added i18next language lib and some style fixes

src/components/ui/FullscreenButton/FullscreenButton.tsx

@@ -3,43 +3,40 @@ import { Button } from "../button/button";
 import fullscreen from "../../../images/icons/fullscreen.svg";
 import fullscreenOff from "../../../images/icons/fullscreenOff.svg";
 
-
-export const FullscreenButton = ({ }) => {
+export const FullscreenButton = ({}) => {
   const [active, setActive] = useState(false);
   const [button, setButton] = useState({
     icon: fullscreen,
-    active: "Развернуть",
-    inactive: "Свернуть",
+    inactive: "fullscreen-control-btn",
+    active: "fullscreen-control-btn-active",
     type: "fullscreen",
-
-  })
+  });
 
   function handleClick() {
     setActive((prev) => !prev);
     setButton({
       icon: active ? fullscreen : fullscreenOff,
-      active: "Развернуть",
-      inactive: "Свернуть",
+      inactive: "fullscreen-control-btn",
+      active: "fullscreen-control-btn-active",
       type: "fullscreen",
-    })
+    });
 
     if (active) {
-      document.exitFullscreen()
+      document.exitFullscreen();
     } else {
-      document.body.requestFullscreen()
+      document.body.requestFullscreen();
     }
   }
 
-
   useEffect(() => {
     return () => {
-      document.exitFullscreen()
-    }
-  }, [])
+      document.exitFullscreen();
+    };
+  }, []);
 
   return (
     <div className="toolbar-button-area">
       <Button button={button} active={active} onClick={handleClick}></Button>
     </div>
   );
-};
+};