Answers for "apply multiple css using javacsript to all class"

how to add multiple css style in javascript

document.getElementById("myElement").style.cssText = "display: block; position: absolute";

//use template literals
document.getElementById("myElement").style.cssText = `
  display: block; 
  position: absolute;
`;

css assign multiple classes to one element

To specify multiple classes, separate the class names with a space,
e.g. <span class="classA classB">.
This allows you to combine several CSS classes for one HTML element.