Mobile first using SasS and BEM with flexbox and grid

Greetings All 🖐🏼,

Any feedback on anything is greatly appreciated.

Things I would like to know ,

How do I change color of arrow img on hover in see how it works link? How can I add that error message "please enter the valid email address" in cta section? In footer, I have used flexbox for desktop and when trying to shrink window, all the div/items gets bunched up rather going to next line at the bottom. I tried with flex-wrap:wrap but it doesn't work. Any idea or suggestion how to make them divs in footer go to next line in bottom using flexbox?

Best regards, KT