Not able to set a section of a webpage to full viewport height[CLOSED][FIXED]

I’ve thoroughly checked multiple times and tweaked the code a few times. Everything else works but still I am not able to set the section with the id of “welcome-section” to full viewport height. All help and responses are appreciated : )

Here is the link to the code:
https://codepen.io/x-spec/pen/XWjeLWQ

Cut all the css from the html section and paste in in css section. Your work will be done. Check your code pen now

Code Pen

Thank you so much for the help! It’s fixed now.