JSFiddle - React, Tailwind, and code Playground

HTML

<div id="login_modal_wrapper">
  <div id="ajax_spinner">
    loading icon
  </div>
  <div id="login_modal"></div>
</div>

CSS

#login_modal_wrapper {
  background: #eee;
  background: red;/*rgba(0,0,0,0.7);*/
  width: 100%; height: 100%;
  position: fixed; top: 0; left: 0;
  z-index: 10003;
}
#ajax_spinner {
  width: 34px;
  height: 34px;
  position: fixed;
  top: 50%;
  left: 50%;
  margin-left: -17px;
  margin-top: -17px;
  z-index: 200000;
}
#login_modal {
  z-index: 10002;
  background: #eee;
  border: 2px solid #092834;
  border: 2px solid rgba(9,40,52,0.6);
  border-radius: 20px;
  width: 700px;
  height: 240px;
  position: fixed;
  top: 50%;
  left: 50%;
  margin-left: -350px;
  margin-top: -120px;
}