Problem with Images size and page resolution

I'm trying to code a little theme as a website for a club. I'm having the whole thing on tumblr since it's a platform that fully support html. I'm facing two problems that I hope someone can kindly help me with.

You can feel free view the whole thing and it source ( ctrl + u ) here : https://ad-astraz.tumblr.com/

While building it everything was going fine so far till I added pictures ( the planets and 3d things within the sections ) and as a result the pictures will change the website resoulation and add to it as showen in the picture here :

https://i.postimg.cc/05pGF9Ss/nkjk.png

And when for example viewed from my other laptop with smaller screen it become like this :

While it's supposed to be like this :

What would you recommend me to do in order to solve this problem and make the images and objects the same on all devices ?

Also how can I make the Page cut the pictures and ignore the extra space as in when changing the mode to fixed ? because I tried to make it align to right but then It will come into other objects/pictures so I prefer to keep it distance from other objects rather than the page.