changing the font to open sans for typography in theme.ts, and making the toggled one bold

src/common/ButtonGroup.tsx

@@ -148,9 +148,9 @@ export default function ButtonGroup(props: Props){
           }}>
           {b.icon 
           ? 
-            b.icon 
+            b.icon
           : 
-            <Typography sx={{fontSize: textSize}}>
+            <Typography sx={{fontSize: textSize ?? 13, fontWeight: checkToggled(i) ? 650 : 500}}>
               {b.title}
             </Typography>
           }

src/theme/theme.ts

@@ -17,6 +17,20 @@ const baseTheme: ThemeOptions = {
       paper: '#f5f5f5',
     },
   },
+  typography: {
+    fontFamily: [
+      "Open Sans",
+      "-apple-system",
+      "BlinkMacSystemFont",
+      '"Segoe UI"',
+      '"Helvetica Neue"',
+      "Arial",
+      "sans-serif",
+      '"Apple Color Emoji"',
+      '"Segoe UI Emoji"',
+      '"Segoe UI Symbol"'
+    ].join(",")
+  }
   // Add other options if needed
 };