Is it valid to use html
html {
border: solid 10px #000;
background-color: #EE3E4E;
}
instead of body
body {
border: solid 10px #000;
background-color: #EE3E4E;
}
in CSS?
Absolutely you can, its just should you is the main question, but again thats all convention. Most prefer to set defaults in the body tag, so another stylist touching your site may expect defaults there. Of course just an inspection tool will show them where the defaults are. So Yep, but convention usually dictates body would be your "default" style pane
Yes, you can. It will just change everything in between. Almost all of the tags can be used in CSS