well i try only css pure, only with i know :)

There is no need for the section tag in the html, give each article a class name for the styling To center a content on a page, add min-height:100vh; display:flex; align-items-center: justify-content: center; to the body. you forgot to add the background-image to the body, give the background-image , a background-size:contain; background-repeat: no-repeat. There no need for display flex and it properties in the main and .caja, give the main a width value , bont giver it a height value. Give the second article a background color of white and a padding value. Hope am helpful HAPPY CODING

i dont know what happen because on netlify its ok, see https://joyful-bublanina-8c23c1.netlify.app/

so many errors, well i need fix it and send again TT