Done! .... sort of...Portfolio project review please

I’ve submitted this as ‘complete’, but I still have a couple of questions.

1- I wanted the ‘welcome’ text in the first panel to actually float in the dark area of the image (lower right) but I could not figure out how to anchor it there without inputting actual pixels which would be wrong as soon as the size adjusted.
2 - my portfolio thumbnails are not the same size. The internet searching i have found simply said to use bootstrap 4, which promptly broke my nav bar. Any ideas on uniformity at all sizes?
3 - the social media buttons are hard coded to a specific px size width and run into the headshot image when the screen is reduced. help?