NFT Landing Page Project using HTML and CSS

Please help me out with my queries!! 1)How should we change the size of NFT card in such a way that it adapts to the screen size. Like in my case it has fixed pixels size but I wanted it in percentage of the page. (I tried many things like align-center, margin: auto but couldn't achieve it) 2) A follow-up to (1) how to implement website design that will work on both desktop and mobile browsers. 3)If there are multiple cards, then how to align the image with respect to the card. ( I tried position : relative but I couldn't do it). In short how can we align elements to a particular block?