.shu-dir-bkg-env {
  position: absolute; top: 0; left: 0; right: 0; bottom: 0; z-index: -1; pointer-events: none;
}

.shu-dir-bkg {
  position: sticky;
  top: 0; left:0;
  width: 100%;
  max-height: 100%;
  background-position: top right;
  background-repeat: no-repeat;
}

/* 小螢幕 */
@media (max-width:640px) {
  .shu-dir-bkg { 
    height: 100vh;
    background-size: auto 100vh; 
    background-position: right -4em top 0 !important;
  }
}

/* 中螢幕 */
@media (max-width:1000px) and (min-width:640.1px) {
  .shu-dir-bkg {
    height: 100vh;
    background-size: auto 100vh;
    background-position: right -3em top 0 !important;
  }
}

/* 大螢幕 */
@media (max-width:1360px) and (min-width:1000.1px) {
  .shu-dir-bkg { 
    height: 120vh;
    background-size: auto 120vh;
  }
}

/* 巨螢幕 */
@media (min-width:1360.1px) {
  .shu-dir-bkg {
    height: 140vh;
    background-size: auto 140vh;
  }
}