Update _variables.scss and replace Roboto with system fonts

resources/assets/sass/_variables.scss

@@ -3,6 +3,6 @@
 $body-bg: #f5f8fa;
 
 // Typography
-$font-family-sans-serif: "Roboto", sans-serif;
+$font-family-sans-serif:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
 $font-size-base: 0.9rem;
 $line-height-base: 1.6;