fix(button): use clamp for font sizes on circle shape (#29200)

core/src/components/button/button.ios.scss

@@ -149,19 +149,44 @@
 }
 
 ::slotted(ion-icon[slot="icon-only"]) {
-  font-size: 1.125em;
+  /**
+    * The values were provided through a native iOS app.
+    * min font size: 15px, default font size: 18px, max font size: 43px
+    *
+    * Since the `ion-button` uses `rem` for the font size, we can't
+    * just pass the desired icon font size in `em` to the `
+    * dynamic-font-clamp`. Instead, we need to adjust the base size 
+    * to account for the ion-button` font size.
+    *
+    * For example, if the default font size of `ion-button` is 16px
+    * (derived from rem), then the base size can use the default font
+    * size of the icon.
+    */
+  font-size: dynamic-font-clamp(0.84, 18px, 2.39, 1em);
 }
 
 :host(.button-small.button-has-icon-only) {
   // TODO(FW-6053): replace em value with the min-height variable.
   min-width: clamp(23px, 2.16em, 54px);
   // TODO(FW-6053): replace em value with the min-height variable.
   min-height: clamp(23px, 2.16em, 54px);
-
 }
 
 :host(.button-small) ::slotted(ion-icon[slot="icon-only"]) {
-  font-size: 1.4em;
+  /**
+    * The values were provided through a native iOS app.
+    * min font size: 12px, default font size: 17px, max font size: 40px
+    *
+    * Since the `ion-button` uses `rem` for the font size, we can't
+    * just pass the desired icon font size in `em` to the `
+    * dynamic-font-clamp`. Instead, we need to adjust the base size 
+    * to account for the ion-button` font size.
+    *
+    * For example, if the default font size of `ion-button` is 13px
+    * (derived from rem) and the default font size of the icon is
+    * 17px, then the base size would need to be increased.
+    */
+  font-size: dynamic-font-clamp(0.58, 20.93px, 1.92, 1em);
 }
 
 :host(.button-large.button-has-icon-only) {
@@ -172,7 +197,20 @@
 }
 
 :host(.button-large) ::slotted(ion-icon[slot="icon-only"]) {
-  font-size: 1em;
+  /**
+    * The values were provided through a native iOS app.
+    * min font size: 15px, default font size: 18px, max font size: 43px
+    *
+    * Since the `ion-button` uses `rem` for the font size, we can't
+    * just pass the desired icon font size in `em` to the `
+    * dynamic-font-clamp`. Instead, we need to adjust the base size 
+    * to account for the ion-button` font size.
+    *
+    * For example, if the default font size of `ion-button` is 20px
+    * (derived from rem) and the default font size of the icon is
+    * 18px, then the base size would need to be decreased.
+    */
+  font-size: dynamic-font-clamp(1.05, 14.4px, 2.99, 1em);
 }
 
 // iOS Button Focused

core/src/components/button/button.md.scss

@@ -142,7 +142,21 @@
 }
 
 ::slotted(ion-icon[slot="icon-only"]) {
-  font-size: 1.6em;
+  /**
+    * The values were provided through MD design,
+    * large and small are based on the iOS sizes.
+    * min font size: 15px, default font size: 22.4px, max font size: 43px
+    *
+    * Since the `ion-button` uses `rem` for the font size, we can't
+    * just pass the desired icon font size in `em` to the `
+    * dynamic-font-clamp`. Instead, we need to adjust the base size 
+    * to account for the ion-button` font size.
+    *
+    * For example, if the default font size of `ion-button` is 14px
+    * (derived from rem) and the default font size of the icon is
+    * 22.4px, then the base size would need to be increased.
+    */
+  font-size: dynamic-font-clamp(0.59, 25.6px, 1.68, 1em);
 }
 
 :host(.button-small.button-has-icon-only) {
@@ -153,7 +167,21 @@
 }
 
 :host(.button-small) ::slotted(ion-icon[slot="icon-only"]) {
-  font-size: 1.23em;
+  /**
+    * The values were provided through MD design,
+    * large and small are based on the iOS sizes.
+    * min font size: 12px, default font size: 16px, max font size: 40px
+    *
+    * Since the `ion-button` uses `rem` for the font size, we can't
+    * just pass the desired icon font size in `em` to the `
+    * dynamic-font-clamp`. Instead, we need to adjust the base size 
+    * to account for the ion-button` font size.
+    *
+    * For example, if the default font size of `ion-button` is 13px
+    * (derived from rem) and the default font size of the icon is
+    * 16px, then the base size would need to be increased.
+    */
+  font-size: dynamic-font-clamp(0.66, 19.7px, 2.05, 1em);
 }
 
 :host(.button-large.button-has-icon-only) {
@@ -164,7 +192,21 @@
 }
 
 :host(.button-large) ::slotted(ion-icon[slot="icon-only"]) {
-  font-size: 1.4em;
+  /**
+    * The values were provided through MD design,
+    * large and small are based on the iOS sizes.
+    * min font size: 15px, default font size: 28px, max font size: 43px
+    *
+    * Since the `ion-button` uses `rem` for the font size, we can't
+    * just pass the desired icon font size in `em` to the `
+    * dynamic-font-clamp`. Instead, we need to adjust the base size 
+    * to account for the ion-button` font size.
+    *
+    * For example, if the default font size of `ion-button` is 20px
+    * (derived from rem) and the default font size of the icon is
+    * 28px, then the base size would need to be increased.
+    */
+    font-size: dynamic-font-clamp(0.67, 22.4px, 1.92, 1em);
 }
 
 // Material Design Button: Hover