Aad thus CSS ID in html with border and animation.

Question

Use this

#intro {
color: white;
background-color: gray;
}

Answer 1

For borders:
https://www.w3schools.com/css/css_border.asp

For animations:
https://www.w3schools.com/css/css3_animations.asp

For web development general:
https://www.w3schools.com/