/* ==========================================================================
   КОД ОПОРУ (shionika.academy) — Sunlit Book & Studio Design System
   Authentic palette & typography from E:\IT-курси ("ШІ на практиці")
   ========================================================================== */

:root {
  --paper: #FBF8F2;
  --parchment: #F3EDE0;
  --parchment-deep: #EAE1CE;
  --sheet: #FFFFFF;
  --ink: #193342;
  --ink-soft: #2C4858;
  --muted: #536772;
  --teal: #126D76;
  --teal-hover: #0D565E;
  --teal-tint: #E8F2F3;
  --brick: #B45343;
  --brick-tint: #F9ECE9;
  --green: #527842;
  --green-tint: #EDF4EA;
  --border: #DDD4C3;
  --border-strong: #C6B9A3;
  --shadow-sheet: 0 14px 36px -12px rgba(25, 51, 66, 0.09), 0 2px 6px rgba(25, 51, 66, 0.04);
  --shadow-book: 0 24px 48px -12px rgba(17, 36, 48, 0.24), -6px 0 14px rgba(17, 36, 48, 0.12);
  --font-serif: 'Newsreader', Georgia, 'Times New Roman', serif;
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', Consolas, 'Courier New', monospace;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
}

*, *::before, *::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

body {
  margin: 0;
  background-color: var(--paper);
  background-image:
    radial-gradient(circle at 15% 0%, rgba(18, 109, 118, 0.045), transparent 42%),
    radial-gradient(circle at 88% 8%, rgba(180, 83, 67, 0.045), transparent 38%);
  color: var(--ink);
  overflow-x: hidden;
}

a {
  color: var(--teal);
  text-decoration: none;
  transition: color 0.15s ease, background-color 0.15s ease, border-color 0.15s ease;
}

a:hover {
  color: var(--teal-hover);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

.container {
  width: min(100% - 40px, 1280px);
  margin-inline: auto;
}

/* --- Top Studio Header --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(251, 248, 242, 0.94);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  min-height: 74px;
}

.brand-mark {
  display: flex;
  align-items: center;
  gap: 13px;
  color: var(--ink);
  text-decoration: none;
}

.brand-spine {
  width: 40px;
  height: 44px;
  border-radius: 6px 9px 9px 6px;
  background: var(--teal);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: 0.03em;
  box-shadow: inset 4px 0 0 rgba(0, 0, 0, 0.18), 0 4px 10px rgba(18, 109, 118, 0.2);
  flex-shrink: 0;
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: 16.5px;
  letter-spacing: 0.04em;
  color: var(--ink);
  line-height: 1.15;
}

.brand-sub {
  font-size: 12.5px;
  color: var(--muted);
  line-height: 1.25;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.nav-link {
  padding: 8px 13px;
  border-radius: var(--radius-sm);
  font-size: 14.5px;
  font-weight: 600;
  color: var(--ink-soft);
}

.nav-link:hover {
  background: var(--parchment);
  color: var(--ink);
}

.nav-link.active {
  background: var(--teal-tint);
  color: var(--teal);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.lang-switch {
  display: inline-flex;
  background: var(--parchment);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 2px;
}

.lang-pill {
  padding: 5px 10px;
  font-size: 12.5px;
  font-weight: 700;
  border-radius: 4px;
  color: var(--muted);
}

.lang-pill.active {
  background: var(--sheet);
  color: var(--ink);
  box-shadow: 0 1px 3px rgba(25, 51, 66, 0.08);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 18px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 14.5px;
  font-weight: 600;
  line-height: 1.25;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.16s ease;
  text-decoration: none;
}

.btn-primary {
  background: var(--teal);
  color: #fff;
  box-shadow: 0 2px 6px rgba(18, 109, 118, 0.18);
}

.btn-primary:hover {
  background: var(--teal-hover);
  color: #fff;
}

.btn-secondary {
  background: var(--sheet);
  color: var(--ink);
  border-color: var(--border-strong);
}

.btn-secondary:hover {
  background: var(--parchment);
  color: var(--ink);
}

.btn-brick {
  background: var(--brick);
  color: #fff;
}

.btn-brick:hover {
  background: #9B4334;
  color: #fff;
}

.btn-sm {
  padding: 8px 13px;
  font-size: 13.5px;
}

/* --- Hero Spread --- */
.hero-spread {
  padding: 44px 0 52px;
  border-bottom: 1px solid var(--border);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.12fr) minmax(0, 0.88fr);
  gap: 44px;
  align-items: start;
}

.book-kicker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px;
  background: var(--parchment);
  border: 1px solid var(--border);
  border-left: 3px solid var(--teal);
  border-radius: 4px;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-soft);
  margin-bottom: 18px;
}

.hero-title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(34px, 4.3vw, 54px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin: 0 0 18px;
}

.hero-title span.sub-line {
  display: block;
  font-weight: 400;
  font-style: italic;
  color: var(--teal);
  margin-top: 6px;
}

.hero-lead {
  font-size: 18px;
  line-height: 1.62;
  color: var(--ink-soft);
  max-width: 62ch;
  margin: 0 0 26px;
}

.hero-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 30px;
}

.pilot-facts-bar {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 18px;
  box-shadow: var(--shadow-sheet);
}

.fact-cell {
  padding: 10px 12px;
  border-left: 3px solid var(--teal);
  background: var(--paper);
  border-radius: 4px;
}

.fact-cell.brick {
  border-left-color: var(--brick);
}

.fact-num {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 22px;
  color: var(--ink);
  line-height: 1.15;
  margin-bottom: 3px;
}

.fact-label {
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.38;
}

/* --- Hero Interactive Book & Edition Showcase --- */
.studio-showcase {
  background: var(--parchment);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  padding: 22px;
  box-shadow: var(--shadow-sheet);
}

.edition-tabs {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 6px;
  margin-bottom: 18px;
}

.edition-tab {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 9px 11px;
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-soft);
  text-align: left;
  cursor: pointer;
  transition: all 0.15s ease;
}

.edition-tab:hover {
  background: var(--sheet);
}

.edition-tab.active {
  background: var(--teal);
  color: #fff;
  border-color: var(--teal);
}

.edition-panel {
  display: none;
}

.edition-panel.active {
  display: block;
}

.book-stage {
  display: grid;
  grid-template-columns: 205px 1fr;
  gap: 20px;
  align-items: center;
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 18px;
}

.book-cover-3d {
  position: relative;
  border-radius: 4px 8px 8px 4px;
  overflow: hidden;
  box-shadow: var(--shadow-book);
  border: 1px solid rgba(25, 51, 66, 0.15);
  background: var(--paper);
}

.book-cover-3d img {
  width: 100%;
  height: auto;
  display: block;
}

.book-meta h3 {
  font-family: var(--font-serif);
  font-size: 21px;
  line-height: 1.22;
  margin: 0 0 8px;
  color: var(--ink);
}

.book-meta p {
  font-size: 14px;
  color: var(--muted);
  margin: 0 0 12px;
  line-height: 1.5;
}

.book-specs {
  list-style: none;
  padding: 0;
  margin: 0 0 16px;
  font-size: 13.5px;
}

.book-specs li {
  padding: 4px 0;
  border-bottom: 1px dashed var(--border);
  display: flex;
  justify-content: space-between;
  gap: 8px;
}

/* --- Section Headings --- */
.section-block {
  padding: 56px 0;
  border-bottom: 1px solid var(--border);
}

.section-block.alt-bg {
  background: var(--parchment);
}

.section-header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}

.section-header-left {
  max-width: 720px;
}

.section-index {
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 600;
  color: var(--teal);
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(28px, 3.2vw, 40px);
  font-weight: 600;
  line-height: 1.14;
  color: var(--ink);
  margin: 0 0 10px;
}

.section-desc {
  font-size: 16.5px;
  color: var(--muted);
  margin: 0;
  line-height: 1.55;
}

/* --- Interactive Student Portfolio Workbench (3 Projects) --- */
.workbench-shell {
  background: var(--sheet);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sheet);
  overflow: hidden;
}

.workbench-nav {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  background: var(--parchment);
  border-bottom: 1px solid var(--border);
}

.wb-tab {
  padding: 16px 20px;
  border: 0;
  border-right: 1px solid var(--border);
  border-bottom: 3px solid transparent;
  background: transparent;
  text-align: left;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: background 0.15s ease;
}

.wb-tab:last-child {
  border-right: 0;
}

.wb-tab:hover {
  background: rgba(255, 255, 255, 0.55);
}

.wb-tab.active {
  background: var(--sheet);
  border-bottom-color: var(--teal);
}

.wb-tab-lesson {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--teal);
  font-weight: 600;
  display: block;
  margin-bottom: 3px;
}

.wb-tab-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
  display: block;
}

.wb-tab-sub {
  font-size: 13px;
  color: var(--muted);
  display: block;
  margin-top: 2px;
}

.wb-pane {
  display: none;
  padding: 28px;
}

.wb-pane.active {
  display: block;
}

.wb-split {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1.05fr);
  gap: 32px;
  align-items: start;
}

.wb-split > *,
.hero-grid > *,
.reader-layout > *,
.budget-calc-grid > *,
.parts-grid > * {
  min-width: 0;
}

.wb-info h3 {
  font-family: var(--font-serif);
  font-size: 26px;
  margin: 0 0 10px;
  color: var(--ink);
}

.wb-info p {
  font-size: 15.5px;
  color: var(--ink-soft);
  margin: 0 0 14px;
}

.wb-check-list {
  list-style: none;
  padding: 0;
  margin: 0 0 20px;
}

.wb-check-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 7px 0;
  border-bottom: 1px solid var(--parchment);
  font-size: 14.5px;
}

.sub-mode-bar {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 6px;
  background: var(--parchment);
  padding: 4px;
  border-radius: var(--radius-sm);
  margin-bottom: 14px;
}

.sub-mode-btn {
  border: 0;
  background: transparent;
  padding: 6px 12px;
  border-radius: 4px;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-soft);
  cursor: pointer;
}

.sub-mode-btn.active {
  background: var(--sheet);
  color: var(--teal);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}

/* Browser Mockup for Olena's Personal Site */
.browser-frame {
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  background: #fff;
  overflow: hidden;
  box-shadow: 0 10px 28px rgba(25, 51, 66, 0.08);
}

.browser-chrome {
  background: var(--parchment);
  border-bottom: 1px solid var(--border);
  padding: 9px 14px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.browser-dots {
  display: flex;
  gap: 6px;
}

.browser-dots span {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border-strong);
}

.browser-url {
  flex: 1;
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 4px 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-soft);
}

.olena-live-canvas {
  padding: 24px 28px;
  color: #20362f;
  background: #ffffff;
  font-family: "Segoe UI", var(--font-sans);
}

.olena-live-canvas.narrow-view {
  max-width: 360px;
  margin: 14px auto;
  border: 1px solid #ccd8d1;
  border-radius: 8px;
}

.olena-nav {
  display: flex;
  gap: 20px;
  padding-bottom: 14px;
  border-bottom: 1px solid #ccd8d1;
  margin-bottom: 20px;
  font-size: 15px;
}

.olena-nav a {
  color: #174f87;
  text-decoration: underline;
  text-underline-offset: 4px;
}

.olena-h1 {
  font-family: Georgia, serif;
  font-size: 36px;
  margin: 0 0 12px;
  color: #20362f;
}

.olena-intro {
  font-size: 17px;
  margin: 0 0 18px;
  color: #20362f;
}

.olena-projects {
  list-style: none;
  padding: 0;
  margin: 12px 0;
}

.olena-projects li {
  padding: 10px 0;
  border-top: 1px solid #ccd8d1;
}

.olena-projects h4 {
  margin: 0 0 4px;
  font-size: 17px;
}

.olena-projects p {
  margin: 0;
  font-size: 14.5px;
}

.olena-contact {
  background: #edf5ef;
  padding: 14px 16px;
  margin-top: 14px;
  font-size: 14px;
}

/* Interactive My Day PWA Phone Simulator */
.phone-simulator {
  max-width: 390px;
  margin: 0 auto;
  background: #edf5ef;
  border: 8px solid #193342;
  border-radius: 26px;
  padding: 18px;
  box-shadow: 0 18px 36px rgba(25, 51, 66, 0.16);
}

.myday-card {
  background: #ffffff;
  border-top: 6px solid #20362f;
  padding: 22px;
  color: #20362f;
}

.myday-h1 {
  font-family: Georgia, serif;
  font-size: 32px;
  margin: 0 0 6px;
}

.myday-intro {
  color: #52645d;
  font-size: 15px;
  margin: 0 0 14px;
}

.myday-progress {
  font-size: 21px;
  font-weight: 700;
  margin: 0 0 14px;
  color: #20362f;
}

.myday-task {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 13px 0;
  border-bottom: 1px solid #ccd8d1;
  cursor: pointer;
  font-size: 16.5px;
}

.myday-task input[type="checkbox"] {
  width: 22px;
  height: 22px;
  accent-color: #174f87;
  cursor: pointer;
}

.myday-task input[type="checkbox"]:checked + span {
  text-decoration: line-through;
  color: #52645d;
}

.myday-btn {
  margin-top: 16px;
  border: 0;
  background: #174f87;
  color: #ffffff;
  font-weight: 600;
  font-size: 15.5px;
  padding: 11px 16px;
  cursor: pointer;
  width: 100%;
}

.myday-btn:hover {
  background: #113e6a;
}

.myday-status {
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px solid #ccd8d1;
  font-size: 13.5px;
  color: #52645d;
}

/* Carousel Interactive Viewer */
.carousel-viewer {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
}

.carousel-main-stage {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 20px;
  align-items: center;
}

.carousel-active-img {
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  overflow: hidden;
  background: #fff;
}

.carousel-thumbs {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

.carousel-thumb {
  width: 56px;
  height: 56px;
  border: 2px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  cursor: pointer;
  padding: 0;
  background: #fff;
}

.carousel-thumb.active {
  border-color: var(--teal);
}

/* --- 10 Parts Bookshelf Grid --- */
.parts-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 22px;
}

.part-card {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-top: 5px solid var(--part-color, var(--teal));
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sheet);
  display: flex;
  flex-direction: column;
}

.part-card-top {
  display: grid;
  grid-template-columns: 165px 1fr;
  gap: 18px;
  padding: 20px;
  border-bottom: 1px solid var(--parchment);
}

.part-art {
  width: 100%;
  height: 155px;
  object-fit: cover;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.part-badge-row {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  color: var(--part-color, var(--teal));
  margin-bottom: 6px;
}

.part-title {
  font-family: var(--font-serif);
  font-size: 22px;
  line-height: 1.2;
  margin: 0 0 6px;
  color: var(--ink);
}

.part-sub {
  font-size: 14px;
  color: var(--muted);
  margin: 0 0 10px;
}

.part-outcomes {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 13.5px;
  color: var(--ink-soft);
}

.part-outcomes li {
  position: relative;
  padding-left: 14px;
  margin-bottom: 3px;
}

.part-outcomes li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--part-color, var(--teal));
  font-weight: 700;
}

.part-lessons-list {
  padding: 14px 20px;
  background: var(--paper);
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 1;
}

.lesson-row-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 8px 11px;
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--ink);
  font-size: 14px;
}

.lesson-row-link:hover {
  border-color: var(--part-color, var(--teal));
  background: var(--teal-tint);
}

.lesson-num-pill {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  padding: 2px 7px;
  border-radius: 4px;
  background: var(--parchment);
  color: var(--part-color, var(--teal));
  flex-shrink: 0;
}

.lesson-row-title {
  flex: 1;
  font-weight: 600;
}

.lesson-row-time {
  font-size: 12px;
  color: var(--muted);
  flex-shrink: 0;
}

/* --- Three AI Tool Families --- */
.tools-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
}

.tool-card {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 22px;
  box-shadow: var(--shadow-sheet);
  display: flex;
  flex-direction: column;
}

.tool-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--teal);
  font-weight: 600;
  margin-bottom: 6px;
}

.tool-card h3 {
  font-family: var(--font-serif);
  font-size: 23px;
  margin: 0 0 8px;
}

.tool-shot {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
  margin: 12px 0;
  background: var(--paper);
}

.tool-shot img {
  width: 100%;
  height: 165px;
  object-fit: cover;
  object-position: top left;
}

.cmd-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: auto;
  padding-top: 12px;
}

.cmd-chip {
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 3px 8px;
  background: var(--parchment);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--ink);
}

/* --- Book Lesson Reader (/lesson/L01..L33) --- */
.reader-layout {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 32px;
  padding: 36px 0 64px;
  align-items: start;
}

.reader-sidebar {
  position: sticky;
  top: 92px;
  max-height: calc(100vh - 110px);
  overflow-y: auto;
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
  box-shadow: var(--shadow-sheet);
}

.toc-part-group {
  margin-bottom: 14px;
}

.toc-part-title {
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
  padding: 4px 6px;
  border-left: 3px solid var(--part-color, var(--teal));
  margin-bottom: 5px;
}

.toc-lesson-link {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 8px;
  border-radius: 4px;
  font-size: 13.5px;
  color: var(--ink-soft);
}

.toc-lesson-link:hover {
  background: var(--parchment);
}

.toc-lesson-link.active {
  background: var(--teal);
  color: #fff;
  font-weight: 600;
}

.book-sheet {
  background: var(--sheet);
  border: 1px solid var(--border-strong);
  border-top: 6px solid var(--lesson-color, var(--teal));
  border-radius: var(--radius-lg);
  padding: clamp(24px, 4vw, 52px);
  box-shadow: var(--shadow-sheet);
  max-width: 880px;
}

.lesson-header-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 22px;
}

.lesson-part-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13.5px;
  font-weight: 700;
  color: var(--lesson-color, var(--teal));
}

.lesson-h1 {
  font-family: var(--font-serif);
  font-size: clamp(30px, 3.6vw, 42px);
  line-height: 1.15;
  margin: 0 0 18px;
  color: var(--ink);
}

.lesson-num-badge {
  display: inline-block;
  background: var(--lesson-color, var(--teal));
  color: #fff;
  font-family: var(--font-sans);
  font-size: 0.65em;
  padding: 3px 11px;
  border-radius: 6px;
  vertical-align: middle;
  margin-right: 10px;
}

.scenario-passport {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 28px;
}

.passport-item strong {
  display: block;
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 4px;
}

.passport-item span {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.book-p {
  font-size: 17.5px;
  line-height: 1.68;
  color: var(--ink);
  margin: 0 0 16px;
  max-width: 68ch;
}

.book-h2 {
  font-family: var(--font-serif);
  font-size: 25px;
  line-height: 1.25;
  color: var(--ink);
  margin: 32px 0 12px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--parchment-deep);
}

.book-h3 {
  font-family: var(--font-serif);
  font-size: 20px;
  color: var(--ink);
  margin: 22px 0 8px;
}

.book-list, .book-olist {
  font-size: 17px;
  line-height: 1.65;
  margin: 0 0 18px;
  padding-left: 24px;
  max-width: 66ch;
}

.book-list li, .book-olist li {
  margin-bottom: 8px;
}

.inline-code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--parchment);
  padding: 2px 6px;
  border-radius: 4px;
  color: var(--ink);
}

.source-ref {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--teal);
  font-weight: 600;
  margin-left: 3px;
}

/* Callouts */
.book-callout {
  background: var(--paper);
  border: 1px solid var(--border);
  border-left: 4px solid var(--callout-color, var(--teal));
  border-radius: 6px;
  padding: 15px 18px;
  margin: 20px 0;
}

.callout-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 6px;
}

.callout-badge {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font-size: 13.5px;
  font-weight: 700;
  color: var(--callout-color, var(--teal));
}

.callout-body {
  font-size: 16.5px;
  line-height: 1.6;
  color: var(--ink);
}

/* Code blocks */
.book-code-wrap {
  margin: 18px 0;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: #F3F5F6;
}

.book-code-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 12px;
  background: var(--parchment);
  border-bottom: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--muted);
}

.book-code {
  margin: 0;
  padding: 14px 16px;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.55;
  color: var(--ink);
}

.copy-btn {
  border: 1px solid var(--border-strong);
  background: var(--sheet);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 4px;
  cursor: pointer;
}

.copy-btn:hover {
  background: var(--teal);
  color: #fff;
  border-color: var(--teal);
}

/* Book Tables */
.book-table-wrap {
  overflow-x: auto;
  margin: 20px 0;
}

.book-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
  border: 1px solid var(--border);
}

.book-table th {
  background: var(--table-head, var(--teal));
  color: #fff;
  text-align: left;
  padding: 10px 13px;
  font-weight: 600;
}

.book-table td {
  padding: 10px 13px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.book-table tbody tr:nth-child(even) {
  background: var(--paper);
}

/* Visual Plates & Screenshots */
.book-plate, .book-shot {
  margin: 24px 0;
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 18px;
}

.plate-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 15px;
  color: var(--plate-accent, var(--teal));
  margin-bottom: 14px;
}

.vis-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 12px;
}

.vis-item {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-top: 3px solid var(--plate-accent, var(--teal));
  border-radius: var(--radius-sm);
  padding: 12px 14px;
}

.vis-item-top {
  display: flex;
  align-items: center;
  gap: 7px;
  margin-bottom: 6px;
}

.vis-step-num {
  font-family: var(--font-mono);
  font-size: 11.5px;
  font-weight: 700;
  color: var(--plate-accent, var(--teal));
  background: var(--parchment);
  padding: 1px 6px;
  border-radius: 3px;
}

.vis-item-title {
  font-size: 14.5px;
  color: var(--ink);
}

.vis-item-body {
  margin: 0;
  font-size: 13.5px;
  color: var(--muted);
  line-height: 1.45;
}

.plate-caption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--muted);
}

.plate-two-cols, .plate-browser-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  align-items: start;
}

.plate-img-card {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px;
}

.plate-img-tag {
  font-size: 12.5px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 8px;
}

.plate-carousel-strip {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 10px;
}

.plate-carousel-item {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 6px;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 11.5px;
  color: var(--muted);
}

.plate-app-row {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 20px;
  align-items: center;
}

.plate-phone-shot {
  border: 1px solid var(--border);
  border-radius: 8px;
}

.timeline-plate {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px;
}

.tl-row {
  display: grid;
  grid-template-columns: 90px 1fr;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.tl-label {
  font-size: 12.5px;
  font-weight: 700;
  color: var(--muted);
}

.tl-track {
  display: flex;
  gap: 3px;
  background: var(--parchment);
  border-radius: 4px;
  padding: 4px;
}

.tl-chip, .tl-seg {
  color: #fff;
  border-radius: 3px;
  padding: 6px 8px;
  font-size: 12px;
  display: flex;
  flex-direction: column;
}

.tl-summary {
  font-weight: 700;
  font-size: 14px;
  color: var(--ink);
  margin-top: 6px;
}

/* Interactive Answer Key Box */
.selftest-card {
  margin-top: 28px;
  background: var(--parchment);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  padding: 20px;
}

.answer-reveal-box {
  display: none;
  margin-top: 14px;
  background: var(--sheet);
  border-left: 4px solid var(--green);
  padding: 14px 18px;
  border-radius: 4px;
}

.answer-reveal-box.open {
  display: block;
}

/* --- Sponsors Deck & Interactive Budget Calculator --- */
.slides-deck-viewer {
  background: var(--sheet);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  padding: 26px;
  box-shadow: var(--shadow-sheet);
}

.slide-canvas {
  background: var(--paper);
  border: 1px solid var(--border);
  border-top: 6px solid var(--teal);
  border-radius: var(--radius-md);
  padding: 32px;
  min-height: 360px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.budget-calc-grid {
  display: grid;
  grid-template-columns: 360px 1fr;
  gap: 28px;
  align-items: start;
}

.calc-sidebar {
  background: var(--sheet);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  padding: 22px;
  box-shadow: var(--shadow-sheet);
  position: sticky;
  top: 92px;
}

/* --- Footer & SEO Block --- */
.seoq {
  background: var(--parchment);
  border-top: 1px solid var(--border);
  padding: 40px 0;
}

.seoq-inner {
  width: min(100% - 40px, 1280px);
  margin-inline: auto;
}

.seoq h2 {
  font-family: var(--font-serif);
  font-size: 24px;
  margin: 0 0 18px;
}

.seoq-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.seoq-grid article {
  background: var(--sheet);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 16px;
}

.seoq-grid h3 {
  font-size: 15.5px;
  margin: 0 0 8px;
  color: var(--ink);
}

.seoq-grid p {
  font-size: 13.5px;
  color: var(--muted);
  margin: 0;
}

.site-footer {
  background: var(--ink);
  color: #DCE5EA;
  padding: 48px 0 36px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1fr;
  gap: 32px;
  margin-bottom: 32px;
}

.footer-title {
  font-weight: 700;
  font-size: 15px;
  color: #fff;
  margin: 0 0 12px;
}

.footer-links {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 14px;
}

.footer-links li {
  margin-bottom: 8px;
}

.footer-links a {
  color: #B8C8D1;
}

.footer-links a:hover {
  color: #fff;
}

.footer-bottom {
  padding-top: 22px;
  border-top: 1px solid rgba(255, 255, 255, 0.12);
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  font-size: 13px;
  color: #93A8B4;
}

/* --- Responsive Media Queries --- */
@media (max-width: 1024px) {
  .hero-grid,
  .wb-split,
  .parts-grid,
  .tools-grid,
  .reader-layout,
  .budget-calc-grid,
  .seoq-grid,
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .reader-sidebar,
  .calc-sidebar {
    position: static;
    max-height: none;
  }
}

@media (max-width: 680px) {
  .container {
    width: calc(100% - 28px);
  }
  .header-inner {
    flex-wrap: wrap;
    padding: 10px 0;
  }
  .main-nav {
    order: 3;
    width: 100%;
    overflow-x: auto;
    flex-wrap: nowrap;
    padding-bottom: 4px;
  }
  .nav-link {
    white-space: nowrap;
  }
  .pilot-facts-bar,
  .edition-tabs,
  .book-stage,
  .workbench-nav,
  .part-card-top,
  .carousel-main-stage,
  .plate-two-cols,
  .plate-browser-grid,
  .plate-app-row,
  .scenario-passport {
    grid-template-columns: 1fr;
  }
  .plate-carousel-strip {
    grid-template-columns: repeat(2, 1fr);
  }
}