tweak background size

public/sass/pages/_login.scss

@@ -9,7 +9,7 @@
   align-items: center;
   justify-content: center;
   background-image: url(../img/heatmap_bg_test.svg);
-  background-size: 100%;
+  background-size: cover;
 }
 
 input:-webkit-autofill,