Newsletter sign-up form using flexbox

Some challenges I came across involved finding out how to validate the email address. Some research on stack overflow helped me come across a handy regular expression to take care of this.

Another challenge came when I tried to change the background of the input box to a reddish hue. Interestingly, using .style.backgroundColor made it so the color only flashed for a moment but using .style.background seemed to work as intended. I'm not sure why.