fix: terminal, web, fonts (#12376)

Signed-off-by: fufesou <linlong1266@gmail.com>

flutter/lib/mobile/pages/terminal_page.dart

@@ -3,6 +3,7 @@ import 'package:flutter/services.dart';
 import 'package:flutter_hbb/common.dart';
 import 'package:flutter_hbb/models/model.dart';
 import 'package:flutter_hbb/models/terminal_model.dart';
+import 'package:google_fonts/google_fonts.dart';
 import 'package:xterm/xterm.dart';
 import '../../desktop/pages/terminal_connection_manager.dart';
 
@@ -31,6 +32,12 @@ class _TerminalPageState extends State<TerminalPage>
   late FFI _ffi;
   late TerminalModel _terminalModel;
 
+  // For web only.
+  // 'monospace' does not work on web, use Google Fonts, `??` is only for null safety.
+  final String _robotoMonoFontFamily = isWeb
+      ? (GoogleFonts.robotoMono().fontFamily ?? 'monospace')
+      : 'monospace';
+
   @override
   void initState() {
     super.initState();
@@ -81,6 +88,7 @@ class _TerminalPageState extends State<TerminalPage>
         _terminalModel.terminal,
         controller: _terminalModel.terminalController,
         autofocus: true,
+        textStyle: _getTerminalStyle(),
         backgroundOpacity: 0.7,
         padding: const EdgeInsets.symmetric(horizontal: 5.0, vertical: 2.0),
         onSecondaryTapDown: (details, offset) async {
@@ -101,6 +109,17 @@ class _TerminalPageState extends State<TerminalPage>
     );
   }
 
+  // https://github.com/TerminalStudio/xterm.dart/issues/42#issuecomment-877495472
+  // https://github.com/TerminalStudio/xterm.dart/issues/198#issuecomment-2526548458
+  TerminalStyle _getTerminalStyle() {
+    return isWeb
+        ? TerminalStyle(
+            fontFamily: _robotoMonoFontFamily,
+            fontSize: 14,
+          )
+        : const TerminalStyle();
+  }
+
   @override
   bool get wantKeepAlive => true;
 }