/* Long-form lesson reading typography. Optimized for Tamil + mobile. */

.lesson-wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 16px;
}
.lesson-hero {
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
  margin-bottom: 24px;
}
.lesson-hero .crumbs {
  font-size: .85rem;
  color: var(--ink-dim);
  margin-bottom: 6px;
}
.lesson-hero h1 {
  font-size: 2rem;
  line-height: 1.25;
  margin: 0 0 8px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.lesson-hero .meta {
  color: var(--ink-dim); font-size: .9rem;
  display: flex; gap: 16px; flex-wrap: wrap;
}
.lesson-hero .meta .pill {
  background: var(--bg-soft); padding: 3px 10px; border-radius: 99px; font-size: .8rem;
}

.lesson-body {
  font-size: 17px;
  line-height: 1.85;
}
.lesson-body p {
  margin: 0 0 1.1em;
}
.lesson-body h2 {
  font-size: 1.4rem;
  margin: 1.8em 0 .6em;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
  color: var(--accent);
}
.lesson-body h3 {
  font-size: 1.15rem;
  margin: 1.6em 0 .4em;
  color: var(--accent-2);
}
.lesson-body h4 {
  font-size: 1rem;
  margin: 1.2em 0 .3em;
  color: var(--ink);
  font-weight: 700;
}
.lesson-body ul, .lesson-body ol {
  padding-left: 22px;
  margin: 0 0 1.1em;
}
.lesson-body li { margin-bottom: .35em; }

.callout {
  border-left: 4px solid var(--accent);
  background: var(--bg-soft);
  padding: 14px 18px;
  border-radius: 8px;
  margin: 18px 0;
}
.callout.tip      { border-color: var(--accent); }
.callout.warn     { border-color: var(--warn); }
.callout.trap     { border-color: var(--bad); }
.callout.memory   { border-color: var(--accent-2); }
.callout.examiner { border-color: var(--good); }
.callout > .label {
  font-weight: 700;
  font-size: .85rem;
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-bottom: 6px;
  color: var(--ink-dim);
}

.equation {
  display: block;
  text-align: center;
  font-family: "Cambria Math", "Latin Modern Math", serif;
  font-size: 1.15rem;
  background: var(--bg-soft);
  padding: 12px;
  border-radius: 8px;
  margin: 14px 0;
  overflow-x: auto;
}

.term {
  color: var(--accent);
  font-weight: 600;
  cursor: help;
}
.term .en {
  color: var(--ink-dim);
  font-style: italic;
  font-weight: 400;
  font-size: .92em;
}

.svg-frame {
  background: #0d1228;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 18px;
  margin: 18px 0;
  text-align: center;
}
.svg-frame .caption {
  margin-top: 10px;
  font-size: .85rem;
  color: var(--ink-dim);
  font-style: italic;
}

.section-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin: 32px 0 8px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}
.section-nav a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: var(--card);
  border-radius: 10px;
  border: 1px solid var(--line);
  flex: 1;
}
.section-nav a.next { justify-content: flex-end; text-align: right; }
.section-nav a:hover { border-color: var(--accent); text-decoration: none; }
.section-nav .arrow { color: var(--accent); font-size: 1.3rem; }
.section-nav .label { font-size: .75rem; color: var(--ink-dim); display: block; }
.section-nav .title { font-weight: 600; }

.unit-toc {
  display: grid;
  gap: 10px;
}
.unit-toc .toc-item {
  display: flex; gap: 12px;
  padding: 12px 14px;
  background: var(--card);
  border-radius: 10px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--line);
}
.unit-toc .toc-item:hover { border-color: var(--accent); }
.unit-toc .toc-item .code {
  font-family: monospace;
  color: var(--accent);
  font-weight: 700;
  min-width: 42px;
}
.unit-toc .toc-item .meta {
  color: var(--ink-dim);
  font-size: .85rem;
  margin-left: auto;
}

.exam-yield {
  display: inline-block;
  color: var(--warn);
  letter-spacing: 1px;
}

/* MCQ trainer */
.mcq-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 22px;
  margin-bottom: 16px;
}
.mcq-card .stem {
  font-size: 1.05rem;
  margin-bottom: 14px;
  line-height: 1.6;
}
.mcq-card .opt {
  display: block;
  padding: 12px 16px;
  margin-bottom: 8px;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  border-radius: 10px;
  cursor: pointer;
  transition: all .15s;
}
.mcq-card .opt:hover { border-color: var(--accent); }
.mcq-card .opt.correct { border-color: var(--good); background: rgba(74,222,128,.08); }
.mcq-card .opt.wrong   { border-color: var(--bad);  background: rgba(248,113,113,.08); }
.mcq-card .opt .why {
  display: none;
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid var(--line);
  font-size: .9rem;
  color: var(--ink-dim);
}
.mcq-card.revealed .opt .why { display: block; }
.mcq-card .deep-expl {
  display: none;
  margin-top: 16px;
  padding: 14px;
  background: var(--bg-soft);
  border-radius: 8px;
  border-left: 3px solid var(--accent);
}
.mcq-card.revealed .deep-expl { display: block; }

/* Revision modes */
.revision-tabs {
  display: flex; gap: 6px; margin-bottom: 18px; flex-wrap: wrap;
}
.revision-tabs button {
  background: var(--bg-soft);
  border: 1px solid var(--line);
  color: var(--ink-dim);
  padding: 8px 16px;
  border-radius: 99px;
  cursor: pointer;
  font: inherit;
  font-size: .9rem;
}
.revision-tabs button.active {
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  color: #0b1020; border: 0; font-weight: 700;
}
.revision-pane { display: none; }
.revision-pane.active { display: block; }

/* Exam summary panel (per-section) */
.exam-summary {
  margin: 36px 0 12px;
  padding: 18px 20px;
  background: linear-gradient(180deg, rgba(125,211,252,.08), rgba(192,132,252,.05));
  border: 1px solid var(--accent);
  border-left-width: 4px;
  border-radius: 12px;
}
.exam-summary-head {
  display: flex; flex-wrap: wrap; gap: 8px;
  margin-bottom: 14px;
}
.exam-summary-head .badge {
  background: var(--bg-soft);
  border: 1px solid var(--line);
  padding: 4px 10px;
  border-radius: 99px;
  font-size: .82rem;
  color: var(--ink-dim);
}
.exam-summary-head .badge:first-child {
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  color: #0b1020;
  border-color: transparent;
  font-weight: 700;
}
.exam-summary-row {
  font-size: .9rem;
  color: var(--ink-dim);
  margin-bottom: 10px;
}
.exam-summary-row .lbl { font-weight: 600; color: var(--ink); margin-right: 6px; }
.exam-summary-block {
  background: var(--bg-soft);
  border-radius: 8px;
  padding: 12px 14px;
  margin-bottom: 10px;
}
.exam-summary-block.traps { border-left: 3px solid var(--bad); }
.exam-summary-block .block-title {
  font-size: .85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .04em;
  color: var(--ink-dim);
  margin-bottom: 6px;
}
.exam-summary-block ul { margin: 0; padding-left: 20px; }
.exam-summary-block li { margin-bottom: 4px; line-height: 1.5; }
.exam-summary-tldr {
  margin-top: 8px;
  padding: 10px 14px;
  background: rgba(125,211,252,.08);
  border-radius: 8px;
  border-left: 3px solid var(--accent);
  font-size: .95rem;
}
.exam-summary-tldr .tldr-label {
  font-weight: 700;
  margin-right: 6px;
  color: var(--accent);
}