/* ══════════════════════════════════════════════════════════════════
   SLIDE VIEWER — swipeable browser-friendly slides
   ══════════════════════════════════════════════════════════════════ */

.deck-body {
  background: #0F1A2B; /* fixed dark — never changes with dark mode toggle */
  overflow-x: hidden;
  overscroll-behavior: none;
}

/* ─── PRE-DECK ELEMENTS ON ALWAYS-DARK BACKGROUND ─────────────── */
.deck-body h1,
.deck-body .chapter-h1 { color: #FFFFFF !important; }
.deck-body .chapter-num { color: var(--amber); }
.deck-body .chapter-subtitle {
  color: rgba(255,255,255,.62);
  border-bottom-color: rgba(255,255,255,.1);
}
.deck-body .breadcrumb,
.deck-body .breadcrumb a,
.deck-body .breadcrumb span { color: rgba(255,255,255,.5); }
.deck-body .breadcrumb a:hover { color: rgba(255,255,255,.85); text-decoration: underline; }
.deck-body .breadcrumb strong { color: rgba(255,255,255,.88); }
.deck-body .chapter-nav { background: rgba(255,255,255,.04); border-bottom-color: rgba(255,255,255,.08); }
.deck-body .chapter-nav-btn { color: rgba(255,255,255,.6); }
.deck-body .chapter-nav-btn.active { color: var(--amber); border-bottom-color: var(--amber); }
.deck-body .chapter-nav-btn:hover { color: #FFFFFF; }

/* ─── DECK NAV BAR ─────────────────────────────────────────────── */
.deck-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(15, 26, 47, 0.96);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-top: 1px solid rgba(184, 134, 11, 0.3);
  padding: 12px 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 50;
  padding-bottom: calc(12px + env(safe-area-inset-bottom));
}
.deck-nav button {
  cursor: pointer;
  background: rgba(255,255,255,0.06);
  color: rgba(255,255,255,0.75);
  padding: 10px 14px;
  border-radius: 6px;
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  min-width: 60px;
  min-height: 40px;
  transition: background 0.15s, transform 0.1s;
  border: 1px solid rgba(255,255,255,0.08);
}
.deck-nav button:active {
  transform: scale(0.96);
  background: rgba(255,255,255,0.15);
}
.deck-nav button:disabled {
  opacity: 0.3;
  cursor: default;
}
.deck-nav .counter {
  flex: 1;
  text-align: center;
  color: white;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  letter-spacing: 1px;
}
.deck-nav .counter span { color: var(--accent); font-weight: 700; }

/* Progress bar at top of screen */
.deck-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: rgba(255,255,255,0.08);
  z-index: 50;
}
.deck-progress-fill {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width 0.3s ease-out;
}

/* ─── SLIDE CONTAINER ──────────────────────────────────────────── */
.deck-viewport {
  padding: 60px 20px 90px;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}
.slide {
  display: none;
  width: 100%;
  max-width: 800px;
  margin: 0 auto;
  animation: slideIn 0.35s ease-out;
}
.slide.active { display: block; }

@keyframes slideIn {
  from { opacity: 0; transform: translateX(20px); }
  to   { opacity: 1; transform: translateX(0); }
}

/* ─── SLIDE CARD ───────────────────────────────────────────────── */
.slide-card {
  background: var(--paper);
  border-radius: 8px;
  padding: 32px 28px;
  box-shadow: 0 20px 50px rgba(0,0,0,0.3);
  min-height: 60vh; min-height: 60dvh;
  border-top: 4px solid var(--accent);
}

/* ─── TITLE SLIDE (dark) ───────────────────────────────────────── */
.slide.title-slide .slide-card {
  background: var(--navy-deep);
  color: white;
  border-top: 4px solid var(--accent);
  text-align: left;
  padding: 56px 32px;
}
.slide.title-slide .chapter-num {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 700;
  margin-bottom: 20px;
}
.slide.title-slide h1 {
  color: white;
  font-size: 3.2rem;
  line-height: 1;
  margin-bottom: 20px;
}
.slide.title-slide .deck-sub {
  color: var(--accent);
  font-size: 1.2rem;
  margin-bottom: 32px;
}
.slide.title-slide .deck-level {
  display: inline-block;
  padding: 6px 14px;
  background: var(--accent);
  color: white;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  letter-spacing: 2px;
  text-transform: uppercase;
  font-weight: 700;
  border-radius: 3px;
}

/* ─── CONTENT SLIDE HEADER ────────────────────────────────────── */
.slide-header {
  border-left: 4px solid var(--accent);
  padding: 6px 0 6px 16px;
  margin-bottom: 24px;
}
.slide-header h2 {
  font-size: 1.8rem;
  line-height: 1.1;
  margin-bottom: 4px;
}
.slide-header .slide-sub {
  color: var(--muted-deep);
  font-size: 0.95rem;
  font-style: italic;
}

/* ─── FORMULA BLOCKS ───────────────────────────────────────────── */
.formula-block {
  background: var(--cream-deep);
  border-left: 4px solid var(--accent);
  padding: 12px 16px;
  margin-bottom: 12px;
  border-radius: 0 4px 4px 0;
  font-weight: 700;
  font-size: 0.98rem;
}
.formula-block .arrow {
  color: var(--muted);
  margin: 0 8px;
}
.formula-block .result {
  color: var(--accent);
  font-weight: 700;
}

/* ─── EXPLANATION ─────────────────────────────────────────────── */
.slide-explanation {
  font-size: 1rem;
  line-height: 1.6;
  color: var(--navy);
  margin: 20px 0;
}
.slide-explanation strong { color: var(--accent); }

/* ─── EXAMPLE CARDS ──────────────────────────────────────────── */
.examples-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin: 20px 0;
}
@media (min-width: 640px) {
  .examples-row { grid-template-columns: repeat(3, 1fr); }
}
.example-card {
  background: var(--paper);
  border: 1.5px solid var(--accent);
  border-radius: 4px;
  padding: 14px 16px;
}
.example-card .ex-text {
  font-style: italic;
  color: var(--navy);
  font-size: 0.95rem;
  margin-bottom: 8px;
  line-height: 1.4;
}
.example-card .ex-note {
  font-family: var(--font-sans);
  color: var(--muted);
  font-size: 0.78rem;
}

/* ─── WATCH OUT ──────────────────────────────────────────────── */
.watch-out {
  background: var(--cream-deep, #FFF4E8);
  border: 1px solid var(--amber);
  border-radius: 4px;
  padding: 10px 14px;
  margin-top: 16px;
  font-size: 0.88rem;
  line-height: 1.5;
}
.watch-out strong { color: var(--amber); }
.watch-out::before { content: '⚠ '; color: var(--amber); font-weight: 700; }

/* ─── OVERVIEW / SUMMARY ROWS ─────────────────────────────────── */
.overview-row, .summary-row {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border: 1px solid var(--border-soft);
  border-left: 4px solid var(--accent);
  border-radius: 0 4px 4px 0;
  margin-bottom: 8px;
  background: var(--paper);
}
.overview-row .num {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent);
  width: 28px;
  text-align: center;
  flex-shrink: 0;
}
.overview-row .title {
  font-weight: 700;
  color: var(--navy);
  font-size: 0.95rem;
}
.overview-row .ex {
  color: var(--muted);
  font-style: italic;
  font-size: 0.85rem;
  margin-left: auto;
  text-align: right;
}
@media (max-width: 520px) {
  .overview-row { flex-direction: column; align-items: flex-start; gap: 4px; }
  .overview-row .ex { margin-left: 0; text-align: left; }
  .overview-row .num { width: auto; }
}

/* ─── COMPARISON PANELS ───────────────────────────────────────── */
.panel-pair {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}
@media (min-width: 640px) {
  .panel-pair { grid-template-columns: 1fr 1fr; }
}
.panel {
  background: var(--paper);
  border: 1.5px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
}
.panel-head {
  padding: 12px 16px;
  font-family: var(--font-sans);
  letter-spacing: 2px;
  font-weight: 700;
  font-size: 0.78rem;
  text-transform: uppercase;
  color: white;
}
.panel-head.green { background: var(--green); }
.panel-head.amber { background: var(--accent); }
.panel-head.red { background: var(--red); }
.panel-body { padding: 14px 16px; }
.panel-body .ex {
  padding: 10px 0;
  border-bottom: 1px solid var(--border-soft);
  font-size: 0.9rem;
}
.panel-body .ex:last-child { border-bottom: none; }
.panel-body .ex .sent { font-style: italic; color: var(--navy); margin-bottom: 4px; }
.panel-body .ex .note { color: var(--muted); font-size: 0.82rem; }

/* ─── FCE TRAPS GRID (row format) ────────────────────────────── */
.trap-row {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 8px;
  align-items: center;
  margin-bottom: 10px;
  font-size: 0.88rem;
}
.trap-wrong {
  background: rgba(192,57,43,.08);
  border: 1px solid var(--red);
  padding: 8px 12px;
  border-radius: 4px;
  color: var(--red);
  text-decoration: line-through;
}
.trap-wrong::before { content: '✗ '; text-decoration: none; font-weight: 700; }
.trap-arrow { color: var(--muted); font-size: 1rem; }
.trap-right {
  background: rgba(39,174,96,.08);
  border: 1px solid var(--green);
  padding: 8px 12px;
  border-radius: 4px;
  color: var(--green);
}
.trap-right::before { content: '✓ '; font-weight: 700; }
.trap-note {
  grid-column: 1 / -1;
  font-size: 0.78rem;
  color: var(--muted);
  font-style: italic;
  padding: 2px 4px 6px;
}
@media (max-width: 520px) {
  .trap-row { grid-template-columns: 1fr; }
  .trap-arrow { display: none; }
}

/* ─── SUMMARY SLIDE (dark) ───────────────────────────────────── */
.slide.summary-slide .slide-card {
  background: var(--navy-deep);
  color: white;
  padding: 40px 32px;
}
.slide.summary-slide h2 {
  color: white;
  font-size: 2rem;
  margin-bottom: 24px;
}
.summary-row {
  background: rgba(255,255,255,0.04);
  border-color: rgba(255,255,255,0.1);
  border-left-color: var(--accent);
  color: white;
  align-items: flex-start;
  flex-direction: column;
  gap: 6px;
  padding: 14px 16px;
}
.summary-row .label {
  color: var(--accent);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.5px;
}
.summary-row .form {
  font-family: var(--font-serif);
  font-size: 0.88rem;
  color: #D0D8E4;
}
.summary-row .ex {
  color: #9AA8BE;
  font-style: italic;
  font-size: 0.85rem;
  margin-left: 0;
}

/* ─── TWO-UP EXAMPLE PAIRS ───────────────────────────────────── */
.compare-pair {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin: 16px 0;
}
@media (min-width: 640px) {
  .compare-pair { grid-template-columns: 1fr 1fr; }
}
.compare-pair .side {
  background: var(--paper);
  border: 1.5px solid var(--border);
  border-radius: 4px;
  padding: 14px 16px;
}
.compare-pair .tag {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  font-weight: 700;
  margin-bottom: 6px;
}
.compare-pair .tag.green { color: var(--green); }
.compare-pair .tag.amber { color: var(--accent); }
.compare-pair .sent {
  font-style: italic;
  color: var(--navy);
  font-size: 0.95rem;
  margin-bottom: 4px;
}
.compare-pair .note {
  color: var(--muted);
  font-size: 0.82rem;
}

/* ─── MODIFIERS LIST (Ch2 slide 8) ───────────────────────────── */
.mod-list { display: flex; flex-direction: column; gap: 6px; }
.mod-row {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 10px;
  padding: 10px 12px;
  background: var(--paper);
  border: 1px solid var(--border-soft);
  border-radius: 4px;
  font-size: 0.88rem;
}
.mod-row .word { font-weight: 700; }
.mod-row .word.red { color: var(--red); }
.mod-row .word.green { color: var(--green); }
.mod-row .example { color: var(--muted); font-style: italic; }

/* ── Chapter subtitle ── */
.chapter-subtitle {
  font-family: var(--font-sans);
  font-size: .85rem;
  color: var(--muted);
  margin: 2px 0 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--hairline);
}

/* ─── MOBILE SLIDE HEIGHT ────────────────────────────────────────── */
@media (max-width: 520px) {
  .slide-card { min-height: 50vh; padding: 22px 18px; }
  .slide-header h2 { font-size: 1.4rem; }
  .overview-label { font-size: .78rem; min-width: 80px !important; }
}

/* ─── SLIDE DECK CONTAINER ───────────────────────────────────────── */
.slide-deck {
  padding: 0 0 100px;  /* bottom clearance for fixed nav bar */
}
@media (max-width: 520px) {
  .slide-deck { padding: 0 0 90px; }
  .examples-row .example-card { padding: 10px 12px; }
  .trap-row { font-size: .82rem; }
}

/* ══════════════════════════════════════════════════════════════════
   DARK MODE — DEFINITIVE OVERRIDES (Batch 21)
   Strategy: every text-bearing element under .slide-card gets explicit
   light color. Bold/strong tags get explicit color. No exceptions.
   ══════════════════════════════════════════════════════════════════ */

/* Slide card — dark background, light text by default */
body.dark .slide-card {
  background: #1A2230 !important;
  color: #F0F0F0 !important;
  border-top-color: var(--amber);
}
body.dark .summary-slide .slide-card { background: #0D1520 !important; }
body.dark .slide.title-slide .slide-card { background: #050810 !important; color: #FFFFFF !important; }

/* Every direct text element inside slide-card → light */
body.dark .slide-card *:not(a) {
  color: inherit;
}

/* But these specific elements need explicit colors */
body.dark .slide-card,
body.dark .slide-card p,
body.dark .slide-card div,
body.dark .slide-card span,
body.dark .slide-card li,
body.dark .slide-card td,
body.dark .slide-card h1,
body.dark .slide-card h2,
body.dark .slide-card h3,
body.dark .slide-card h4 { color: #F0F0F0 !important; }

/* Headings */
body.dark .slide-card .slide-header h2 { color: #FFFFFF !important; }
body.dark .slide-card .slide-sub        { color: #C8D4E0 !important; }
body.dark .slide-card .slide-explanation { color: #E0E8F0 !important; }

/* Bold/strong/em tags — keep amber for emphasis or white */
body.dark .slide-card strong,
body.dark .slide-card b { color: #FFE4A0 !important; }
body.dark .slide-card em,
body.dark .slide-card i { color: #C8D4E0 !important; }

/* Overview rows */
body.dark .slide-card .overview-row,
body.dark .slide-card .summary-row {
  background: rgba(255,255,255,.06) !important;
  border-color: rgba(255,255,255,.12) !important;
  border-left-color: var(--amber) !important;
}
body.dark .slide-card .overview-label   { color: #FFFFFF !important; font-weight: 700; }
body.dark .slide-card .overview-desc    { color: #E0E8F0 !important; }
body.dark .slide-card .overview-row .title { color: #FFFFFF !important; }
body.dark .slide-card .overview-row .ex    { color: #B8C8D8 !important; }
body.dark .slide-card .overview-row .num   { color: var(--amber) !important; }

/* Summary rows */
body.dark .slide-card .summary-row .label { color: var(--amber) !important; }
body.dark .slide-card .summary-row .form  { color: #FFFFFF !important; }
body.dark .slide-card .summary-row .ex    { color: #C8D4E0 !important; }

/* Panel pairs */
body.dark .slide-card .panel {
  background: rgba(255,255,255,.05) !important;
  border-color: rgba(255,255,255,.15) !important;
}
body.dark .slide-card .panel-head        { color: #FFFFFF !important; }
body.dark .slide-card .panel-head.green  { background: #1a4a28 !important; color: #A0E8B0 !important; }
body.dark .slide-card .panel-head.red    { background: #4a1a1a !important; color: #F0A0A0 !important; }
body.dark .slide-card .panel-body .ex .sent { color: #F0F0F0 !important; font-style: italic; }
body.dark .slide-card .panel-body .ex .note { color: #98A8B8 !important; }

/* Example cards */
body.dark .slide-card .example-card {
  background: rgba(255,255,255,.06) !important;
  border-color: rgba(201,160,80,.5) !important;
}
body.dark .slide-card .example-card .ex-text { color: #FFFFFF !important; }
body.dark .slide-card .example-card .ex-note { color: #B8C8D8 !important; }

/* Formula blocks */
body.dark .slide-card .formula-block {
  background: rgba(255,255,255,.08) !important;
  color: #FFFFFF !important;
  border-color: rgba(255,255,255,.2) !important;
}
body.dark .slide-card .formula-block .arrow  { color: var(--amber) !important; }
body.dark .slide-card .formula-block .result { color: #4CAF82 !important; }

/* Trap rows */
body.dark .slide-card .trap-row { border-bottom-color: rgba(255,255,255,.08) !important; }
body.dark .slide-card .trap-wrong { background: rgba(192,57,43,.25) !important; color: #FFB0A0 !important; }
body.dark .slide-card .trap-right { background: rgba(39,174,96,.25) !important; color: #A0E8B0 !important; }
body.dark .slide-card .trap-arrow { color: var(--amber) !important; }
body.dark .slide-card .trap-note  { color: #98A8B8 !important; }

/* Watch-out boxes */
body.dark .slide-card .watch-out {
  background: rgba(201,160,80,.18) !important;
  border-color: var(--amber) !important;
  color: #FFE4A0 !important;
}
body.dark .slide-card .watch-out strong { color: var(--amber) !important; }
body.dark .slide-card .watch-out em     { color: #FFD080 !important; }

/* Compare pair */
body.dark .slide-card .compare-pair .side {
  background: rgba(255,255,255,.06) !important;
  border-color: rgba(255,255,255,.15) !important;
  color: #F0F0F0 !important;
}

/* Mod rows */
body.dark .slide-card .mod-row {
  background: rgba(255,255,255,.06) !important;
  border-color: rgba(255,255,255,.12) !important;
  color: #F0F0F0 !important;
}

/* Preserve dark text on amber CTA buttons (intentional design) */
body.dark .slide-card a[style*="background:var(--amber)"],
body.dark .slide-card a[style*="background: var(--amber)"],
body.dark a[style*="background:var(--amber)"],
body.dark a[style*="background: var(--amber)"],
body.dark button[style*="background:var(--amber)"],
body.dark .lc-cta-btn {
  color: #1A1A1A !important;
  background: var(--amber) !important;
}

/* Header / chapter meta in dark */
body.dark .chapter-num      { color: var(--amber) !important; }
body.dark .chapter-subtitle { color: #B8C8D8 !important; }
body.dark .breadcrumb       { color: #98A8B8 !important; }
body.dark .breadcrumb a     { color: var(--teal) !important; }
body.dark .breadcrumb strong { color: #FFFFFF !important; }

/* Deck nav buttons (Prev/Next) */
body.dark .deck-btn {
  background: rgba(255,255,255,.08) !important;
  color: #F0F0F0 !important;
  border-color: rgba(255,255,255,.2) !important;
}
body.dark .deck-btn:hover { background: rgba(255,255,255,.15) !important; }
body.dark .deck-btn:disabled { opacity: 0.4; color: #808080 !important; }
body.dark .counter { color: #C8D4E0 !important; }

/* Lesson complete banner — keep amber bg, dark text */
body.dark .lc-banner {
  background: var(--amber) !important;
  color: #1A1A1A !important;
}
body.dark .lc-banner * { color: #1A1A1A !important; }