Add screenshare button styling

src/RoomButton.jsx

@@ -9,6 +9,7 @@ import { ReactComponent as HangupIcon } from "./icons/Hangup.svg";
 import { ReactComponent as SettingsIcon } from "./icons/Settings.svg";
 import { ReactComponent as GridIcon } from "./icons/Grid.svg";
 import { ReactComponent as SpeakerIcon } from "./icons/Speaker.svg";
+import { ReactComponent as ScreenshareIcon } from "./icons/Screenshare.svg";
 
 export function RoomButton({ on, className, children, ...rest }) {
   return (
@@ -37,6 +38,18 @@ export function VideoButton({ enabled, ...rest }) {
   );
 }
 
+export function ScreenshareButton({ enabled, className, ...rest }) {
+  return (
+    <RoomButton
+      className={classNames(styles.screenshareButton, className)}
+      {...rest}
+      on={enabled}
+    >
+      <ScreenshareIcon />
+    </RoomButton>
+  );
+}
+
 export function HangupButton({ className, ...rest }) {
   return (
     <RoomButton