There’s great artistry and fun in your design!
UX wise, your current about section reads and is formatted more-so like a header, and the about button only dropping someone down a few pixels when they click it from start is a bit odd. I’d consider creating a second about section below it and just calling the current section a sweet header
UI wise, when viewing the projects there’s a large gap of space next to each image. Consider floating the image to one side or the other so that the text wraps around it to fill the void there, or maybe center the image inside the container. Might also want to add a way to include your projects title names.
As for your stacking/breaking div gallery issue, my preferred solution is to first set the width of the gallery container, then base the total width of your gallery items to less than 50% of that width (which should factor in the gallery container padding, as well as the gallery item’s padding, margin, and border width), and then set them to display inline-block. If you use a percentage value for the width then the contents of each gallery item can then be set to be centered within the div and will remain centered as the screen width changes. In this instance, I recommend also including a min-width value that is a set value (non-percentage) in order to have them stack up instead of squishing beyond readability on really small screens. If you want them to stay uniform vertically as well, you’ll have to set the gallery item height to set value. As a last note it’s generally best in all of these instances to use margins over padding,.