/* (A) FULL SCREEN WRAPPER */
#spinner {
    position: fixed;
    top: 0; left: 0;
    width: 100vw; height: 100vh;
    z-index: 9999;
    background: rgba(0, 0, 0, 0.7);
    transition: opacity 0.2s;
  }

  /* (B) CENTER LOADING SPINNER */
  #spinner img {
    position: absolute;
    top: 50%; left: 50%;
    transform: translate(-50%);
  }
  #spinner h5 {
    position: absolute;
    top: 56%; left: 50%;
    transform: translate(-50%);
    text-align: center;
  }
  /* (C) SHOW & HIDE */
  #spinner {
    visibility: hidden;
    opacity: 0;
  }
  #spinner.show-spinner {
    visibility: visible;
    opacity: 1;
  }

  /* (X) DOES NOT QUITE MATTER */
  html, body {
    margin: 0;
    padding: 0;
  }