Increase banner padding/height on all pages + Modify Mobile Layout (York Template)

Site URL: https://www.hannahlee.cc/

Hi all! I'm currently redesign my portfolio and I cannot figure out how to increase the padding/height of my banner section on all of my pages. I want the banner to cover the entire height of the screen, and for the rest of the sections to only be visible when scrolling down. I would like the banner to cover the entire screen for all of my site pages. I've attached a screenshot as an example, where you can see the peeps of colour on the bottom from the other section. Would really appreciate the help! 

Additionally I have another problem with the mobile layout where the banner text overlaps the banner image. I have no idea how to solve this so any help at all would be greatly appreciated!