:root {
  --bg-center: #124e8a;
  --bg-edge: #11365c;
  --star-white: #f7f8fa;
  --planet-size: min(52vw, 56vh, 560px);
  --planet-rest-top: 32%;
}

body.intro-active {
  overflow: hidden;
  background: var(--bg-edge);
  color: var(--star-white);
}

body.intro-active #app {
  min-height: 100dvh;
}

.stage {
  width: 100%;
  height: 100dvh;
  position: relative;
  overflow: hidden;
  background: radial-gradient(circle at center, var(--bg-center), var(--bg-edge));
  font-family: "Swei Gothic CJK TC", "Noto Sans TC", "Microsoft JhengHei",
    sans-serif;
}

.stars {
  position: absolute;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
  transform-origin: center center;
}

.star {
  position: absolute;
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

.star-far {
  background: #b3b3b3;
  filter: blur(0.7px);
  opacity: 0.72;
}

.star-near {
  background: #ffffff;
}

.stage.is-zoom .stars-far {
  transform: scale(1.1);
  transition: transform 1s ease-out;
}

.stage.is-zoom .stars-near {
  transform: scale(1.24);
  transition: transform 1s ease-out;
}

.stage .hero,
.stage .login-panel {
  position: relative;
  z-index: 1;
  height: 100%;
}

.stage .planet {
  position: absolute;
  left: 50%;
  top: var(--planet-rest-top);
  width: var(--planet-size);
  height: auto;
  display: block;
  transform: translate(-50%, -50%);
  transform-origin: center center;
}

.stage .brand {
  position: absolute;
  left: 50%;
  top: calc(var(--planet-rest-top) + (var(--planet-size) * 0.46));
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
  margin-bottom: 0;
  transform: translateX(-50%);
}

.stage .logo {
  width: min(52vw, 500px);
  height: 72px;
  display: block;
  object-fit: cover;
  object-position: 50% 47.5%;
}

.stage .logo-small {
  width: min(60vw, 480px);
  height: 80px;
  margin-top: 0;
}

.stage .tagline {
  margin: 2px 0 0;
  font-size: 26px;
  letter-spacing: 0.55em;
  text-indent: 0.55em;
  font-weight: 400;
  color: var(--star-white);
}

.stage .login-btn {
  margin-top: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 188px;
  height: 52px;
  padding: 0 40px;
  border: 1.5px solid rgba(247, 248, 250, 0.88);
  border-radius: 999px;
  color: var(--star-white);
  text-decoration: none;
  font-size: 22px;
  letter-spacing: 0.45em;
  text-indent: 0.45em;
  background: transparent;
  cursor: pointer;
  font-family: inherit;
  transition: background 0.2s ease, transform 0.2s ease;
}

.stage .login-btn:hover,
.stage .login-btn:focus-visible {
  background: rgba(247, 248, 250, 0.12);
  outline: none;
}

.stage .login-btn:active {
  transform: scale(0.98);
}

.stage .brand .login-btn {
  margin-top: 32px;
}

.stage .login-panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 0 64px 40px;
  text-align: center;
}

.stage .intro-veil {
  position: absolute;
  inset: 0;
  z-index: 4;
  background: #000;
  opacity: 1;
  pointer-events: none;
  transition: opacity 1s ease;
}

.stage .intro-veil.is-clear {
  opacity: 0;
}

.stage.is-intro .hero .planet {
  top: 50%;
  transform: translate(-50%, -50%) scale(0.5);
}

.stage.is-intro.is-zoom .hero .planet {
  top: var(--planet-rest-top);
  transform: translate(-50%, -50%) scale(1);
  transition: transform 1s ease-out, top 1s ease-out;
}

.stage.is-intro .brand {
  opacity: 0;
}

.stage.is-intro.is-ready .brand {
  opacity: 1;
  transition: opacity 0.7s ease;
}

@media (prefers-reduced-motion: reduce) {
  .stage .intro-veil {
    display: none;
  }

  .stage.is-intro .hero .planet,
  .stage.is-intro.is-zoom .hero .planet {
    top: var(--planet-rest-top);
    transform: translate(-50%, -50%) scale(1);
    transition: none;
  }

  .stage.is-zoom .stars-far,
  .stage.is-zoom .stars-near {
    transform: none;
    transition: none;
  }

  .stage.is-intro .brand,
  .stage.is-intro.is-ready .brand {
    opacity: 1;
    transition: none;
  }
}