fixed new method for grid drawing

_src/assets/ts/snake.ts

@@ -19,7 +19,7 @@ function drawField(){
     let fieldHTML:string = "";
     for(let i:number = 1; i <= fieldSize; i++){
         for(let x:number = 1; x <= fieldSize; x++){
-            let elementClass:string = "";
+            let elementClass:string = "grid";
             for(let y:number = 0; y<snake.length; y++){
                 let currentSnake = snake[y];
                 if(currentSnake[0] == i && currentSnake[1] == x){