/* ═══════════════════════════════════════════════════════════════
   SECTION UI — a topic that holds multiple pages, navigated by a
   centered pill dropdown at the top of the content area (e.g. Unit
   1.1 Number Systems). Design matches the 1.1.x preview pages.
   ═══════════════════════════════════════════════════════════════ */

/* Section pages were authored with their own .wrap (max-width:760px).
   Inside the app the content-container already handles width (1400px),
   so let section pages fill it like every other page does. */
.section-page .wrap { max-width: none; margin: 0; }

/* ── persistent section header (SVG hero above the dropdown) ── */
.section-header { margin-bottom: 0.5rem; }
.section-header:empty { display: none; }

/* ── centered pill dropdown ── */
.unit-dropdown-wrap { position: relative; display: flex; justify-content: center; margin-bottom: 1.25rem; }
.unit-dropdown-btn {
  display: flex; align-items: center; gap: 0.5rem;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.15);
  color: rgba(255,255,255,0.65);
  font-family: 'Outfit', sans-serif;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  padding: 0.45rem 0.9rem;
  border-radius: 999px;
  cursor: pointer;
  transition: all 0.15s;
}
.unit-dropdown-btn:hover { background: rgba(255,255,255,0.1); border-color: rgba(255,255,255,0.3); color: #fff; }
.unit-dropdown-chevron { transition: transform 0.15s; flex-shrink: 0; }
.unit-dropdown-wrap.open .unit-dropdown-chevron { transform: rotate(180deg); }
.unit-dropdown-menu {
  position: absolute; top: calc(100% + 6px); left: 50%; transform: translateX(-50%);
  background: #111; border: 1px solid rgba(255,255,255,0.15); border-radius: 10px;
  padding: 0.4rem; min-width: 230px; display: none; flex-direction: column; gap: 2px;
  z-index: 30; box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}
.unit-dropdown-wrap.open .unit-dropdown-menu { display: flex; }
.unit-dropdown-item {
  display: flex; justify-content: space-between; align-items: center; gap: 0.6rem;
  padding: 0.5rem 0.7rem; border-radius: 6px; font-size: 0.85rem; font-weight: 600;
  color: rgba(255,255,255,0.7); text-decoration: none; font-family: 'Outfit', sans-serif;
  cursor: pointer; white-space: nowrap;
}
.unit-dropdown-item:hover { background: rgba(255,255,255,0.08); color: #fff; }
.unit-dropdown-item.active { color: var(--c-cyan); background: rgba(var(--c-cyan-rgb),0.08); }
.unit-dropdown-item.disabled { color: rgba(255,255,255,0.25); cursor: default; }
.unit-dropdown-item.disabled:hover { background: none; color: rgba(255,255,255,0.25); }
.unit-dropdown-item .soon {
  font-size: 0.6rem; text-transform: uppercase; letter-spacing: 0.5px; color: rgba(255,255,255,0.25);
  border: 1px solid rgba(255,255,255,0.15); padding: 0.1rem 0.35rem; border-radius: 999px;
}

/* ── page swap ── */
.section-page { animation: sectionFade 0.25s ease; }
@keyframes sectionFade { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }