.preview-main {
  max-width: 980px;
  margin: 2rem auto 3rem;
  font-size: 1.06rem;
  line-height: 1.8;
}

.preview-main a {
  text-decoration: none;
}

.preview-hero {
  margin-bottom: 1.8rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid #d8d8d8;
}

.preview-kicker {
  margin: 0;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.78rem;
  opacity: 0.75;
}

.preview-main h1 {
  margin: 0.4rem 0 0.6rem;
  font-size: 2rem;
  line-height: 1.2;
}

.preview-main h2 {
  margin: 0 0 0.7rem;
}

.preview-list,
.cards-grid {
  list-style: none;
  margin: 0;
  padding: 0;
}

.preview-list li {
  margin: 0 0 1.3rem;
  padding: 1.1rem 0 1.2rem;
  border-bottom: 1px solid #e7e7e7;
}

.preview-list h3 {
  margin: 0 0 0.35rem;
}

.preview-list p {
  margin: 0.45rem 0 0;
}

.readable-shell article {
  background: #f8fafc;
  border: 1px solid #ebeff5;
  border-radius: 12px;
  padding: 1.1rem 1.2rem;
  margin-bottom: 1.2rem;
}

.readable-shell blockquote {
  margin: 0.8rem 0 0;
  padding-left: 0.9rem;
  border-left: 3px solid #778ca3;
}

.preview-cards {
  max-width: 1100px;
}

.cards-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.post-card {
  border: 1px solid #e4e7eb;
  border-radius: 14px;
  padding: 1rem 1rem 0.9rem;
  background: #ffffff;
  transition: transform 180ms ease, box-shadow 180ms ease;
}

.post-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 24px rgba(10, 20, 30, 0.08);
}

.post-card h2 {
  margin: 0 0 0.45rem;
  font-size: 1.2rem;
}

.post-card p {
  margin: 0.45rem 0 0.9rem;
}

.read-more {
  display: inline-block;
  font-size: 0.92rem;
  font-weight: 600;
}

.preview-immersive {
  max-width: 1120px;
}

.progress-demo {
  position: sticky;
  top: 0;
  z-index: 2;
  height: 6px;
  margin-bottom: 1rem;
  background: #e6e9ef;
  border-radius: 999px;
}

.progress-demo span {
  display: block;
  width: 62%;
  height: 100%;
  background: linear-gradient(90deg, #1f8dd6, #3ac2a5);
  border-radius: 999px;
}

.immersive-layout {
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr);
  gap: 1.4rem;
}

.toc-demo {
  position: sticky;
  top: 1.2rem;
  align-self: start;
  border: 1px solid #e4e7eb;
  border-radius: 12px;
  padding: 0.9rem 1rem;
  background: #fff;
}

.toc-demo h3 {
  margin: 0 0 0.45rem;
}

.toc-demo ul {
  margin: 0;
  padding-left: 1rem;
}

.immersive-content article {
  margin-bottom: 1rem;
  border: 1px solid #e7ebf1;
  border-radius: 12px;
  padding: 1rem 1.1rem;
  background: #fff;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.6rem;
}

.related-grid a {
  display: block;
  border: 1px dashed #b7c2cf;
  border-radius: 10px;
  padding: 0.7rem;
  background: #f8fbff;
}

@media (max-width: 900px) {
  .cards-grid {
    grid-template-columns: 1fr;
  }

  .immersive-layout {
    grid-template-columns: 1fr;
  }

  .toc-demo {
    position: static;
  }

  .related-grid {
    grid-template-columns: 1fr;
  }
}