on click add css code example

Example 1: remove button highlight on click

.btn:focus {
  outline: none;
  box-shadow: none;
}

Example 2: how to add buttons in html

<button type="button" onclick="alert('You pressed the button!')">Click me!</button>

Example 3: how to css in jquery

$(init);
    
function init() {
    $("h1").css("backgroundColor", "yellow");
    $("#myParagraph").css({ "backgroundColor": "black", "color": "white" });
    $(".bordered").css("border", "1px solid black");
}