Update app.py

app.py

@@ -15,7 +15,7 @@ def set_bg_hack(main_bg):
              background: url(data:image/{main_bg_ext};base64,{base64.b64encode(open(main_bg, "rb").read()).decode()});
              background-repeat: no-repeat;
              background-position: right 50% bottom 95% ;
-             background-size: contain;
+             background-size: cover;
              background-attachment: scroll;
          }}
          </style>