background color

1body {
2  background-color: green;
3}

1body {
2  background-color: rgb(255,255,255);
3}

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

1div {
2 opacity:25% ; 
3}

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

1    document.getElementById('id').style.backgroundColor = 'green' ;