demo 2

HTML<button>Press Me!</button>

CSSbutton {
  width:20px;
  height:28px;
  color:#fff;
  font-size:28px;
  padding:11px 15px;
  border-radius:5px;
  background:#14ADE5;
}

JS<button onclick="myFunction()">Post</button>

<script>
function myFunction() {
    document.write(5 + 6);
}
</script>

Jquery$(document).ready(function{
 jQuery.cssRule(".post", "display", "block");
});