Fix fonts definitions

Author: aMarcireau

ui/src/styles.css

@@ -1,26 +1,26 @@
 @font-face {
-    font-family: "Roboto", sans-serif;
+    font-family: "Roboto";
     font-style: normal;
     font-weight: 400;
     src: url("../fonts/Roboto-Regular.woff2") format("woff2");
 }
 
 @font-face {
-    font-family: "Roboto", sans-serif;
+    font-family: "Roboto";
     font-style: normal;
     font-weight: 700;
     src: url("../fonts/Roboto-Bold.woff2") format("woff2");
 }
 
 @font-face {
-    font-family: "Roboto", sans-serif;
+    font-family: "Roboto";
     font-style: italic;
     font-weight: 400;
     src: url("../fonts/Roboto-Italic.woff2") format("woff2");
 }
 
 @font-face {
-    font-family: "RobotoMono", monospace;
+    font-family: "RobotoMono";
     font-style: normal;
     font-weight: 400;
     src: url("../fonts/RobotoMono-Regular.woff2") format("woff2");