use nicer fonts for image generation

index.html

@@ -157,13 +157,13 @@
       const LOGO_WIDTH_AND_HEIGHT = 175;
       const IMAGE_PLACEHOLDER = "./img/logo_g.png"
 
-      const TITLE_FONT = "45px serif";
+      const TITLE_FONT = "45px -apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen-Sans,Ubuntu,Cantarell,'Helvetica Neue',sans-serif";
 
-      const INFOS_FONT = "30px serif";
+      const INFOS_FONT = "30px -apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen-Sans,Ubuntu,Cantarell,'Helvetica Neue',sans-serif";
       const INFOS_START_POSITION = 150;
       const INFOS_LINE_BREAK = 50;
 
-      const PUBKEY_FONT = "20px serif";
+      const PUBKEY_FONT = "20px -apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen-Sans,Ubuntu,Cantarell,'Helvetica Neue',sans-serif";
 
       const G1_WRONG_SYMBOL = "G1";
       const G1_SYMBOL = "Ğ1";