change css with vanilla javascript code example

Example 1: how to give css style in javascript

document.getElementById("myH1").style.color = "red";

Example 2: adding styling to element using javascript

var elem = document.querySelector('#some-element');

// Set color to purple
elem.style.color = 'purple';

// Set the background color to a light gray
elem.style.backgroundColor = '#e5e5e5';

// Set the height to 150px
elem.style.height = '150px';