style.css

html,
body {
  width: 100%; height: 100%; margin: 0;
  background: #fff;
  display: flex;
  align-items: center;
}

@media (max-width: 420px) {
  body {
    padding-top: 62px;
  }
}

.loader {
  background-image: url("loader.svg");
  background-size: contain;
  display: none;
  height: 48px;
  width: 48px;
  position: absolute;
  left: 47%;
  margin: 0 auto;
}
.loader.is-loading {
  display: block;
  animation: loader infinite 0.5s;
}
@keyframes loader {
  0% {
    transform: scale(1);
  }
  50% {
    transform: scale(.90);
  }
  100% {
    transform: scale(1);
  }
}

webview {
  width: 100%;
  height: 100%;
  z-index: 1;
}

.title-bar {
  -webkit-app-region: drag;
  position: absolute;
  display: block;
  height: 34px;
  width: 100%;
  top: 0;
  z-index: 999999;
  background: #fff;
  opacity: 0.8;
}