.hub-shell {
  width: min(1180px, 94vw);
  margin: 0 auto;
  padding: 28px 0 56px;
}

.hub-hero {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 2rem;
  padding: clamp(28px, 5vw, 58px);
  border: 1px solid var(--line);
  border-radius: 34px;
  background:
    linear-gradient(120deg, rgba(94, 124, 255, 0.2), transparent 52%),
    var(--card);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.hub-hero h1 {
  max-width: 700px;
  margin: 0.25rem 0 0.7rem;
  font-size: clamp(2.4rem, 6vw, 5.2rem);
  line-height: 0.98;
  letter-spacing: -0.055em;
}

.hub-hero > div > p:last-child { max-width: 650px; margin: 0; color: var(--muted); font-size: 1.05rem; }
.hub-language { flex: 0 0 auto; }

.hub-summary {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 16px 0 38px;
}

.hub-summary > div {
  min-height: 96px;
  display: grid;
  align-content: center;
  gap: 0.28rem;
  padding: 18px 22px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--card);
}

.hub-summary span { color: var(--muted); font-size: 0.8rem; }
.hub-summary strong { font-size: clamp(1.15rem, 2.2vw, 1.7rem); }

.hub-section-heading {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 2rem;
  margin-bottom: 18px;
}

.hub-section-heading h2 { margin: 0.15rem 0 0; font-size: 2rem; }
.hub-section-heading > p { max-width: 560px; margin: 0; color: var(--muted); text-align: right; }

.chapter-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; }

.chapter-card {
  --chapter-accent: #8ad8ff;
  min-height: 360px;
  display: flex;
  flex-direction: column;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 28px;
  background: linear-gradient(145deg, color-mix(in srgb, var(--chapter-accent) 10%, transparent), var(--card) 45%);
  box-shadow: var(--shadow);
}

.chapter-card.locked { opacity: 0.65; filter: saturate(0.62); }
.chapter-card.complete { border-color: color-mix(in srgb, var(--chapter-accent) 65%, transparent); }
.chapter-card-top { display: flex; justify-content: space-between; align-items: center; }
.chapter-number { color: var(--muted); font-size: 0.82rem; font-weight: 800; letter-spacing: 0.16em; }
.chapter-icon { color: var(--chapter-accent); font-size: 2.6rem; line-height: 1; filter: drop-shadow(0 0 12px var(--chapter-accent)); }
.chapter-card h3 { margin: 1.1rem 0 0.25rem; font-size: 1.75rem; }
.chapter-concept { color: var(--chapter-accent); font-size: 0.92rem; }
.chapter-card > p { min-height: 3.3em; color: var(--muted); line-height: 1.65; }

.chapter-progress { margin-top: auto; }
.chapter-progress > div:first-child { display: flex; justify-content: space-between; color: var(--muted); font-size: 0.83rem; }
.chapter-progress-track { height: 7px; margin-top: 8px; overflow: hidden; border-radius: 999px; background: rgba(255,255,255,0.08); }
.chapter-progress-track span { display: block; height: 100%; border-radius: inherit; background: var(--chapter-accent); }

.chapter-card-footer { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-top: 20px; }
.chapter-status { color: var(--muted); font-size: 0.8rem; }
.chapter-enter,
.chapter-card-footer button {
  min-width: 128px;
  padding: 0.76rem 1rem;
  border: 1px solid color-mix(in srgb, var(--chapter-accent) 55%, transparent);
  border-radius: 14px;
  color: var(--text);
  background: color-mix(in srgb, var(--chapter-accent) 18%, transparent);
  font-weight: 850;
  text-align: center;
  text-decoration: none;
}

.chapter-enter:hover,
.chapter-enter:focus-visible { background: color-mix(in srgb, var(--chapter-accent) 30%, transparent); transform: translateY(-1px); }

@media (max-width: 760px) {
  .hub-hero, .hub-section-heading { align-items: stretch; flex-direction: column; }
  .hub-section-heading > p { text-align: left; }
  .hub-summary { grid-template-columns: 1fr; }
  .chapter-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
  .hub-hero { padding: 26px 20px; }
  .hub-hero h1 { font-size: 2.7rem; }
  .chapter-card { min-height: 340px; padding: 20px; }
  .chapter-card-footer { align-items: stretch; flex-direction: column; }
}