JSFiddle - React, Tailwind, and code Playground

HTML

<button onclick="setActionAndSubmit('id_form_workitem_create', 'create');" tooltip-title="please fill all mandatory fields">Create</button>

CSS

button[tooltip-title]:hover:before {
  content: attr(tooltip-title);
  padding: 2px 2px;
  color: #333;
  position: absolute;
  left: 40px;
   top: 40px; 
  z-index: 20;
  white-space: nowrap;
  -moz-border-radius: 2px;
  -webkit-border-radius: 2px;
  border-radius: 2px;
  -moz-box-shadow: 0px 0px 4px #222;
  -webkit-box-shadow: 0px 0px 4px #222;
  box-shadow: 0px 0px 4px #222;
  background-image: -moz-linear-gradient(top, #eeeeee, #cccccc);
  background-image: -webkit-gradient(linear,left top,left bottom,color-stop(0, #eeeeee),color-stop(1, #cccccc));
  background-image: -webkit-linear-gradient(top, #eeeeee, #cccccc);
  background-image: -moz-linear-gradient(top, #eeeeee, #cccccc);
  background-image: -ms-linear-gradient(top, #eeeeee, #cccccc);
  background-image: -o-linear-gradient(top, #eeeeee, #cccccc);
}