/* ============================================================================
   lessons.css  —  Stylesheet for the /lessons section of legost.in
   ----------------------------------------------------------------------------
   Loaded ONLY on /lessons pages, AFTER Bootstrap 5.3 (light) and style.css.
   Adds a refined "course reader" design layer without touching the rest of
   the site. Plain CSS (no Sass). Self-contained: system fonts, no @import.

   Sections:
     1.  Design tokens (CSS custom properties)
     2.  Scoped base + helpers
     3.  Catalog index  (/lessons)
     4.  Course page    (/lessons/{id})
     5.  Lesson reader  (/lessons/{id}/{n})  — column, breadcrumb, pager, TOC
     6.  Lesson content typography  (.lesson-content)
     7.  Tables & figures
     8.  Diagrams (mermaid) + video + math
     9.  Server-rendered tests / reveal / checkpoint / recall widgets
     10. Interactive template widgets (tpl-*) + flashcards
     11. Responsive breakpoints
     12. Print styles
   ========================================================================== */


/* ============================================================================
   1. DESIGN TOKENS
   ========================================================================== */
:root {
  /* Palette — harmonised with the host site */
  --ls-bg:            #f6f6f6;
  --ls-surface:       #ffffff;
  --ls-surface-2:     #f1f4f9;
  --ls-surface-hover: #eef2f8;
  --ls-border:        #e5e9f0;
  --ls-border-strong: #d3dae5;

  --ls-text:          #1f2733;
  --ls-text-muted:    #5b6573;
  --ls-text-subtle:   #8a93a3;

  --ls-primary:       #0b63ce;
  --ls-primary-hover: #0951ab;
  --ls-primary-soft:  #e8f1fc;
  --ls-primary-ink:   #084a9c;

  --ls-accent:        #0b63ce;   /* keep brand-blue accent for cohesion */
  --ls-accent-soft:   #e8f1fc;

  --ls-ok:            #1f8a5b;
  --ls-ok-soft:       #e8f6ef;
  --ls-ok-ink:        #155f3f;
  --ls-danger:        #d4334a;
  --ls-danger-soft:   #fdecef;
  --ls-danger-ink:    #9b1f33;
  --ls-warn:          #b67400;

  /* Dark code surface */
  --ls-code-bg:       #0d1117;
  --ls-code-fg:       #e6edf3;
  --ls-code-border:   #1d2530;

  /* Typography */
  --ls-font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
             Arial, "Apple Color Emoji", "Segoe UI Emoji", sans-serif;
  --ls-font-serif: Georgia, "Times New Roman", "Iowan Old Style", serif;
  --ls-font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
                  "Liberation Mono", monospace;

  /* Shape + depth */
  --ls-radius:    14px;
  --ls-radius-md: 12px;
  --ls-radius-sm: 10px;
  --ls-radius-xs: 8px;
  --ls-shadow:    0 1px 2px rgba(20, 28, 40, 0.04), 0 4px 16px rgba(20, 28, 40, 0.06);
  --ls-shadow-lg: 0 10px 34px rgba(20, 28, 40, 0.12);
  --ls-ring:      0 0 0 3px rgba(11, 99, 206, 0.22);

  /* Reading measure */
  --ls-read-width: 720px;
}


/* ============================================================================
   2. SCOPED BASE + HELPERS
   Everything is scoped under .lessons-page so we never leak onto other routes.
   ========================================================================== */
.lessons-page {
  background: var(--ls-bg);
  color: var(--ls-text);
  font-family: var(--ls-font);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  font-variant-numeric: tabular-nums;
}

.lessons-page a {
  color: var(--ls-primary);
  text-decoration: none;
  transition: color 0.14s ease;
}
.lessons-page a:hover { color: var(--ls-primary-hover); text-decoration: underline; }

/* Accessible focus rings everywhere inside the section */
.lessons-page a:focus-visible,
.lessons-page button:focus-visible,
.lessons-page input:focus-visible,
.lessons-page select:focus-visible,
.lessons-page summary:focus-visible,
.lessons-page [tabindex]:focus-visible {
  outline: 2px solid var(--ls-primary);
  outline-offset: 2px;
  border-radius: 6px;
}

.lessons-page .ls-muted   { color: var(--ls-text-muted); }
.lessons-page .ls-subtle  { color: var(--ls-text-subtle); }
.lessons-page .ls-serif   { font-family: var(--ls-font-serif); }

/* A constrained, centered wrapper used across page types */
.lessons-page .ls-shell { max-width: 1120px; margin: 0 auto; padding: 32px 24px 64px; }

/* Generic eyebrow / section label */
.lessons-page .ls-eyebrow {
  display: inline-block;
  color: var(--ls-primary);
  font-size: 12px;
  font-weight: 750;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* Pills / badges (shared by catalog + course header) */
.lessons-page .ls-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 3px 10px;
  border-radius: 999px;
  background: var(--ls-surface-2);
  border: 1px solid var(--ls-border);
  color: var(--ls-text-muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.02em;
  line-height: 1.6;
  white-space: nowrap;
}
.lessons-page .ls-badge.is-primary { background: var(--ls-primary-soft); border-color: transparent; color: var(--ls-primary-ink); }
.lessons-page .ls-badge.is-solid   { background: var(--ls-primary); border-color: transparent; color: #fff; }
.lessons-page .ls-badge.is-upper   { text-transform: uppercase; }

/* Buttons (lightweight; complements Bootstrap's .btn) */
.lessons-page .ls-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 40px;
  padding: 8px 16px;
  border-radius: var(--ls-radius-xs);
  border: 1px solid var(--ls-primary);
  background: var(--ls-primary);
  color: #fff;
  font-weight: 650;
  font-size: 14px;
  cursor: pointer;
  transition: background 0.14s ease, border-color 0.14s ease, transform 0.05s ease;
}
.lessons-page .ls-btn:hover { background: var(--ls-primary-hover); border-color: var(--ls-primary-hover); text-decoration: none; color: #fff; }
.lessons-page .ls-btn:active { transform: translateY(1px); }
.lessons-page .ls-btn.is-ghost {
  background: var(--ls-surface);
  color: var(--ls-text);
  border-color: var(--ls-border-strong);
}
.lessons-page .ls-btn.is-ghost:hover { background: var(--ls-surface-hover); color: var(--ls-text); }


/* ============================================================================
   3. CATALOG INDEX  (/lessons)
   Hero header, search/filter bar, premium course-card grid, empty state.
   ========================================================================== */

/* Hero header --------------------------------------------------------------- */
.lessons-page .catalog-hero {
  position: relative;
  padding: 8px 0 26px;
  margin-bottom: 28px;
  border-bottom: 1px solid var(--ls-border);
}
.lessons-page .catalog-hero h1 {
  margin: 10px 0 0;
  font-family: var(--ls-font-serif);
  font-size: clamp(32px, 5vw, 50px);
  font-weight: 700;
  line-height: 1.04;
  letter-spacing: -0.02em;
  max-width: 18ch;
}
.lessons-page .catalog-lead {
  margin: 14px 0 0;
  max-width: 60ch;
  color: var(--ls-text-muted);
  font-size: 17px;
  line-height: 1.55;
  text-wrap: balance;
}

/* Search + filter bar ------------------------------------------------------- */
.lessons-page .catalog-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
  padding: 14px;
  margin-bottom: 26px;
  background: var(--ls-surface);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  box-shadow: var(--ls-shadow);
}
.lessons-page .catalog-search {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: 1 1 260px;
  height: 44px;
  padding: 0 14px;
  border: 1px solid var(--ls-border-strong);
  border-radius: 999px;
  background: var(--ls-surface);
  color: var(--ls-text-subtle);
}
.lessons-page .catalog-search:focus-within { border-color: var(--ls-primary); box-shadow: var(--ls-ring); }
.lessons-page .catalog-search input {
  flex: 1;
  min-width: 0;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--ls-text);
  font-size: 15px;
}
.lessons-page .catalog-filters { display: flex; flex-direction: column; align-items: stretch; gap: 10px; }
.lessons-page .catalog-filter-group { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.lessons-page .catalog-filter-group .group-label {
  flex: 0 0 auto;
  min-width: 80px;
  color: var(--ls-text-subtle);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .filter-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  border-radius: 999px;
  border: 1px solid var(--ls-border-strong);
  background: var(--ls-surface);
  color: var(--ls-text-muted);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: border-color 0.14s ease, color 0.14s ease, background 0.14s ease;
}
.lessons-page .filter-chip:hover { border-color: var(--ls-primary); color: var(--ls-primary); text-decoration: none; }
.lessons-page .filter-chip.is-active { background: var(--ls-primary); border-color: var(--ls-primary); color: #fff; }
.lessons-page .filter-chip .chip-count { opacity: 0.7; font-size: 11px; }

/* Premium course-card grid (Bootstrap .card lives inside each cell) --------- */
.lessons-page .course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  align-items: stretch;
}

/* Elevate the Bootstrap card into a premium tile while keeping .card markup */
.lessons-page .course-grid .card {
  display: flex;
  flex-direction: column;
  min-width: 0;
  height: 100%;
  background: var(--ls-surface);
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  box-shadow: var(--ls-shadow);
  overflow: hidden;
  transition: transform 0.16s ease, box-shadow 0.16s ease, border-color 0.16s ease;
}
.lessons-page .course-grid .card:hover {
  transform: translateY(-3px);
  box-shadow: var(--ls-shadow-lg);
  border-color: var(--ls-border-strong);
}

/* Cover image */
.lessons-page .course-card-cover {
  display: block;
  aspect-ratio: 16 / 9;
  background: var(--ls-surface-2);
  overflow: hidden;
}
.lessons-page .course-card-cover img,
.lessons-page .course-grid .card-img-top {
  width: 100%;
  height: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  display: block;
}
/* Monogram fallback cover when no image is supplied */
.lessons-page .course-card-cover.is-mono {
  display: grid;
  place-items: center;
  background: linear-gradient(135deg, #11365f, #0b63ce);
  color: #fff;
  font-family: var(--ls-font-serif);
  font-size: 42px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.lessons-page .course-grid .card-body {
  display: flex;
  flex-direction: column;
  gap: 9px;
  padding: 18px;
  flex: 1;
}
.lessons-page .course-card-topic {
  margin: 0;
  color: var(--ls-text-subtle);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .course-grid .card-title {
  margin: 0;
  font-family: var(--ls-font-serif);
  font-size: 21px;
  line-height: 1.16;
}
.lessons-page .course-grid .card-title a { color: var(--ls-text); }
.lessons-page .course-grid .card-title a:hover { color: var(--ls-primary); text-decoration: none; }
.lessons-page .course-grid .card-text {
  margin: 0;
  color: var(--ls-text-muted);
  font-size: 14px;
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* Badge row for language / format / lesson-count */
.lessons-page .course-card-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 2px;
}

/* Card footer: lesson count meta + open action */
.lessons-page .course-card-foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-top: auto;
  padding-top: 12px;
  border-top: 1px solid var(--ls-border);
}
.lessons-page .course-card-count {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  color: var(--ls-text-muted);
  font-size: 12px;
  font-weight: 650;
}
.lessons-page .course-card-open { font-weight: 700; font-size: 13px; color: var(--ls-primary); }
.lessons-page .course-card-open:hover { text-decoration: none; }

/* Empty state -------------------------------------------------------------- */
.lessons-page .catalog-empty {
  grid-column: 1 / -1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 48px 28px;
  text-align: center;
  color: var(--ls-text-muted);
  border: 1px dashed var(--ls-border-strong);
  border-radius: var(--ls-radius);
  background: var(--ls-surface);
}
.lessons-page .catalog-empty .empty-icon { font-size: 32px; opacity: 0.55; }
.lessons-page .catalog-empty strong { color: var(--ls-text); font-size: 17px; font-family: var(--ls-font-serif); }


/* ============================================================================
   4. COURSE PAGE  (/lessons/{id})
   Course header (title, badges, cover) + modules→lessons table of contents.
   ========================================================================== */
.lessons-page .course-shell { max-width: 920px; margin: 0 auto; padding: 32px 24px 64px; }

.lessons-page .course-header {
  margin: 0 0 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--ls-border);
}
.lessons-page .course-header .course-cover {
  display: block;
  width: 100%;
  aspect-ratio: 21 / 9;
  margin-bottom: 22px;
  object-fit: cover;
  border-radius: var(--ls-radius);
  border: 1px solid var(--ls-border);
  background: var(--ls-surface-2);
}
.lessons-page .course-breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 7px;
  margin: 0 0 14px;
  color: var(--ls-text-subtle);
  font-size: 13px;
}
.lessons-page .course-breadcrumbs a { color: var(--ls-text-muted); }
.lessons-page .course-breadcrumbs a:hover { color: var(--ls-text); }
.lessons-page .course-breadcrumbs .sep { opacity: 0.5; }
.lessons-page .course-breadcrumbs [aria-current="page"] { color: var(--ls-text); font-weight: 650; }

.lessons-page .course-header h1 {
  margin: 0 0 12px;
  font-family: var(--ls-font-serif);
  font-size: clamp(30px, 4.4vw, 44px);
  font-weight: 700;
  line-height: 1.05;
  letter-spacing: -0.02em;
  max-width: 22ch;
}
.lessons-page .course-topic {
  margin: 0 0 14px;
  color: var(--ls-primary);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .course-intro {
  margin: 0 0 18px;
  max-width: 64ch;
  color: var(--ls-text-muted);
  font-size: 17px;
  line-height: 1.6;
}
.lessons-page .course-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
}

/* Course quick-stats strip (lessons / modules / duration) */
.lessons-page .course-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 12px;
  margin: 26px 0;
}
.lessons-page .course-stat {
  padding: 14px 16px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
}
.lessons-page .course-stat strong {
  display: block;
  font-family: var(--ls-font-serif);
  font-size: 24px;
  line-height: 1.1;
  color: var(--ls-text);
}
.lessons-page .course-stat span {
  display: block;
  margin-top: 2px;
  color: var(--ls-text-muted);
  font-size: 12px;
}

/* Table of contents: modules → lessons (Bootstrap .list-group inside) ------- */
.lessons-page .course-toc { margin-top: 8px; }
.lessons-page .course-toc-heading {
  margin: 0 0 16px;
  font-family: var(--ls-font-serif);
  font-size: 22px;
  font-weight: 700;
}

.lessons-page .toc-module { margin: 0 0 22px; }
.lessons-page .toc-module-head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin: 0 0 8px;
}
.lessons-page .toc-module-num {
  flex: 0 0 auto;
  color: var(--ls-text-subtle);
  font-family: var(--ls-font-serif);
  font-size: 18px;
  font-weight: 700;
}
.lessons-page .toc-module-title {
  margin: 0;
  font-size: 18px;
  font-weight: 700;
  line-height: 1.25;
}
.lessons-page .toc-module-summary {
  margin: 0 0 10px;
  color: var(--ls-text-muted);
  font-size: 14px;
  line-height: 1.5;
}

/* List-group of lessons — restyle Bootstrap items into scannable rows */
.lessons-page .course-toc .list-group {
  border-radius: var(--ls-radius-sm);
  overflow: hidden;
  box-shadow: var(--ls-shadow);
}
.lessons-page .course-toc .list-group-item {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
  padding: 13px 16px;
  border-color: var(--ls-border);
  color: var(--ls-text);
  background: var(--ls-surface);
  transition: background 0.14s ease;
}
.lessons-page .course-toc a.list-group-item:hover {
  background: var(--ls-surface-hover);
  text-decoration: none;
  z-index: 1;
}
.lessons-page .toc-lesson-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 999px;
  background: var(--ls-primary-soft);
  color: var(--ls-primary-ink);
  font-size: 13px;
  font-weight: 750;
}
.lessons-page .toc-lesson-body { min-width: 0; }
.lessons-page .toc-lesson-title {
  margin: 0;
  font-size: 15px;
  font-weight: 650;
  line-height: 1.3;
}
.lessons-page .toc-lesson-summary {
  margin: 2px 0 0;
  color: var(--ls-text-muted);
  font-size: 13px;
  line-height: 1.45;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.lessons-page .toc-lesson-chevron { color: var(--ls-text-subtle); font-size: 16px; }
.lessons-page .course-toc a.list-group-item:hover .toc-lesson-chevron { color: var(--ls-primary); }


/* ============================================================================
   5. LESSON READER  (/lessons/{id}/{n})
   Centered reading column, breadcrumb, module eyebrow, prev/next, sticky TOC.
   ========================================================================== */

/* Optional two-column layout: sticky sidebar + reading column on wide screens */
.lessons-page .lesson-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 36px;
  max-width: 1180px;
  margin: 0 auto;
  padding: 28px 24px 72px;
}
@media (min-width: 1080px) {
  .lessons-page .lesson-layout.has-toc {
    grid-template-columns: 260px minmax(0, 1fr);
  }
}

/* Sticky lesson list sidebar (.lesson-toc) — degrades gracefully if absent */
.lessons-page .lesson-toc {
  align-self: start;
  position: sticky;
  top: 24px;
  max-height: calc(100vh - 48px);
  overflow-y: auto;
  padding: 16px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius);
  background: var(--ls-surface);
  box-shadow: var(--ls-shadow);
}
.lessons-page .lesson-toc-title {
  margin: 0 0 10px;
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ls-text-subtle);
}
.lessons-page .lesson-toc-list {
  list-style: none;
  margin: 0 0 2px;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
/* Module group heading inside the sidebar */
.lessons-page .lesson-toc-module {
  margin: 14px 0 4px;
  padding: 0 9px;
  color: var(--ls-text-subtle);
  font-size: 10.5px;
  font-weight: 750;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}
.lessons-page .lesson-toc-title + .lesson-toc-module { margin-top: 4px; }
.lessons-page .lesson-toc li { min-width: 0; }
.lessons-page .lesson-toc a {
  display: grid;
  grid-template-columns: 22px minmax(0, 1fr);
  gap: 8px;
  padding: 7px 9px;
  border-radius: var(--ls-radius-xs);
  color: var(--ls-text-muted);
  font-size: 13.5px;
  line-height: 1.35;
}
.lessons-page .lesson-toc-num {
  color: var(--ls-text-subtle);
  font-size: 12px;
  font-weight: 700;
  text-align: right;
  font-variant-numeric: tabular-nums;
}
.lessons-page .lesson-toc-text {
  min-width: 0;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.lessons-page .lesson-toc a:hover { background: var(--ls-surface-hover); color: var(--ls-text); text-decoration: none; }
.lessons-page .lesson-toc a:hover .lesson-toc-num { color: var(--ls-text-muted); }
.lessons-page .lesson-toc a.is-active,
.lessons-page .lesson-toc .active > a {
  background: var(--ls-primary-soft);
  color: var(--ls-primary-ink);
  font-weight: 650;
}
.lessons-page .lesson-toc a.is-active .lesson-toc-num,
.lessons-page .lesson-toc .active > a .lesson-toc-num { color: var(--ls-primary); }

/* Below the two-column breakpoint the sidebar would stack a long lesson list
   above the article and bury the content — hide it and keep the reader
   content-first (navigation stays via breadcrumbs + prev/next pager). */
@media (max-width: 1079px) {
  .lessons-page .lesson-layout,
  .lessons-page .lesson-layout.has-toc { grid-template-columns: 1fr; }
  .lessons-page .lesson-toc { display: none; }
}

/* Reading column container */
.lessons-page .lesson-main { min-width: 0; }

/* Breadcrumb at top of a lesson */
.lessons-page .lesson-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 7px;
  margin: 0 auto 10px;
  max-width: var(--ls-read-width);
  color: var(--ls-text-subtle);
  font-size: 13px;
}
.lessons-page .lesson-crumbs a { color: var(--ls-text-muted); }
.lessons-page .lesson-crumbs a:hover { color: var(--ls-text); }
.lessons-page .lesson-crumbs .sep { opacity: 0.5; }

/* Module eyebrow above the lesson title */
.lessons-page .lesson-eyebrow {
  display: block;
  max-width: var(--ls-read-width);
  margin: 0 auto 6px;
  color: var(--ls-primary);
  font-size: 12px;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

/* Prev / next pager */
.lessons-page .lesson-pager {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
  max-width: var(--ls-read-width);
  margin: 40px auto 0;
  padding-top: 22px;
  border-top: 1px solid var(--ls-border);
}
.lessons-page .lesson-pager-link {
  display: block;
  min-width: 0;
  padding: 14px 16px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  color: var(--ls-text);
  box-shadow: var(--ls-shadow);
  transition: border-color 0.14s ease, transform 0.14s ease, box-shadow 0.14s ease;
}
.lessons-page .lesson-pager-link:hover {
  border-color: var(--ls-border-strong);
  transform: translateY(-2px);
  box-shadow: var(--ls-shadow-lg);
  text-decoration: none;
}
.lessons-page .lesson-pager-link.next { text-align: right; }
.lessons-page .lesson-pager-link span {
  display: block;
  margin-bottom: 4px;
  color: var(--ls-text-subtle);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .lesson-pager-link strong {
  display: block;
  font-size: 15px;
  font-weight: 650;
  line-height: 1.35;
}
.lessons-page .lesson-pager-link.is-primary {
  border-color: var(--ls-primary);
  background: var(--ls-primary-soft);
  color: var(--ls-primary-ink);
}


/* ============================================================================
   6. LESSON CONTENT TYPOGRAPHY  (.lesson-content)
   Generous editorial reading: ~18px body, 1.75 line-height, ~720px measure.
   ========================================================================== */
.lessons-page .lesson-content {
  max-width: var(--ls-read-width);
  margin: 0 auto;
  font-size: 18px;
  line-height: 1.75;
  color: var(--ls-text);
}

.lessons-page .lesson-content > *:first-child { margin-top: 0; }

.lessons-page .lesson-content h1,
.lessons-page .lesson-content h2,
.lessons-page .lesson-content h3,
.lessons-page .lesson-content h4 {
  font-family: var(--ls-font-serif);
  line-height: 1.15;
  letter-spacing: -0.01em;
  color: var(--ls-text);
  scroll-margin-top: 24px;
}
.lessons-page .lesson-content h1 { margin: 0 0 0.5em; font-size: 2em; font-weight: 700; }
.lessons-page .lesson-content h2 {
  margin: 1.6em 0 0.5em;
  font-size: 1.55em;
  font-weight: 700;
  padding-bottom: 0.25em;
  border-bottom: 1px solid var(--ls-border);
}
.lessons-page .lesson-content h3 { margin: 1.4em 0 0.45em; font-size: 1.28em; font-weight: 700; }
.lessons-page .lesson-content h4 { margin: 1.3em 0 0.4em; font-size: 1.08em; font-weight: 700; }

.lessons-page .lesson-content p { margin: 0 0 1.1em; }

.lessons-page .lesson-content a { color: var(--ls-primary); text-decoration: underline; text-underline-offset: 2px; text-decoration-thickness: 1px; text-decoration-color: rgba(11, 99, 206, 0.4); }
.lessons-page .lesson-content a:hover { text-decoration-color: currentColor; }

.lessons-page .lesson-content strong { font-weight: 700; color: var(--ls-text); }
.lessons-page .lesson-content em { font-style: italic; }

.lessons-page .lesson-content ul,
.lessons-page .lesson-content ol { margin: 0 0 1.1em; padding-left: 1.5em; }
.lessons-page .lesson-content li { margin: 0.3em 0; }
.lessons-page .lesson-content li > ul,
.lessons-page .lesson-content li > ol { margin: 0.3em 0; }
.lessons-page .lesson-content hr { margin: 2.2em 0; border: 0; border-top: 1px solid var(--ls-border); }

/* Inline code */
.lessons-page .lesson-content :not(pre) > code {
  padding: 0.15em 0.42em;
  border-radius: 6px;
  background: var(--ls-surface-2);
  border: 1px solid var(--ls-border);
  font-family: var(--ls-font-mono);
  font-size: 0.86em;
  color: var(--ls-primary-ink);
  word-break: break-word;
}

/* Dark code blocks (#0d1117) */
.lessons-page .lesson-content pre,
.lessons-page .tpl-step-code {
  margin: 1.4em 0;
  padding: 16px 18px;
  border-radius: var(--ls-radius-sm);
  background: var(--ls-code-bg);
  border: 1px solid var(--ls-code-border);
  overflow-x: auto;
  font-family: var(--ls-font-mono);
  font-size: 14px;
  line-height: 1.6;
  color: var(--ls-code-fg);
  -webkit-overflow-scrolling: touch;
}
.lessons-page .lesson-content pre code {
  display: block;
  padding: 0;
  background: transparent;
  border: 0;
  color: inherit;
  font-size: inherit;
  white-space: pre;
}
/* highlight.js tokens render on top of the dark panel; keep panel bg. */
.lessons-page .lesson-content pre code.hljs { background: transparent; padding: 0; color: var(--ls-code-fg); }

/* Blockquote */
.lessons-page .lesson-content blockquote {
  margin: 1.5em 0;
  padding: 4px 0 4px 20px;
  border-left: 3px solid var(--ls-primary);
  color: var(--ls-text-muted);
  font-style: italic;
}
.lessons-page .lesson-content blockquote p:last-child { margin-bottom: 0; }

/* Images */
.lessons-page .lesson-content img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 1.6em auto;
  border-radius: var(--ls-radius-sm);
  border: 1px solid var(--ls-border);
  background: var(--ls-surface-2);
}


/* ============================================================================
   7. TABLES & FIGURES
   ========================================================================== */
.lessons-page .table-wrap {
  max-width: 100%;
  overflow-x: auto;
  margin: 1.6em 0;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  -webkit-overflow-scrolling: touch;
}
.lessons-page .lesson-content table {
  width: 100%;
  border-collapse: collapse;
  min-width: 460px;
  font-size: 15px;
  line-height: 1.5;
}
.lessons-page .lesson-content th,
.lessons-page .lesson-content td {
  padding: 11px 14px;
  border-bottom: 1px solid var(--ls-border);
  border-right: 1px solid var(--ls-border);
  vertical-align: top;
  text-align: left;
}
.lessons-page .lesson-content th:last-child,
.lessons-page .lesson-content td:last-child { border-right: 0; }
/* Keep inline code in cells on one line so identifiers don't break apart
   char-by-char in a narrow column — the table scrolls horizontally instead. */
.lessons-page .lesson-content th code,
.lessons-page .lesson-content td code { white-space: nowrap; word-break: normal; }
.lessons-page .lesson-content tr:last-child td { border-bottom: 0; }
.lessons-page .lesson-content thead th {
  background: var(--ls-surface-2);
  font-weight: 750;
  color: var(--ls-text);
}
.lessons-page .lesson-content tbody tr:nth-child(even) { background: rgba(241, 244, 249, 0.45); }

.lessons-page .lesson-content figure { margin: 1.8em 0; }
.lessons-page .lesson-content figure img { margin: 0; }
.lessons-page .lesson-content figcaption {
  margin-top: 8px;
  color: var(--ls-text-muted);
  font-size: 13px;
  line-height: 1.45;
  text-align: center;
}


/* ============================================================================
   8. DIAGRAMS (mermaid) + VIDEO + MATH
   Same class names as the reference so the hydration JS matches.
   ========================================================================== */
.lessons-page .diagram { width: 100%; margin: 1.6em 0; }
.lessons-page .mermaid-frame {
  width: 100%;
  padding: 18px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  overflow: auto;
}
.lessons-page .mermaid-frame.rendered { cursor: zoom-in; }
/* .mermaid-source is just a data holder — never show it */
.lessons-page .mermaid-source { display: none; }
.lessons-page .mermaid-output { display: flex; justify-content: center; min-width: 260px; }
.lessons-page .mermaid-output svg { max-width: 100%; height: auto; }
/* Fallback (raw text) shows until JS renders, then hides */
.lessons-page .mermaid-fallback {
  margin: 0;
  padding: 4px;
  white-space: pre;
  overflow-x: auto;
  color: var(--ls-text-muted);
  font-family: var(--ls-font-mono);
  font-size: 13px;
}
.lessons-page .mermaid-frame.rendered .mermaid-fallback { display: none; }
.lessons-page .mermaid-frame.failed .mermaid-output { display: none; }
.lessons-page .mermaid-error {
  display: none;
  margin: 8px 0 0;
  color: var(--ls-danger);
  font-family: var(--ls-font-mono);
  font-size: 12px;
}
.lessons-page .mermaid-frame.failed .mermaid-error { display: block; }
.lessons-page .mermaid-frame.rendered::after {
  content: "⤢";
  position: absolute;
  top: 8px;
  right: 8px;
  width: 26px;
  height: 26px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 7px;
  background: rgba(13, 17, 23, 0.6);
  color: #fff;
  font-size: 14px;
  opacity: 0;
  transition: opacity 0.14s ease;
  pointer-events: none;
}
.lessons-page .mermaid-frame { position: relative; }
.lessons-page .mermaid-frame.rendered:hover::after { opacity: 1; }

/* Fullscreen zoom/pan lightbox (mermaid diagrams open here) ----------------- */
html.laa-zoom-open { overflow: hidden; }
.laa-zoom-overlay {
  position: fixed;
  inset: 0;
  z-index: 1080;
  display: flex;
  flex-direction: column;
  background: rgba(13, 17, 23, 0.94);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
}
.laa-zoom-overlay[hidden] { display: none; }
.laa-zoom-toolbar {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
  padding: 12px 14px;
  flex: 0 0 auto;
}
.laa-zoom-btn {
  width: 42px;
  height: 42px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid rgba(255, 255, 255, 0.25);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
  font-size: 19px;
  font-weight: 700;
  line-height: 1;
  cursor: pointer;
  transition: background 0.14s ease, border-color 0.14s ease;
}
.laa-zoom-btn:hover { background: rgba(255, 255, 255, 0.22); border-color: rgba(255, 255, 255, 0.55); }
.laa-zoom-btn:focus-visible { outline: 2px solid #fff; outline-offset: 2px; }
.laa-zoom-viewport {
  flex: 1 1 auto;
  position: relative;
  overflow: hidden;
  touch-action: none;
  cursor: grab;
}
.laa-zoom-viewport:active { cursor: grabbing; }
.laa-zoom-stage {
  position: absolute;
  top: 0;
  left: 0;
  transform-origin: 0 0;
  will-change: transform;
}
.laa-zoom-stage svg { display: block; background: #fff; border-radius: 8px; }

/* Video embeds */
.lessons-page .video-widget { width: 100%; margin: 1.6em 0; }
.lessons-page .video-frame {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: #0b0e14;
  overflow: hidden;
}
.lessons-page .video-frame iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

/* Server-rendered KaTeX math */
.lessons-page .math-block {
  margin: 1.5em 0;
  overflow-x: auto;
  overflow-y: hidden;
}
.lessons-page .math-block .katex-display { margin: 0; }
.lessons-page .katex { font-size: 1.05em; }


/* ============================================================================
   9. SERVER-RENDERED TESTS / REVEAL / CHECKPOINT / RECALL
   Adapted from reference; class names preserved for JS hydration.
   ========================================================================== */

/* Shared widget container chrome */
.lessons-page .widget,
.lessons-page .widget-checkpoint,
.lessons-page .widget-recall {
  margin: 1.8em 0;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  box-shadow: var(--ls-shadow);
  overflow: hidden;
}

/* --- Test widget ---------------------------------------------------------- */
.lessons-page .test {
  margin: 1.8em 0;
  padding: 20px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  box-shadow: var(--ls-shadow);
}
.lessons-page .test > h3 {
  margin: 0 0 14px;
  font-family: var(--ls-font-serif);
  font-size: 22px;
}
.lessons-page .test-questions { display: grid; gap: 18px; margin: 0; padding: 0; list-style: none; }
.lessons-page .test-question { margin: 0; }
.lessons-page .test-question-text { margin: 0 0 9px; font-weight: 700; }
.lessons-page .test-options { display: grid; gap: 8px; }
.lessons-page .test-option {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  padding: 10px 12px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-xs);
  background: var(--ls-surface);
  cursor: pointer;
  transition: border-color 0.14s ease, background 0.14s ease;
}
.lessons-page .test-option:hover { border-color: var(--ls-border-strong); }
.lessons-page .test-option input { margin-top: 3px; }
.lessons-page .test-option.chosen { border-color: var(--ls-primary); background: var(--ls-primary-soft); }
.lessons-page .test-option.correct { border-color: var(--ls-ok); background: var(--ls-ok-soft); color: var(--ls-ok-ink); }
.lessons-page .test-option.wrong { border-color: var(--ls-danger); background: var(--ls-danger-soft); color: var(--ls-danger-ink); }
.lessons-page .test-explanation {
  margin-top: 9px;
  padding: 9px 12px;
  border-left: 3px solid var(--ls-primary);
  border-radius: 6px;
  background: var(--ls-surface-2);
  color: var(--ls-text-muted);
  font-size: 14px;
}
.lessons-page .test-actions { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-top: 16px; }
.lessons-page .test-submit,
.lessons-page .test-retake {
  min-height: 38px;
  padding: 8px 16px;
  border-radius: var(--ls-radius-xs);
  border: 1px solid var(--ls-primary);
  background: var(--ls-primary);
  color: #fff;
  font: inherit;
  font-size: 14px;
  font-weight: 650;
  cursor: pointer;
  transition: background 0.14s ease;
}
.lessons-page .test-submit:hover,
.lessons-page .test-retake:hover { background: var(--ls-primary-hover); }
.lessons-page .test-retake { background: var(--ls-surface); color: var(--ls-text); border-color: var(--ls-border-strong); }
.lessons-page .test-retake:hover { background: var(--ls-surface-hover); }
.lessons-page .test-submit:disabled { opacity: 0.5; cursor: not-allowed; }
.lessons-page .test-result { font-size: 14px; font-weight: 700; }
.lessons-page .test-result.pass { color: var(--ls-ok); }
.lessons-page .test-result.fail { color: var(--ls-danger); }

/* --- Reveal widget -------------------------------------------------------- */
/* The reveal lives inside the .widget/.widget-recall/.widget-checkpoint card,
   which already provides the border/background — keep this inner block flat to
   avoid a card-in-a-card look. */
.lessons-page .reveal {
  margin: 0;
  padding: 16px;
  border: 0;
  border-radius: 0;
  background: transparent;
}
.lessons-page .reveal-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
  color: var(--ls-text-subtle);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .reveal-q { margin: 0 0 12px; font-weight: 650; }
.lessons-page .reveal-btn {
  min-height: 36px;
  padding: 7px 14px;
  border: 1px solid var(--ls-border-strong);
  border-radius: var(--ls-radius-xs);
  background: var(--ls-surface-2);
  color: var(--ls-text);
  font: inherit;
  font-size: 14px;
  font-weight: 650;
  cursor: pointer;
  transition: background 0.14s ease, border-color 0.14s ease;
}
.lessons-page .reveal-btn:hover { background: var(--ls-surface-hover); border-color: var(--ls-primary); }
.lessons-page .reveal-a {
  margin-top: 12px;
  padding: 12px 14px;
  border-left: 3px solid var(--ls-primary);
  border-radius: 6px;
  background: var(--ls-surface-2);
  color: var(--ls-text);
}
.lessons-page .reveal-a > :first-child { margin-top: 0; }
.lessons-page .reveal-a > :last-child { margin-bottom: 0; }

/* --- Checkpoint + recall widgets ------------------------------------------ */
.lessons-page .widget-checkpoint-label,
.lessons-page .widget-recall-label {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 11px 14px;
  border-bottom: 1px solid var(--ls-border);
  background: var(--ls-surface-2);
  color: var(--ls-text-muted);
  font-size: 12px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .widget-checkpoint-question,
.lessons-page .widget-recall-question { padding: 14px 16px 4px; font-weight: 650; }
.lessons-page .widget-checkpoint-question > :first-child,
.lessons-page .widget-checkpoint-answer > :first-child,
.lessons-page .widget-recall-question > :first-child,
.lessons-page .widget-recall-answer > :first-child { margin-top: 0; }
.lessons-page .widget-checkpoint-question > :last-child,
.lessons-page .widget-checkpoint-answer > :last-child,
.lessons-page .widget-recall-question > :last-child,
.lessons-page .widget-recall-answer > :last-child { margin-bottom: 0; }
.lessons-page .widget-checkpoint-answer,
.lessons-page .widget-recall-answer {
  margin: 12px 16px 16px;
  padding: 12px 14px;
  border-left: 3px solid var(--ls-primary);
  border-radius: 6px;
  background: var(--ls-surface-2);
  color: var(--ls-text);
}


/* ============================================================================
   10. INTERACTIVE TEMPLATE WIDGETS  (tpl-*) + FLASHCARDS
   Hydrated client-side; class names match the reference exactly.
   ========================================================================== */

/* Widget shell + interactive header */
.lessons-page .widget,
.lessons-page .widget-template {
  margin: 1.8em 0;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  box-shadow: var(--ls-shadow);
  overflow: hidden;
}
.lessons-page .widget-interactive-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 11px 14px;
  border-bottom: 1px solid var(--ls-border);
  background: var(--ls-surface-2);
  color: var(--ls-text-muted);
  font-size: 12px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.lessons-page .widget-interactive-title { color: var(--ls-text); font-size: 13px; text-transform: none; letter-spacing: 0; }
.lessons-page .widget-id { margin-left: auto; color: var(--ls-text-subtle); font-family: var(--ls-font-mono); font-size: 11px; text-transform: none; }
.lessons-page .widget-interactive-desc { padding: 0 14px 12px; color: var(--ls-text-muted); font-size: 14px; }

/* Template body */
.lessons-page .tpl-body { display: flex; flex-direction: column; gap: 14px; padding: 16px; }
.lessons-page .tpl-prompt { font-size: 15px; color: var(--ls-text-muted); }

/* Quiz / fill-blank / order shared list resets */
.lessons-page .tpl-quiz,
.lessons-page .tpl-fillblank,
.lessons-page .tpl-order {
  margin: 0;
  padding-left: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.lessons-page .tpl-quiz-item { margin: 0; }
.lessons-page .tpl-quiz-q { margin: 0 0 8px; font-size: 15px; font-weight: 650; }
.lessons-page .tpl-options { display: flex; flex-direction: column; gap: 7px; }

/* Options / chips — interactive choosers */
.lessons-page .tpl-option,
.lessons-page .tpl-chip {
  padding: 9px 13px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-xs);
  background: var(--ls-surface);
  color: var(--ls-text);
  font: inherit;
  font-size: 14px;
  text-align: left;
  cursor: pointer;
  transition: border-color 0.14s ease, background 0.14s ease;
}
.lessons-page .tpl-option:hover:not(:disabled),
.lessons-page .tpl-chip:hover:not(:disabled) { border-color: var(--ls-primary); }
.lessons-page .tpl-option.correct,
.lessons-page .tpl-chip.correct,
.lessons-page .tpl-order-item.correct,
.lessons-page .tpl-fb-input.correct { border-color: var(--ls-ok); background: var(--ls-ok-soft); }
.lessons-page .tpl-option.wrong,
.lessons-page .tpl-chip.wrong,
.lessons-page .tpl-order-item.wrong,
.lessons-page .tpl-fb-input.wrong { border-color: var(--ls-danger); background: var(--ls-danger-soft); }
.lessons-page .tpl-chip.selected { border-color: var(--ls-primary); background: var(--ls-primary-soft); }
.lessons-page .tpl-chip.matched { opacity: 0.55; border-style: dashed; cursor: default; }

/* Explanation block (shared) */
.lessons-page .tpl-explanation {
  margin-top: 6px;
  padding: 9px 12px;
  border-left: 3px solid var(--ls-primary);
  border-radius: 6px;
  background: var(--ls-surface-2);
  font-size: 14px;
}

/* Footers / nav / toolbars */
.lessons-page .tpl-footer,
.lessons-page .tpl-nav,
.lessons-page .tpl-code-toolbar,
.lessons-page .tpl-code-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}
.lessons-page .tpl-check,
.lessons-page .tpl-reset,
.lessons-page .tpl-nav button,
.lessons-page .tpl-code-actions button {
  min-height: 36px;
  padding: 8px 15px;
  border: 1px solid var(--ls-border-strong);
  border-radius: var(--ls-radius-xs);
  background: var(--ls-surface);
  color: var(--ls-text);
  font: inherit;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.14s ease, border-color 0.14s ease;
}
.lessons-page .tpl-check { border-color: var(--ls-primary); color: var(--ls-primary); font-weight: 700; }
.lessons-page .tpl-check:hover:not(:disabled) { background: var(--ls-primary-soft); }
.lessons-page .tpl-reset:hover:not(:disabled),
.lessons-page .tpl-nav button:hover:not(:disabled),
.lessons-page .tpl-code-actions button:hover:not(:disabled) { background: var(--ls-surface-hover); }
.lessons-page .tpl-check:disabled,
.lessons-page .tpl-reset:disabled,
.lessons-page .tpl-nav button:disabled,
.lessons-page .tpl-code-actions button:disabled { opacity: 0.45; cursor: default; }
.lessons-page .tpl-score { font-size: 14px; font-weight: 700; }

/* Step walkthrough */
.lessons-page .tpl-step-head { display: flex; align-items: baseline; gap: 10px; }
.lessons-page .tpl-step-count { font-size: 12px; color: var(--ls-text-muted); }
.lessons-page .tpl-step-title { font-size: 15px; font-weight: 700; }
.lessons-page .tpl-step-text { font-size: 14px; color: var(--ls-text); }
/* .tpl-step-code uses the dark code panel defined in section 6 */
.lessons-page .tpl-step-code { font-size: 13px; }

/* Match columns */
.lessons-page .tpl-match-cols { display: flex; gap: 14px; flex-wrap: wrap; }
.lessons-page .tpl-match-col { flex: 1; min-width: 180px; display: flex; flex-direction: column; gap: 7px; }

/* Fill-in-the-blank */
.lessons-page .tpl-fb-item { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; font-size: 15px; }
.lessons-page .tpl-fb-text { font-size: 15px; }
.lessons-page .tpl-fb-input {
  width: 140px;
  margin: 0 4px;
  padding: 6px 10px;
  border: 1px solid var(--ls-border-strong);
  border-radius: 6px;
  background: var(--ls-surface);
  font: inherit;
  font-size: 14px;
}
.lessons-page .tpl-fb-input:focus { outline: 0; border-color: var(--ls-primary); box-shadow: var(--ls-ring); }
.lessons-page .tpl-hint-btn {
  padding: 3px 11px;
  border: 1px dashed var(--ls-border-strong);
  border-radius: 999px;
  background: none;
  color: var(--ls-text-muted);
  font: inherit;
  font-size: 12px;
  cursor: pointer;
}
.lessons-page .tpl-hint-btn:hover { border-color: var(--ls-primary); color: var(--ls-primary); }
.lessons-page .tpl-fb-answer { font-size: 13px; color: var(--ls-ok-ink); font-weight: 650; }

/* Ordering */
.lessons-page .tpl-order-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-xs);
  background: var(--ls-surface);
}
.lessons-page .tpl-order-text { flex: 1; font-size: 14px; }
.lessons-page .tpl-order-btns { display: flex; gap: 4px; }
.lessons-page .tpl-order-btns button {
  min-width: 30px;
  padding: 3px 9px;
  border: 1px solid var(--ls-border-strong);
  border-radius: 6px;
  background: var(--ls-surface);
  cursor: pointer;
}
.lessons-page .tpl-order-btns button:hover { background: var(--ls-surface-hover); }

/* Slider + live outputs */
.lessons-page .tpl-slider-row { display: flex; align-items: center; gap: 12px; font-size: 14px; }
.lessons-page .tpl-slider-row input[type="range"] { flex: 1; accent-color: var(--ls-primary); }
.lessons-page .tpl-slider-label { min-width: 96px; color: var(--ls-text-muted); }
.lessons-page .tpl-slider-value { min-width: 52px; text-align: right; font-variant-numeric: tabular-nums; font-weight: 650; }
.lessons-page .tpl-outputs {
  display: flex;
  flex-direction: column;
  gap: 9px;
  padding: 12px 14px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-xs);
  background: var(--ls-surface-2);
}
.lessons-page .tpl-output { display: flex; align-items: center; gap: 10px; font-size: 14px; }
.lessons-page .tpl-output-label { color: var(--ls-text-muted); }
.lessons-page .tpl-output-value { font-weight: 700; font-variant-numeric: tabular-nums; }
.lessons-page .tpl-bar { flex: 1; height: 8px; border-radius: 999px; background: var(--ls-border); overflow: hidden; }
.lessons-page .tpl-bar-fill { display: block; height: 100%; background: var(--ls-primary); transition: width 0.15s ease; }

/* Categorise / drag-into-bucket */
.lessons-page .tpl-cat-pool,
.lessons-page .tpl-cat-bucket-items { display: flex; flex-wrap: wrap; gap: 7px; }
.lessons-page .tpl-cat-buckets { display: flex; gap: 12px; flex-wrap: wrap; }
.lessons-page .tpl-cat-bucket {
  flex: 1;
  min-width: 150px;
  padding: 12px;
  border: 1px dashed var(--ls-border-strong);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface);
  transition: border-color 0.14s ease, background 0.14s ease;
}
.lessons-page .tpl-cat-bucket.droppable { border-color: var(--ls-primary); background: var(--ls-primary-soft); cursor: pointer; }
.lessons-page .tpl-cat-bucket-title { margin-bottom: 8px; font-size: 13px; font-weight: 700; }

/* Flashcards / flip cards */
.lessons-page .flashcard,
.lessons-page .tpl-flipcard {
  width: 100%;
  min-height: 140px;
  padding: 18px;
  border: 1px solid var(--ls-border);
  border-radius: var(--ls-radius-sm);
  background: var(--ls-surface-2);
  color: var(--ls-text);
  text-align: left;
  cursor: pointer;
  transition: border-color 0.14s ease, background 0.14s ease;
}
.lessons-page .flashcard:hover,
.lessons-page .tpl-flipcard:hover { border-color: var(--ls-primary); }
.lessons-page .tpl-flipcard.is-flipped { background: var(--ls-primary-soft); border-color: var(--ls-primary); }
.lessons-page .flashcard-face { font-size: 16px; font-weight: 650; }
.lessons-page .flashcard-hint { margin-top: 12px; color: var(--ls-text-muted); font-size: 12px; }

/* Code-task widget */
.lessons-page .tpl-code { display: flex; flex-direction: column; gap: 10px; }
.lessons-page .tpl-code-task { font-size: 14px; }
.lessons-page .tpl-code-hint-row,
.lessons-page .tpl-code-note { font-size: 12px; color: var(--ls-text-subtle); }
.lessons-page .tpl-code-badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 11px;
  border-radius: 999px;
  background: var(--ls-surface-2);
  border: 1px solid var(--ls-border);
  color: var(--ls-text-muted);
  font-size: 12px;
  font-weight: 700;
}


/* ============================================================================
   11. RESPONSIVE BREAKPOINTS
   ========================================================================== */
@media (max-width: 860px) {
  .lessons-page .ls-shell,
  .lessons-page .course-shell { padding: 22px 16px 56px; }
  .lessons-page .lesson-layout { padding: 22px 16px 56px; gap: 28px; }
  .lessons-page .catalog-toolbar { padding: 12px; }
  .lessons-page .course-grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 16px; }
  .lessons-page .lesson-content { font-size: 17px; line-height: 1.7; }
  .lessons-page .course-toc .list-group-item { grid-template-columns: 36px minmax(0, 1fr) auto; gap: 10px; padding: 12px; }
}

@media (max-width: 560px) {
  .lessons-page .catalog-search { flex-basis: 100%; }
  .lessons-page .course-grid { grid-template-columns: 1fr; }
  .lessons-page .lesson-content { font-size: 16.5px; }
  .lessons-page .lesson-content pre { font-size: 13px; padding: 14px; border-radius: var(--ls-radius-xs); }
  .lessons-page .tpl-slider-row { flex-direction: column; align-items: stretch; gap: 7px; }
  .lessons-page .lesson-pager { grid-template-columns: 1fr; }
  .lessons-page .lesson-pager-link.next { text-align: left; }
}


/* ============================================================================
   12. PRINT STYLES
   A clean, ink-friendly lesson printout: hide chrome, flatten code panels.
   ========================================================================== */
@media print {
  .lessons-page {
    background: #fff;
    color: #000;
    font-size: 12pt;
  }
  /* Hide navigation / interactive chrome that makes no sense on paper */
  .lessons-page .lesson-toc,
  .lessons-page .lesson-pager,
  .lessons-page .catalog-toolbar,
  .lessons-page .course-card-foot,
  .lessons-page .tpl-footer,
  .lessons-page .tpl-nav,
  .lessons-page .test-actions,
  .lessons-page .reveal-btn { display: none !important; }

  .lessons-page .lesson-layout { display: block; padding: 0; }
  .lessons-page .lesson-content { max-width: none; font-size: 12pt; line-height: 1.5; }

  /* Flatten the dark code panel for print legibility */
  .lessons-page .lesson-content pre,
  .lessons-page .tpl-step-code {
    background: #f4f4f4;
    color: #111;
    border: 1px solid #bbb;
    box-shadow: none;
  }
  .lessons-page .lesson-content pre code.hljs { color: #111; }

  /* Reveal hidden answers so a printed lesson is self-contained */
  .lessons-page .reveal-a,
  .lessons-page .widget-checkpoint-answer,
  .lessons-page .widget-recall-answer { display: block !important; }

  .lessons-page .card,
  .lessons-page .test,
  .lessons-page .widget,
  .lessons-page .widget-template,
  .lessons-page .mermaid-frame { box-shadow: none; }

  /* Avoid awkward page breaks inside key blocks */
  .lessons-page .lesson-content h1,
  .lessons-page .lesson-content h2,
  .lessons-page .lesson-content h3 { break-after: avoid; }
  .lessons-page .lesson-content pre,
  .lessons-page .lesson-content figure,
  .lessons-page .table-wrap,
  .lessons-page .test-question { break-inside: avoid; }

  .lessons-page a { color: #000; text-decoration: underline; }
}