Base_Apparel_coming_soon_page

Hello, everyone! Please, could somebody answer me, what should I use inside the <button> instead of <embed> to show svg-image? Why <svg> doesn't work? As far as you will see, I also set autocomplete of the input to "off", that is because I did not understand how to style the, let it be, "invalid state" of this form . For example, those error-messages "email should contain "@"", which my browser shows with yellow exclamation mark(I have Google Chrome) or a list of my valid emails. So, I would like to style these messages and windows, but don't know how. I would truely appreciate your reply and some other comments!