Intro with dropdown nav

What did you find difficult while building the project? Had issues changing the image based on the screen size, loaded image based on measuring the width of the screen, wrote a JS function to detect the screen width and load the image, however the function was called onload, when resizing the screen width is not measured, hence used the hero image as background image.

What did you find difficult while building the project? Yes, any tip on layout would be good. I started with mobile first design.