Add scalable font size support for buttons and split buttons based on size

packages/button_m3e/lib/src/button_m3e.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:m3e_design/m3e_design.dart';
 
 import 'button_tokens_adapter.dart';
 import 'enums.dart';
@@ -130,7 +131,21 @@ class _ButtonM3EState extends State<ButtonM3E> {
   }
 
   Widget _buildContent(ButtonMeasurements m) {
-    final text = DefaultTextStyle.merge(child: widget.label);
+    final m3e = context.m3e;
+    final bfs = m3e.typography.buttonFontSize;
+    final double? fontSize = switch (widget.size) {
+      ButtonM3ESize.xs => bfs.xs,
+      ButtonM3ESize.sm => bfs.sm,
+      ButtonM3ESize.md => bfs.md,
+      ButtonM3ESize.lg => bfs.lg,
+      ButtonM3ESize.xl => bfs.xl,
+    };
+
+    final text = DefaultTextStyle.merge(
+      style: fontSize == null ? null : TextStyle(fontSize: fontSize),
+      child: widget.label,
+    );
+
     if (widget.icon == null) return text;
     return Row(
       mainAxisSize: MainAxisSize.min,

packages/m3e_design/lib/tokens/typography_tokens.dart

@@ -128,3 +128,24 @@ class M3ETypography {
     );
   }
 }
+
+@immutable
+class ButtonFontSize {
+  final double xs;
+  final double sm;
+  final double md;
+  final double lg;
+  final double xl;
+
+  const ButtonFontSize({
+    this.xs = 14,
+    this.sm = 14,
+    this.md = 16,
+    this.lg = 20,
+    this.xl = 24,
+  });
+}
+
+extension M3EButtonFontSizeExt on M3ETypography {
+  ButtonFontSize get buttonFontSize => const ButtonFontSize();
+}

packages/split_button_m3e/lib/src/split_button.dart

@@ -479,6 +479,16 @@ class _LeadingContent extends StatelessWidget {
     final iconBlock = size.leadingIconBlockWidth;
     final gap = size.gapIconToLabel;
 
+    // Scale label font-size with button size (xs/s unchanged).
+    final bfs = m3e.typography.buttonFontSize;
+    final double? labelFontSize = switch (size) {
+      SplitButtonM3ESize.xs => bfs.xs,
+      SplitButtonM3ESize.sm => bfs.sm,
+      SplitButtonM3ESize.md => bfs.md,
+      SplitButtonM3ESize.lg => bfs.lg,
+      SplitButtonM3ESize.xl => bfs.xl,
+    };
+
     Widget content;
     if (icon != null && (label?.isNotEmpty ?? false)) {
       content = Padding(
@@ -497,7 +507,10 @@ class _LeadingContent extends StatelessWidget {
               child: Text(
                 label!,
                 overflow: TextOverflow.ellipsis,
-                style: m3e.typography.base.labelLarge?.copyWith(color: color),
+                style: m3e.typography.base.labelLarge?.copyWith(
+                  color: color,
+                  fontSize: labelFontSize,
+                ),
               ),
             ),
           ],
@@ -519,7 +532,9 @@ class _LeadingContent extends StatelessWidget {
         child: Text(
           label ?? '',
           overflow: TextOverflow.ellipsis,
-          style: DefaultTextStyle.of(context).style.copyWith(color: color),
+          style: DefaultTextStyle.of(
+            context,
+          ).style.copyWith(color: color, fontSize: labelFontSize),
         ),
       );
     }