Huddle landing page using flexbox, margin manipulation and svg filters

This project is an important mini-milestone for me, as it's the last of the free level 1 projects for me to complete on this site. Given the experience on this and all the other such projects, I've gotten a lot more comfortable with HTML and CSS. The things I found challenging on this project were:

1. Styling the SVG images correctly without them disappearing
2. Correctly sizing the background image for every viewport.

Pretty satisfied with the solutions I came up with for both challenges however. Yet I continue to wonder about which images to add alt text onto. In this project, the .illustration image is the one in question for me. I opted not to add alt text to it as it strikes me as more decorative. Is this correct? Should it be styled anyway?