic UI components consistently.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Ionic components now use `rem` instead of `px` where appropriate. This
means devs can change the font size on `html` and the text in supported
Ionic components will scale up/down appropriately
- Add support for Dynamic Type on iOS (the iOS version of Dynamic Font
Scaling)

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

<!-- If this introduces a breaking change, please describe the impact
and migration path for existing applications below. -->


## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->

---------

Co-authored-by: Maria Hutt <thetaPC@users.noreply.github.com>
Co-authored-by: Brandy Carney <brandyscarney@users.noreply.github.com>
Co-authored-by: Shawn Taylor <shawn@ionic.io>
Co-authored-by: ionitron <hi@ionicframework.com>
Co-authored-by: Sean Perkins <sean@ionic.io>
Co-authored-by: Sean Perkins <13732623+sean-perkins@users.noreply.github.com>
Co-authored-by: Amanda Johnston <90629384+amandaejohnston@users.noreply.github.com>

core/src/components/action-sheet/action-sheet.ios.scss

@@ -131,11 +131,11 @@
 .action-sheet-button {
   @include padding($action-sheet-ios-button-padding);
 
-  height: $action-sheet-ios-button-height;
+  min-height: $action-sheet-ios-button-height;
 
   font-size: $action-sheet-ios-button-font-size;
 
-  contain: strict;
+  contain: content;
 }
 
 .action-sheet-button .action-sheet-icon {

core/src/components/action-sheet/action-sheet.ios.vars.scss

@@ -50,7 +50,7 @@ $action-sheet-ios-title-padding-start:                            $action-sheet-
 $action-sheet-ios-title-color:                                    $text-color-step-600 !default;
 
 /// @prop - Font size of the action sheet title
-$action-sheet-ios-title-font-size:                                13px !default;
+$action-sheet-ios-title-font-size:                                dynamic-font-min(1, 13px) !default;
 
 /// @prop - Font weight of the action sheet title
 $action-sheet-ios-title-font-weight:                              400 !default;
@@ -75,7 +75,7 @@ $action-sheet-ios-title-border-color:                             rgba($text-col
 // --------------------------------------------------
 
 /// @prop - Font size of the action sheet sub title
-$action-sheet-ios-sub-title-font-size:                            13px !default;
+$action-sheet-ios-sub-title-font-size:                            dynamic-font-min(1, 13px) !default;
 
 /// @prop - Padding top of the action sheet sub title
 $action-sheet-ios-sub-title-padding-top:                          6px !default;
@@ -97,19 +97,19 @@ $action-sheet-ios-sub-title-padding-start:                        $action-sheet-
 $action-sheet-ios-button-height:                                  56px !default;
 
 /// @prop - Padding of the action sheet button
-$action-sheet-ios-button-padding:                                 18px !default;
+$action-sheet-ios-button-padding:                                 14px !default;
 
 /// @prop - Text color of the action sheet button
 $action-sheet-ios-button-text-color:                              ion-color(primary, base) !default;
 
 /// @prop - Font size of the action sheet button icon
-$action-sheet-ios-button-icon-font-size:                          28px !default;
+$action-sheet-ios-button-icon-font-size:                          dynamic-font-min(1, 28px) !default;
 
 /// @prop - Padding right of the action sheet button icon
 $action-sheet-ios-button-icon-padding-right:                      .3em !default;
 
 /// @prop - Font size of the action sheet button
-$action-sheet-ios-button-font-size:                               20px !default;
+$action-sheet-ios-button-font-size:                               dynamic-font-min(1, 20px) !default;
 
 /// @prop - Border color alpha of the action sheet button
 $action-sheet-ios-button-border-color-alpha:                      .08 !default;

core/src/components/action-sheet/action-sheet.md.scss

@@ -67,13 +67,13 @@
 
   position: relative;
 
-  height: $action-sheet-md-button-height;
+  min-height: $action-sheet-md-button-height;
 
   font-size: $action-sheet-md-button-font-size;
 
   text-align: $action-sheet-md-text-align;
 
-  contain: strict;
+  contain: content;
   overflow: hidden;
 }
 

core/src/components/action-sheet/action-sheet.md.vars.scss

@@ -26,7 +26,7 @@ $action-sheet-md-title-height:                          60px !default;
 $action-sheet-md-title-color:                           rgba($text-color-rgb, 0.54) !default;
 
 /// @prop - Font size of the action sheet title
-$action-sheet-md-title-font-size:                       16px !default;
+$action-sheet-md-title-font-size:                       dynamic-font(16px) !default;
 
 /// @prop - Padding top of the action sheet title
 $action-sheet-md-title-padding-top:                     20px !default;
@@ -45,7 +45,7 @@ $action-sheet-md-title-padding-start:                   $action-sheet-md-title-p
 // --------------------------------------------------
 
 /// @prop - Font size of the action sheet sub title
-$action-sheet-md-sub-title-font-size:                   14px !default;
+$action-sheet-md-sub-title-font-size:                   dynamic-font(14px) !default;
 
 /// @prop - Padding top of the action sheet sub title
 $action-sheet-md-sub-title-padding-top:                 16px !default;
@@ -70,10 +70,10 @@ $action-sheet-md-button-height:                         52px !default;
 $action-sheet-md-button-text-color:                     $text-color-step-150 !default;
 
 /// @prop - Font size of the action sheet button
-$action-sheet-md-button-font-size:                      16px !default;
+$action-sheet-md-button-font-size:                      dynamic-font(16px) !default;
 
 /// @prop - Padding top of the action sheet button
-$action-sheet-md-button-padding-top:                    0 !default;
+$action-sheet-md-button-padding-top:                    12px !default;
 
 /// @prop - Padding end of the action sheet button
 $action-sheet-md-button-padding-end:                    16px !default;
@@ -91,7 +91,7 @@ $action-sheet-md-button-background:                     transparent !default;
 // --------------------------------------------------
 
 /// @prop - Font size of the icon in the action sheet button
-$action-sheet-md-icon-font-size:                        24px !default;
+$action-sheet-md-icon-font-size:                        dynamic-font(24px) !default;
 
 /// @prop - Margin top of the icon in the action sheet button
 $action-sheet-md-icon-margin-top:                       0 !default;

core/src/components/action-sheet/action-sheet.scss

@@ -126,7 +126,10 @@
   justify-content: flex-end;
 
   height: 100%;
+
+  /* Fallback for browsers that do not support dvh */
   max-height: 100vh;
+  max-height: 100dvh;
 }
 
 .action-sheet-group {

core/src/components/action-sheet/test/a11y/action-sheet.e2e.ts

@@ -86,3 +86,37 @@ configs({ directions: ['ltr'] }).forEach(({ config, title }) => {
     });
   });
 });
+
+configs({ directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
+  test.describe(title('action-sheet: font scaling'), () => {
+    test('should scale text on larger font sizes', async ({ page }) => {
+      await page.setContent(
+        `
+        <style>
+          html {
+            font-size: 36px;
+          }
+        </style>
+
+        <ion-action-sheet></ion-action-sheet>
+
+        <script>
+          const actionSheet = document.querySelector('ion-action-sheet');
+          actionSheet.header = 'Header';
+          actionSheet.subHeader = 'Sub Header';
+          actionSheet.buttons = ['Ok', { role: 'cancel', text: 'Cancel' }];
+        </script>
+      `,
+        config
+      );
+
+      const ionActionSheetDidPresent = await page.spyOnEvent('ionActionSheetDidPresent');
+      const actionSheet = page.locator('ion-action-sheet');
+
+      await actionSheet.evaluate((el: HTMLIonActionSheetElement) => el.present());
+      await ionActionSheetDidPresent.next();
+
+      await expect(actionSheet).toHaveScreenshot(screenshot(`action-sheet-scale`));
+    });
+  });
+});