/* ==========================================================================
 * single-lp_lesson.php — 無料コースの学習ビュー (issue #72)
 *
 * App-like full-bleed 3-column layout: roadmap rail / main / course rail.
 *
 * PALETTE SCOPING — body carries `zone-free` (TEAL). The mockup is BLUE +
 * gold + green. We declare the BLUE token override DIRECTLY on `.lesson-view`
 * (same mechanism `.home-v2` uses): a directly matched custom-property
 * declaration wins over the value inherited from `body.zone-free`, even though
 * `body.zone-free`(0,1,1) is more specific — that specificity only governs the
 * *inheritance* path, while a rule written straight onto `.lesson-view` sets
 * the property on the element itself. NEVER escalate to !important.
 * ========================================================================== */

.lesson-view {
  --color-primary:        #1E40AF;
  --color-accent:         #2563EB;
  --color-accent-light:   #93C5FD;
  --color-accent-bg:      #EFF6FF;
  --color-secondary:      #FACC15;
  --color-secondary-bg:   #FEF9C3;

  --color-bg:             #F8FAFC;
  --color-surface:        #FFFFFF;
  --color-border:         #E2E8F0;

  --color-text-primary:   #0F172A;
  --color-text-body:      #334155;
  --color-text-secondary: #475569;
  --color-text-muted:     #94A3B8;

  --zone-accent-primary:  #2563EB;
  --zone-radius-card:     14px;
  --shadow-card:          0 4px 14px rgba(15, 23, 42, 0.06);

  /* learning-view status colors */
  --lv-done:       #15803D;
  --lv-done-bg:    #DCFCE7;
  --lv-current:    #2563EB;
  --lv-current-bg: #EFF6FF;

  background: var(--color-bg);
  color: var(--color-text-body);
  min-height: 60vh;
}

/* --- LearnPress popup-mode scroll fix -----------------------------------
 * A lesson opened at /courses/<c>/lessons/<l>/ is a LearnPress course-item
 * view, so the body carries `course-item-popup`. LearnPress's CSS sets
 * `body.course-item-popup{overflow-y:hidden}` because it normally renders its
 * own inner scroll container — but this template paints normal-flow content
 * directly, so that rule traps everything below the fold (content after
 * "この講座で学ぶこと" became unreachable). Re-enable page scroll. The
 * `html` prefix lifts specificity to (0,1,2) so it beats LearnPress's (0,1,1)
 * regardless of stylesheet load order — no !important needed. This file only
 * loads on the lesson view (lp_is_lesson_view), so other popup pages are
 * untouched. */
html body.course-item-popup { overflow-y: auto; }

/* a11y helper (theme has no global .screen-reader-text guarantee here) */
.lesson-view .screen-reader-text {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

/* keyboard focus ring — consistent across the whole view */
.lesson-view a:focus-visible,
.lesson-view button:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: 6px;
}

/* --- shell + breadcrumb ------------------------------------------------- */
.lesson-view__shell {
  max-width: 1480px;
  margin: 0 auto;
  padding: var(--space-5) var(--space-6) var(--space-10);
}

.lesson-view__empty {
  text-align: center;
  color: var(--color-text-muted);
  padding: var(--space-10) 0;
}
.lesson-view__empty a { color: var(--color-accent); }

.lesson-view__breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-size: var(--text-caption);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
}
.lesson-view__crumb {
  color: var(--color-text-secondary);
  text-decoration: none;
}
.lesson-view__crumb:hover { color: var(--color-accent); }
.lesson-view__crumb--current {
  color: var(--color-text-primary);
  font-weight: var(--weight-semibold);
}
.lesson-view__crumb-sep { color: var(--color-text-muted); }

/* --- 3-column grid ------------------------------------------------------ */
.lesson-view__grid {
  display: grid;
  grid-template-columns: 22% minmax(0, 1fr) 24%;
  gap: var(--space-6);
  align-items: start;
}

/* --- shared card / button primitives ------------------------------------ */
.lesson-view__card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--zone-radius-card);
  box-shadow: var(--shadow-card);
  padding: var(--space-5);
}
.lesson-view__card + .lesson-view__card { margin-top: var(--space-4); }
.lesson-view__card-title {
  font-size: var(--text-body);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  margin: 0 0 var(--space-4);
}

.lesson-view__btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  font-size: var(--text-caption);
  font-weight: var(--weight-semibold);
  line-height: 1.4;
  text-decoration: none;
  text-align: center;
  padding: 10px var(--space-4);
  border-radius: 10px;
  border: 1.5px solid transparent;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}
.lesson-view__btn--solid {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}
.lesson-view__btn--solid:hover { background: var(--color-primary); border-color: var(--color-primary); }
.lesson-view__btn--outline {
  background: var(--color-surface);
  color: var(--color-accent);
  border-color: var(--color-border);
}
.lesson-view__btn--outline:hover { border-color: var(--color-accent); background: var(--color-accent-bg); }
.lesson-view__btn--block { display: flex; width: 100%; }
.lesson-view__btn.is-disabled {
  color: var(--color-text-muted);
  border-color: var(--color-border);
  background: var(--color-bg);
  cursor: not-allowed;
  pointer-events: none;
}

/* ======================== LEFT RAIL: roadmap nav ======================== */
.lesson-view__rail--left { display: block; }

.lesson-view__back {
  display: inline-block;
  font-size: var(--text-caption);
  font-weight: var(--weight-semibold);
  color: var(--color-accent);
  text-decoration: none;
  margin-bottom: var(--space-4);
}
.lesson-view__back:hover { text-decoration: underline; }

.lesson-view__roadmap-card { margin-bottom: var(--space-4); }
.lesson-view__roadmap-head {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-bottom: 6px;
}
.lesson-view__roadmap-icon { font-size: 18px; line-height: 1; }
.lesson-view__roadmap-label {
  font-size: var(--text-body);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
}
.lesson-view__roadmap-meta {
  font-size: var(--text-tiny);
  color: var(--color-text-secondary);
  margin: 0 0 var(--space-3);
  line-height: 1.5;
}

/* horizontal progress bar (roadmap summary) */
.lesson-view__progress {
  position: relative;
  height: 8px;
  border-radius: 999px;
  background: var(--color-accent-bg);
  overflow: hidden;
}
.lesson-view__progress-fill {
  position: absolute;
  inset: 0 auto 0 0;
  height: 100%;
  background: var(--color-accent);
  border-radius: 999px;
}
.lesson-view__progress-label {
  font-size: var(--text-tiny);
  color: var(--color-accent);
  font-weight: var(--weight-semibold);
  margin: 6px 0 0;
}

/* step list */
.lesson-view__steps {
  list-style: none;
  margin: 0 0 var(--space-4);
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.lesson-view__step {
  border: 1px solid var(--color-border);
  border-radius: 12px;
  background: var(--color-surface);
  overflow: hidden;
}
.lesson-view__step--current { border-color: var(--color-accent); }
.lesson-view__step-head {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
  padding: 12px var(--space-4);
  font-size: var(--text-caption);
}
.lesson-view__step--locked .lesson-view__step-head { color: var(--color-text-muted); }
.lesson-view__step-num {
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
}
.lesson-view__step--locked .lesson-view__step-num { color: var(--color-text-secondary); }
.lesson-view__step-title {
  flex: 1 1 auto;
  color: var(--color-text-body);
}
.lesson-view__step--current .lesson-view__step-title { font-weight: var(--weight-semibold); color: var(--color-text-primary); }
.lesson-view__step-lock { font-size: 12px; }
.lesson-view__step-count {
  font-size: var(--text-tiny);
  color: var(--color-text-muted);
}

.lesson-view__step--expanded {
  background: var(--color-accent-bg);
  border-color: var(--color-accent);
}
.lesson-view__step-lessons {
  list-style: none;
  margin: 0;
  padding: 0 var(--space-2) var(--space-2);
}
.lesson-view__step-lesson a,
.lesson-view__lessonlist-item a {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: 8px 10px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--color-text-body);
  font-size: var(--text-caption);
  line-height: 1.4;
}
.lesson-view__step-lesson a:hover,
.lesson-view__lessonlist-item a:hover { background: rgba(37, 99, 235, 0.06); }

/* current lesson row highlight */
.lesson-view__step-lesson--current > a,
.lesson-view__lessonlist-item--current > a {
  background: var(--lv-current-bg);
  color: var(--lv-current);
  font-weight: var(--weight-semibold);
}

/* status icon chips */
.lesson-view__li-icon {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  font-size: 11px;
  line-height: 1;
}
.lesson-view__li-icon--done    { background: var(--lv-done-bg);    color: var(--lv-done); }
.lesson-view__li-icon--current { background: var(--lv-current);    color: #fff; }
.lesson-view__li-icon--todo    { background: var(--color-border);  color: var(--color-text-muted); }

.lesson-view__li-no {
  flex: 0 0 auto;
  font-variant-numeric: tabular-nums;
  font-weight: var(--weight-semibold);
  color: inherit;
  opacity: 0.85;
}
.lesson-view__li-title {
  flex: 1 1 auto;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.lesson-view__li-dur {
  flex: 0 0 auto;
  font-size: var(--text-tiny);
  color: var(--color-text-muted);
}

/* ============================ CENTER: main ============================== */
.lesson-view__main { min-width: 0; }

.lesson-view__lesson-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-4);
}
.lesson-view__title {
  font-size: clamp(20px, 2.4vw, 26px);
  font-weight: var(--weight-bold);
  line-height: 1.4;
  color: var(--color-text-primary);
  margin: 0;
}
.lesson-view__fav {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: 999px;
  padding: 6px 14px;
  font-size: var(--text-caption);
  font-weight: var(--weight-semibold);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: border-color 0.15s ease, color 0.15s ease;
}
.lesson-view__fav:hover { border-color: var(--color-secondary); color: var(--color-text-primary); }
.lesson-view__fav[aria-pressed="true"] { color: var(--color-accent); border-color: var(--color-accent); } /* blue active state — yellow (--color-secondary) text on white surface fails AA */

.lesson-view__lesson-meta {
  font-size: var(--text-caption);
  color: var(--color-text-secondary);
  margin: var(--space-2) 0 var(--space-4);
}

/* responsive 16:9 player */
.lesson-view__player {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #0F172A;
  border-radius: var(--zone-radius-card);
  overflow: hidden;
  box-shadow: var(--shadow-card);
}
.lesson-view__player-frame,
.lesson-view__player-poster {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}
.lesson-view__player-poster {
  background-size: cover;
  background-position: center;
  display: grid;
  place-items: center;
}
.lesson-view__player-poster--empty { background: linear-gradient(135deg, #1E293B, #334155); }
.lesson-view__player-play {
  width: 64px;
  height: 64px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: rgba(37, 99, 235, 0.92);
  color: #fff;
  font-size: 24px;
  padding-left: 4px;
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
}

/* tab bar */
.lesson-view__tabs {
  display: flex;
  gap: var(--space-1);
  border-bottom: 1px solid var(--color-border);
  margin-top: var(--space-5);
  overflow-x: auto;
  scrollbar-width: none;
}
.lesson-view__tabs::-webkit-scrollbar { display: none; }
.lesson-view__tab {
  flex: 0 0 auto;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: 10px var(--space-4);
  font-size: var(--text-caption);
  font-weight: var(--weight-semibold);
  color: var(--color-text-secondary);
  cursor: pointer;
  white-space: nowrap;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.lesson-view__tab:hover { color: var(--color-text-primary); }
.lesson-view__tab.is-active {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* panels */
.lesson-view__panel { padding-top: var(--space-5); }
.lesson-view__panel[hidden] { display: none; }
.lesson-view__panel-placeholder {
  color: var(--color-text-muted);
  font-size: var(--text-caption);
  padding: var(--space-6) 0;
}
.lesson-view__panel-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
  flex-wrap: wrap;
}
.lesson-view__panel-title {
  font-size: var(--text-h3);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  margin: 0;
}
.lesson-view__memo-btn {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  background: var(--color-accent-bg);
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 6px 14px;
  font-size: var(--text-tiny);
  font-weight: var(--weight-semibold);
  color: var(--color-accent);
  cursor: pointer;
  transition: background 0.15s ease;
}
.lesson-view__memo-btn:hover { background: var(--color-accent-light); }

.lesson-view__learn-list {
  list-style: none;
  margin: 0 0 var(--space-6);
  padding: var(--space-4);
  background: var(--color-accent-bg);
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.lesson-view__learn-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-2);
  font-size: var(--text-caption);
  color: var(--color-text-body);
  line-height: 1.6;
}
.lesson-view__learn-check {
  flex: 0 0 auto;
  width: 18px;
  height: 18px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: var(--lv-done-bg);
  color: var(--lv-done);
  font-size: 11px;
  margin-top: 1px;
}

/* lesson body */
.lesson-view__body {
  font-size: var(--text-body);
  line-height: 1.9;
  color: var(--color-text-body);
}
.lesson-view__body h2,
.lesson-view__body h3 {
  color: var(--color-text-primary);
  font-weight: var(--weight-bold);
  margin: var(--space-6) 0 var(--space-3);
  line-height: 1.5;
}
.lesson-view__body h2 { font-size: var(--text-h2); }
.lesson-view__body h3 { font-size: var(--text-h3); }
.lesson-view__body h4 {
  font-size: var(--text-body);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  margin: var(--space-5) 0 var(--space-2);
  line-height: 1.5;
}
.lesson-view__body p { margin: 0 0 var(--space-4); }
.lesson-view__body a { color: var(--color-accent); }
.lesson-view__body a:hover { text-decoration: underline; }
.lesson-view__body strong { font-weight: var(--weight-bold); color: var(--color-text-primary); }
.lesson-view__body ul,
.lesson-view__body ol { margin: 0 0 var(--space-4) var(--space-5); padding-left: var(--space-4); }
.lesson-view__body ul { list-style: disc; }
.lesson-view__body ol { list-style: decimal; }
.lesson-view__body li { margin: 0 0 6px; }
.lesson-view__body img { max-width: 100%; height: auto; border-radius: 10px; }
.lesson-view__body iframe { max-width: 100%; }

/* Markdown-rendered code (fenced blocks + inline) */
.lesson-view__body :not(pre) > code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Courier New", monospace;
  font-size: 0.88em;
  background: var(--color-accent-bg);
  color: var(--color-primary);
  padding: 0.15em 0.4em;
  border-radius: 5px;
  word-break: break-word;
}
.lesson-view__body pre {
  margin: 0 0 var(--space-4);
  padding: var(--space-4);
  background: #0F172A;
  color: #E2E8F0;
  border-radius: 12px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  line-height: 1.7;
}
.lesson-view__body pre code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Courier New", monospace;
  font-size: 0.86em;
  background: none;
  color: inherit;
  padding: 0;
  white-space: pre;
}
.lesson-view__body blockquote {
  margin: 0 0 var(--space-4);
  padding: var(--space-3) var(--space-4);
  border-left: 4px solid var(--color-accent-light);
  background: var(--color-accent-bg);
  border-radius: 0 10px 10px 0;
  color: var(--color-text-secondary);
}
.lesson-view__body blockquote p:last-child { margin-bottom: 0; }
.lesson-view__body hr {
  border: 0;
  border-top: 1px solid var(--color-border);
  margin: var(--space-6) 0;
}

/* ======================== 確認クイズ (interactive) ===================== */
.lesson-view__body .lesson-quiz {
  margin: var(--space-6) 0 0;
  padding: var(--space-5);
  background: var(--color-accent-bg);
  border: 1px solid var(--color-accent-light);
  border-radius: var(--zone-radius-card);
}
.lesson-view__body .lesson-quiz__title {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin: 0 0 var(--space-1);
  font-size: var(--text-h3);
  color: var(--color-primary);
}
.lesson-view__body .lesson-quiz__title-icon { font-size: 0.9em; }
.lesson-view__body .lesson-quiz__lead {
  margin: 0 0 var(--space-4);
  font-size: var(--text-tiny);
  color: var(--color-text-secondary);
}

.lesson-view__body .lesson-quiz__item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: var(--space-4);
}
.lesson-view__body .lesson-quiz__item + .lesson-quiz__item { margin-top: var(--space-4); }

.lesson-view__body .lesson-quiz__q {
  display: flex;
  gap: var(--space-2);
  align-items: baseline;
  margin: 0 0 var(--space-3);
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
  line-height: 1.6;
}
.lesson-view__body .lesson-quiz__qnum {
  flex: 0 0 auto;
  font-size: var(--text-caption);
  font-weight: var(--weight-bold);
  color: #fff;
  background: var(--color-accent);
  border-radius: 6px;
  padding: 2px 8px;
  line-height: 1.5;
}
.lesson-view__body .lesson-quiz__qtext { flex: 1 1 auto; }

.lesson-view__body .lesson-quiz__choices {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.lesson-view__body .lesson-quiz__choices li { margin: 0; }

.lesson-view__body .lesson-quiz__choice {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  width: 100%;
  text-align: left;
  padding: 12px var(--space-3);
  background: var(--color-surface);
  border: 1.5px solid var(--color-border);
  border-radius: 10px;
  font-size: var(--text-caption);
  color: var(--color-text-body);
  line-height: 1.5;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.lesson-view__body .lesson-quiz__choice:hover:not(:disabled) {
  border-color: var(--color-accent);
  background: var(--color-accent-bg);
}
.lesson-view__body .lesson-quiz__choice:disabled { cursor: default; }

.lesson-view__body .lesson-quiz__choice-key {
  flex: 0 0 auto;
  width: 26px;
  height: 26px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: var(--weight-bold);
  color: var(--color-text-secondary);
  background: var(--color-bg);
  border-radius: 50%;
}
.lesson-view__body .lesson-quiz__choice-text { flex: 1 1 auto; }
.lesson-view__body .lesson-quiz__choice-mark {
  flex: 0 0 auto;
  width: 1.2em;
  text-align: center;
  font-weight: var(--weight-bold);
}

/* answered states */
.lesson-view__body .lesson-quiz__choice.is-correct {
  border-color: var(--lv-done);
  background: var(--lv-done-bg);
  color: var(--color-text-primary);
}
.lesson-view__body .lesson-quiz__choice.is-correct .lesson-quiz__choice-key {
  color: #fff;
  background: var(--lv-done);
}
.lesson-view__body .lesson-quiz__choice.is-correct .lesson-quiz__choice-mark::after { content: "✓"; color: var(--lv-done); }
.lesson-view__body .lesson-quiz__choice.is-wrong {
  border-color: #DC2626;
  background: #FEF2F2;
}
.lesson-view__body .lesson-quiz__choice.is-wrong .lesson-quiz__choice-key {
  color: #fff;
  background: #DC2626;
}
.lesson-view__body .lesson-quiz__choice.is-wrong .lesson-quiz__choice-mark::after { content: "✕"; color: #DC2626; }

.lesson-view__body .lesson-quiz__result { margin-top: var(--space-3); }
.lesson-view__body .lesson-quiz__verdict {
  margin: 0 0 var(--space-2);
  font-weight: var(--weight-bold);
}
.lesson-view__body .lesson-quiz__verdict.is-correct { color: var(--lv-done); }
.lesson-view__body .lesson-quiz__verdict.is-wrong { color: #DC2626; }

.lesson-view__body .lesson-quiz__explanation {
  font-size: var(--text-caption);
  color: var(--color-text-body);
  line-height: 1.8;
  background: var(--color-bg);
  border-radius: 10px;
  padding: var(--space-3) var(--space-4);
}
.lesson-view__body .lesson-quiz__explanation-label {
  display: inline-block;
  font-weight: var(--weight-bold);
  color: var(--color-primary);
  margin-right: var(--space-2);
}

/* footer nav */
.lesson-view__footer-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: var(--space-3);
  align-items: stretch;
  margin-top: var(--space-8);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-border);
}
.lesson-view__nav-prev { justify-content: flex-start; text-align: left; }
.lesson-view__nav-next { justify-content: flex-end; text-align: right; }
.lesson-view__nav-prev,
.lesson-view__nav-next {
  flex-direction: column;
  align-items: flex-start;
  gap: 2px;
  padding: 10px var(--space-4);
}
.lesson-view__nav-next { align-items: flex-end; }
.lesson-view__nav-sub {
  display: block;
  font-size: var(--text-tiny);
  font-weight: var(--weight-regular);
  color: inherit;
  opacity: 0.8;
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.lesson-view__nav-complete { white-space: nowrap; }

/* ============================ RIGHT RAIL =============================== */
.lesson-view__rail--right { display: block; }

/* donut/ring via conic-gradient */
.lesson-view__ring-wrap {
  display: flex;
  justify-content: center;
  margin-bottom: var(--space-3);
}
.lesson-view__ring {
  --lv-ring-pct: 0;
  position: relative;
  width: 120px;
  height: 120px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background:
    conic-gradient(var(--color-accent) calc(var(--lv-ring-pct) * 1%), var(--color-accent-bg) 0);
}
.lesson-view__ring::before {
  content: "";
  position: absolute;
  width: 86px;
  height: 86px;
  border-radius: 50%;
  background: var(--color-surface);
}
.lesson-view__ring-num {
  position: relative;
  z-index: 1;
  font-size: 24px;
  font-weight: var(--weight-bold);
  color: var(--color-text-primary);
}
.lesson-view__progress-detail {
  text-align: center;
  font-size: var(--text-tiny);
  color: var(--color-text-secondary);
  margin: 0 0 var(--space-4);
  line-height: 1.6;
}

.lesson-view__lessonlist {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.lesson-view__help-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.lesson-view__help-links a {
  font-size: var(--text-caption);
  color: var(--color-accent);
  text-decoration: none;
  font-weight: var(--weight-semibold);
}
.lesson-view__help-links a:hover { text-decoration: underline; }

/* ============================ RESPONSIVE =============================== */

/* tablet: drop right rail under, keep 2 columns */
@media (max-width: 1280px) {
  .lesson-view__grid {
    grid-template-columns: 26% minmax(0, 1fr);
  }
  .lesson-view__rail--right {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-4);
    align-items: start;
  }
  .lesson-view__rail--right .lesson-view__card + .lesson-view__card { margin-top: 0; }
}

/* single column under ~1100px: main first, then course list, then roadmap */
@media (max-width: 1100px) {
  .lesson-view__grid {
    display: flex;
    flex-direction: column;
  }
  .lesson-view__main { order: 1; }
  .lesson-view__rail--right { order: 2; display: block; }
  .lesson-view__rail--right .lesson-view__card + .lesson-view__card { margin-top: var(--space-4); }
  .lesson-view__rail--left { order: 3; }
}

@media (max-width: 640px) {
  .lesson-view__shell { padding: var(--space-4) var(--space-4) var(--space-8); }
  .lesson-view__lesson-head { flex-direction: column; }
  .lesson-view__footer-nav {
    grid-template-columns: 1fr;
  }
  .lesson-view__nav-prev,
  .lesson-view__nav-next { align-items: stretch; text-align: center; }
  .lesson-view__nav-next { justify-content: center; }
  .lesson-view__nav-prev { justify-content: center; }
}

/* reduced motion */
@media (prefers-reduced-motion: reduce) {
  .lesson-view * { transition: none !important; }
}