main {
  display: flex;
  flex-flow: row;
  justify-content: center;
  width: 100%;
  padding: 0 16px;
  margin-top: 20px;
  padding: 44px 16px;
}

header {
  background-image: var(--asset-header-bg);
  padding: 20px 5px 80px;
}

.IntroShellImg {
  width: 350px;
  height: 500px;
  padding: 10px 0;
  margin-right: 32px;
}

.IntroShellImg img {
  display: block;
  width: 350px;
  height: 400px;
  background-color: aqua;
}

.TestIntroShell .IntroShellTextBox h2 {
  margin-bottom: 8px;
}

.TestIntroShell .IntroShellTextBox .Creator {
  display: flex;
  flex-flow: row;
  padding: 10px 0 18px;
}

.TestIntroShell .IntroShellTextBox .Creator img {
  display: block;
  border-radius: 24px;
  width: 24px;
  height: 24px;
  margin-right: 8px;
}

.TestIntroShell .IntroShellTextBox .Creator .CreatorName {
  font-size: 0.95rem;
  font-weight: 600;
}

.TestIntroShell .IntroShellTextBox .IntroDescription {
  font-size: 0.85rem;
}

.IntroBtnShell {
  display: flex;
  flex-flow: row;
  margin-top: 16px;
}

.IntroBtnShell > div > button {
  background-color: transparent;
  transition: all 0.5 ease-in-out;
}

.IntroBtnShell > div > button:hover {
  transform: scale(1.05);
}

.IntroBtnShell .TestStart {
  margin-right: 16px;
}

.IntroBtnShell .TestStart > button {
  width: 146px;
}

.IntroBtnShell .TestShare > button {
  width: 146px;
}

footer {
  position: static;
  width: 1230px;
}

/* ---------- Preload overlay (intro -> quiz) ---------- */
.preload-overlay {
  position: fixed;
  inset: 0;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(4px);
  z-index: 9999;
  display: none;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity 0.2s ease;
}

.preload-overlay.active {
  display: flex;
  opacity: 1;
}

.preload-skeleton {
  width: min(420px, 92vw);
  padding: 22px;
  text-align: center;
}

.skeleton-image {
  width: 320px;
  height: 320px;
  max-width: 80vw;
  max-height: 80vw;
  margin: 0 auto 18px;
  border-radius: 14px;
  background: linear-gradient(90deg, #f1f1f1 25%, #e6e6e6 50%, #f1f1f1 75%);
  background-size: 200% 100%;
  animation: skeleton-shimmer 1.35s infinite;
}

.skeleton-progress {
  width: 100%;
  height: 10px;
  border-radius: 999px;
  background: #e7e7e7;
  overflow: hidden;
  margin: 0 auto 12px;
}

.skeleton-progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #ffd48d, #ffc400);
  transition: width 0.2s ease;
}

.skeleton-text {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 700;
  color: #333;
}

@keyframes skeleton-shimmer {
  0% {
    background-position: -200% 0;
  }

  100% {
    background-position: 200% 0;
  }
}

/* Mobile (<=900px) */
@media (max-width: 900px) {
  body {
    display: block;
  }

  .PageShell {
    width: 100%;
    /* Sticky footer pattern: fill viewport, push footer to bottom when content is short */
    min-height: 100vh;
  }

  header {
    padding: 28px 12px 20px;
    background-image: var(--asset-header-bg-non);
    background-size: 100% auto;
    background-repeat: no-repeat;
    background-position: top center;
  }

  .fixed-header {
    width: 100%;
    max-width: none;
    left: 0;
    transform: none;
  }

  .bg-on {
    background-size: 100% auto;
    background-repeat: no-repeat;
    background-position: top center;
  }

  header .Head {
    padding: 0;
    align-items: center;
  }

  header .Head .Logo {
    width: 22%;
    min-width: 120px;
  }

  header .Head .Logo a img {
    width: 100%;
    max-width: 160px;
  }

  main {
    flex-flow: column;
    align-items: center;
    padding: 0 12px 20px;
    margin-top: 0;
  }

  .IntroShellImg {
    width: 100%;
    height: auto;
    margin-right: 0;
  }

  .IntroShellImg img {
    width: 100%;
    height: auto;
  }

  .IntroBtnShell {
    flex-flow: row;
    justify-content: space-between;
    gap: 12px;
    width: 100%;
    margin-top: 30px;
  }

  .IntroBtnShell .TestStart,
  .IntroBtnShell .TestShare {
    margin-right: 0;
    width: 50%;
  }

  .IntroBtnShell button {
    width: 100%;
  }

  footer {
    position: static;
    width: 100%;
  }
}