/* ============================================================================
   lesson-resources.css — Lesson PDFs (student module pages) + Lesson
   PowerPoints (admin Teacher Reference).
   ----------------------------------------------------------------------------
   Token-driven only. No new colours, no gradients, no second design language —
   this is a reference library, so hierarchy and scanability lead.

   Inherits from studio-tokens.css: --ink, --ink-2, --muted, --accent,
   --accent-tint, --line, --line-strong, --surface, --surface-2, --font-mono.
   Course accent remapping comes from the .course-alg1 / .course-geo wrappers,
   so this file never hard-codes a course hue.
   ============================================================================ */

/* ------------------------------------------------------------ topic groups */

.lr-topics { display: flex; flex-direction: column; gap: 0.75rem; }

.lr-topic {
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface);
  overflow: hidden; /* keeps the header's rounded corners while open */
}

/* The disclosure control. A real <button> so Enter/Space and focus come free. */
.lr-topic-toggle {
  width: 100%;
  min-height: 44px;              /* touch target floor */
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  background: none;
  border: 0;
  text-align: left;
  cursor: pointer;
  color: var(--ink);
  font-family: inherit;
  transition: background .15s;
}
.lr-topic-toggle:hover { background: var(--accent-tint); }
.lr-topic-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.lr-topic-num {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-tint);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 0.28rem 0.5rem;
}

.lr-topic-title {
  flex: 1 1 auto;
  min-width: 0;                  /* lets long titles wrap instead of overflowing */
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.35;
}

.lr-topic-count {
  flex: none;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--muted);
}

/* Chevron rotates on expand. */
.lr-chevron {
  flex: none;
  width: 0.6rem; height: 0.6rem;
  border-right: 2px solid var(--muted);
  border-bottom: 2px solid var(--muted);
  transform: rotate(45deg);
  transition: transform .2s;
  margin-right: 0.15rem;
}
.lr-topic-toggle[aria-expanded="true"] .lr-chevron { transform: rotate(-135deg); }

.lr-topic-panel { border-top: 1px solid var(--line); }
.lr-topic-panel[hidden] { display: none; }

/* ---------------------------------------------------------------- lessons */

.lr-lessons { list-style: none; margin: 0; padding: 0; }

.lr-lesson {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.8rem 1rem;
  border-top: 1px solid var(--line);
}
.lr-lesson:first-child { border-top: 0; }

.lr-lesson-main { flex: 1 1 auto; min-width: 0; }

.lr-lesson-title {
  display: block;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--ink);
  line-height: 1.4;
}

.lr-lesson-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 0.7rem;
  margin-top: 0.3rem;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--muted);
}

.lr-type {
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--accent);
}

.lr-actions { flex: none; display: flex; gap: 0.5rem; align-items: center; }

.lr-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  min-height: 44px;
  padding: 0.5rem 0.95rem;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--surface-2);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.03em;
  text-decoration: none;
  cursor: pointer;
  transition: background .15s, border-color .15s, transform .15s;
}
.lr-btn:hover { background: var(--accent-tint); border-color: var(--accent); transform: translateY(-1px); }
.lr-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.lr-btn--primary { background: var(--accent-tint); border-color: var(--line-strong); color: var(--accent); }
.lr-btn[aria-disabled="true"] { opacity: .55; pointer-events: none; }

/* --------------------------------------------------------- states / notes */

.lr-state {
  padding: 1.1rem 1rem;
  border: 1px dashed var(--line);
  border-radius: 12px;
  color: var(--ink-2);
  font-size: 0.92rem;
  line-height: 1.6;
  background: var(--surface);
}
.lr-state--error { border-style: solid; }

.lr-attrib {
  margin: 1.1rem 0 0;
  font-size: 0.78rem;
  line-height: 1.55;
  color: var(--muted);
}
.lr-attrib a { color: var(--accent); }

.lr-count {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--muted);
  letter-spacing: 0.04em;
}

/* ------------------------------------------------------------- responsive */

/* Below 640px the action button goes full width under the metadata, so nothing
   is squeezed and nothing scrolls sideways at 320px. */
@media (max-width: 640px) {
  .lr-lesson { flex-direction: column; align-items: stretch; gap: 0.65rem; }
  .lr-actions { width: 100%; }
  .lr-btn { flex: 1 1 auto; width: 100%; }
  .lr-topic-count { display: none; }   /* count already shown per topic panel */
}

@media (prefers-reduced-motion: reduce) {
  .lr-topic-toggle, .lr-btn, .lr-chevron { transition: none; }
  .lr-btn:hover { transform: none; }
}

/* ===========================================================================
   Admin Teacher Reference — reuses the primitives above, adds filters and a
   wide-screen table. Scoped under .lr-admin so nothing leaks onto the site.
   =========================================================================== */

.lr-admin-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-bottom: 1.1rem;
}

.lr-seg { display: inline-flex; border: 1px solid var(--line); border-radius: 8px; overflow: hidden; }
.lr-seg button {
  min-height: 44px;
  padding: 0.5rem 1rem;
  border: 0;
  background: var(--surface);
  color: var(--ink-2);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 600;
  cursor: pointer;
}
.lr-seg button + button { border-left: 1px solid var(--line); }
.lr-seg button[aria-pressed="true"] { background: var(--accent-tint); color: var(--accent); }
.lr-seg button:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }

.lr-admin-controls select,
.lr-admin-controls input[type="search"] {
  min-height: 44px;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink);
  font-family: inherit;
  font-size: 0.88rem;
}
.lr-admin-controls input[type="search"] { flex: 1 1 220px; min-width: 0; }
.lr-admin-controls select:focus-visible,
.lr-admin-controls input[type="search"]:focus-visible {
  outline: 2px solid var(--accent); outline-offset: 1px;
}

.lr-group-head {
  margin: 1.5rem 0 0.6rem;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--ink);
}
.lr-crumb {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--muted);
  letter-spacing: 0.03em;
}