Background is not responsive for mobile or fullscreen

Store Design
1

My background photo looks fine when on desktop mode but when in fullscreen the bottom half gets cut out and for mobile the picture is cut out vertically

2

Hi the store link is a689bc-f9.myshopify.com and the password newstoyearly

3

Hi @wpr12 ,

Please send me the code of theme.liquid file, I will check and guide it

4

Hi I private messaged you

5

Hi @wpr12 ,

Please add code:

#MainContent {
          background-image: url(//a689bc-f9.myshopify.com/cdn/shop/files/Homepage5.png?v=1723341306);
          background-size: cover;
          background-repeat: no-repeat;
          background-position: center;
        }