add validation upload files and fix bug

src/index.scss

@@ -61,9 +61,9 @@
         display: flex;
         justify-content: center;
         align-items: center;
-        background-color: rgba(0, 0, 0, 0.9);
         text-align: center;
-        z-index: 10;
+        z-index: 1000;
+        background-color: rgba(0, 0, 0, 0.2);
 
         &-box{
             display: inline-block;