css coor background

1html,body {
2  background-color: red;
3}

1div {
2 opacity:25% ; 
3}

1body{
2  background: lightblue;
3}

1<style>
2body {
3  background-color: coral;
4}
5</style>

1body {background-color: coral;}
2

1//javascript type css:
2document.body.style.backgroundColor = "blue";
3// or inline css:
4<div style="background-color: blue;"></div>