/* ─── Generate workspace + PDF preview (split layout) ─────────────────────── */
.generate-workspace {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  width: 100%;
  max-width: 42rem;
  margin-left: auto;
  margin-right: auto;
  gap: 0;
}

.gen-surface {
  border-color: rgba(255, 255, 255, 0.06);
  box-shadow:
    0 0 0 1px rgba(255, 255, 255, 0.03) inset,
    0 18px 40px -16px rgba(0, 0, 0, 0.5);
}

.gen-surface-head {
  letter-spacing: 0.02em;
}

.generate-workspace.preview-mode {
  max-width: none;
  margin-left: 0;
  margin-right: 0;
  width: 100%;
  gap: 0.65rem 1rem;
}

.generate-workspace.preview-mode {
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

@media (min-width: 1024px) {
  .generate-workspace.preview-mode {
    display: grid;
    grid-template-columns: minmax(0, var(--left-col-width)) minmax(0, 1fr);
    grid-template-rows: minmax(0, 1fr);
    align-items: start;
  }
}

/* PDF column */
.pdf-preview-stack {
  min-width: 0;
}

.pdf-tab-bar-wrap {
  display: none;
  align-items: center;
  width: auto;
  max-width: 100%;
  min-width: 0;
}

.pdf-tab-bar-wrap[hidden] {
  display: none !important;
}

/* Two-column grid: [back-btn auto] [sliders centered in 1fr].
   Ranking button is position:absolute so it can't disturb the grid. */
body.preview-mode-active #pdf-tab-bar-wrap:not([hidden]) {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  position: relative;
  width: 100%;
  max-width: 100%;
  min-width: 0;
  opacity: 1;
}

body.preview-mode-active #pdf-tab-bar-wrap:not([hidden]) > .pdf-tab-primary-clip {
  justify-self: center;
}

/* ─── Ranking area — wrapper carries the absolute position ────────────── */
.ranking-tab-area {
  position: absolute;
  left: calc(2rem + 10%);
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  align-items: center;
  gap: 0.4rem;
  min-width: 0;
  max-width: 40%;
}

/* ─── Ranking button — styled like the back button ────────────────────── */
.pdf-tab-ranking-btn {
  position: static;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.25rem;
  padding: 0.3rem 0.5rem;
  border-radius: 9999px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: rgba(255, 255, 255, 0.05);
  color: rgb(148 163 184);
  font-size: 0.70rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1;
  white-space: nowrap;
  cursor: pointer;
  transition: border-color 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.pdf-tab-ranking-btn svg:not(.hidden) {
  display: block;
  width: 1.12rem;
  height: 1.12rem;
  flex-shrink: 0;
}

.pdf-tab-ranking-btn:hover:not(:disabled) {
  border-color: rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.09);
  color: rgb(226 232 240);
}

.pdf-tab-ranking-btn:active:not(:disabled) {
  background: rgba(255, 255, 255, 0.13);
}

.pdf-tab-ranking-btn[aria-selected="true"] {
  border-color: rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.09);
  color: rgb(226 232 240);
}

.pdf-tab-ranking-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.pdf-tab-ranking-btn--generating {
  opacity: 1;
  cursor: default;
}

.pdf-tab-ranking-btn:focus-visible {
  outline: 2px solid rgba(34, 211, 238, 0.45);
  outline-offset: 2px;
}

/* Tab track sits in the auto centre column, truly centred over the PDF pane */
.pdf-tab-primary-clip {
  display: flex;
  justify-content: center;
  align-items: center;
  min-width: 0;
}

/* ─── Back button (shown in preview tab bar) ─────────────────────────────── */
.pdf-tab-back-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  padding: 0.4rem;
  border-radius: 9999px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: rgba(255, 255, 255, 0.05);
  color: rgb(148 163 184);
  cursor: pointer;
  transition: border-color 0.18s ease, background 0.18s ease, color 0.18s ease;
}

.pdf-tab-back-btn svg {
  display: block;
  width: 1.1rem;
  height: 1.1rem;
  flex-shrink: 0;
  overflow: visible;
  /* Explicit stroke: avoids invisible icon if currentColor chain breaks in flex/grid */
  stroke: rgb(148 163 184);
  stroke-width: 2px;
  fill: none;
}

.pdf-tab-back-btn:hover {
  border-color: rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.09);
  color: rgb(226 232 240);
}

.pdf-tab-back-btn:hover svg {
  stroke: rgb(226 232 240);
}

.pdf-tab-back-btn:active {
  background: rgba(255, 255, 255, 0.13);
}

.pdf-tab-back-btn:focus-visible {
  outline: 2px solid rgba(34, 211, 238, 0.45);
  outline-offset: 2px;
}

/* Single-row preview control: [ Exercise sheet + 1/2/4-up ] | [ Mark scheme ] */
.pdf-tab-primary-track {
  --pdf-bar-edge: rgba(56, 189, 248, 0.22);
  --pdf-bar-fill-top: rgba(10, 28, 58, 0.82);
  --pdf-bar-fill-bot: rgba(6, 16, 42, 0.88);
  --pdf-sheet-pill: linear-gradient(152deg, rgba(56, 189, 248, 0.38) 0%, rgba(99, 102, 241, 0.24) 50%, rgba(79, 70, 229, 0.16) 100%);
  --pdf-sheet-pill-glow: inset 0 1px 0 rgba(255, 255, 255, 0.22), 0 0 0 1px rgba(56, 189, 248, 0.28), 0 0 32px -5px rgba(56, 189, 248, 0.32);
  --pdf-answers-pill: linear-gradient(152deg, rgba(52, 211, 153, 0.45) 0%, rgba(45, 212, 191, 0.28) 50%, rgba(20, 184, 166, 0.18) 100%);
  --pdf-answers-pill-glow: inset 0 1px 0 rgba(255, 255, 255, 0.2), 0 0 0 1px rgba(52, 211, 153, 0.28), 0 0 32px -5px rgba(52, 211, 153, 0.3);
  --pdf-embed-border: rgba(56, 189, 248, 0.25);
  --pdf-embed-bg: linear-gradient(180deg, rgba(6, 24, 52, 0.88) 0%, rgba(4, 14, 36, 0.92) 100%);
  --pdf-embed-inset: inset 0 1px 2px rgba(0, 0, 0, 0.5);

  position: relative;
  display: flex;
  align-items: stretch;
  gap: 0.3rem;
  min-width: 0;
  max-width: 100%;
  width: min(100%, 24rem);
  padding: 0.24rem;
  border-radius: 9999px;
  border: 1px solid var(--pdf-bar-edge);
  background: linear-gradient(180deg, var(--pdf-bar-fill-top) 0%, var(--pdf-bar-fill-bot) 100%);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.1),
    0 0 0 1px rgba(56, 189, 248, 0.1),
    0 8px 28px -6px rgba(0, 0, 0, 0.55),
    0 0 48px -10px rgba(56, 189, 248, 0.2);
  backdrop-filter: blur(18px) saturate(1.15);
  -webkit-backdrop-filter: blur(18px) saturate(1.15);
  transition:
    border-color 0.28s ease,
    box-shadow 0.32s ease;
}

.pdf-tab-primary-track:hover {
  border-color: rgba(56, 189, 248, 0.5);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.14),
    0 0 0 1px rgba(56, 189, 248, 0.18),
    0 8px 32px -6px rgba(0, 0, 0, 0.55),
    0 0 56px -8px rgba(56, 189, 248, 0.35);
}

.pdf-tab-sheet-column,
.pdf-tab-answers-column,
.pdf-tab-layout-column {
  position: relative;
  display: flex;
  align-items: stretch;
  min-width: 0;
}

.pdf-tab-sheet-column {
  flex: 0 0 auto;
  align-items: center;
  padding-left: 0.55rem;
  padding-right: 0.15rem;
  cursor: pointer;
}

.pdf-tab-layout-column {
  flex: 0 0 auto;
  align-items: center;
  padding: 0.15rem 0;
  z-index: 1;
}

.pdf-tab-answers-column {
  flex: 0 0 auto;
  padding-left: 0.15rem;
  padding-right: 0.25rem;
}

/* Single pill that slides between sheet and answers sides.
   JS (syncSidePill) measures getBoundingClientRect() and writes
   --pill-right-inset / --pill-left-inset on the pill element.
   CSS owns left, right, and the asymmetric transition so the
   expanding (leading) edge is faster than the trailing edge. */
.pdf-tab-side-pill {
  position: absolute;
  top: 0;
  bottom: 0;
  border-radius: 9999px;
  pointer-events: none;
  z-index: 0;
  will-change: left, right;
}

.pdf-tab-primary-track[data-side="sheet"] .pdf-tab-side-pill {
  background: var(--pdf-sheet-pill);
  box-shadow: var(--pdf-sheet-pill-glow);
  left: 0;
  right: var(--pill-right-inset, 0px);
  transition:
    left  0.26s cubic-bezier(0.16, 1, 0.3, 1),
    right 0.42s cubic-bezier(0.16, 1, 0.3, 1),
    background 0.32s ease,
    box-shadow 0.32s ease;
}

.pdf-tab-primary-track[data-side="answers"] .pdf-tab-side-pill {
  background: var(--pdf-answers-pill);
  box-shadow: var(--pdf-answers-pill-glow);
  left: var(--pill-left-inset, 0px);
  right: 0;
  transition:
    left  0.42s cubic-bezier(0.16, 1, 0.3, 1),
    right 0.26s cubic-bezier(0.16, 1, 0.3, 1),
    background 0.32s ease,
    box-shadow 0.32s ease;
}

.pdf-tab-sheet-label {
  position: relative;
  z-index: 1;
  flex-shrink: 0;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.015em;
  color: rgb(100 116 139);
  transition: color 0.30s ease, text-shadow 0.30s ease;
  user-select: none;
  cursor: pointer;
  padding: 0.4rem 0 0.4rem 0;
}

.pdf-tab-primary-track[data-side="sheet"] .pdf-tab-sheet-label {
  color: rgb(186 230 253);
  text-shadow: 0 0 16px rgba(56, 189, 248, 0.25);
}

.pdf-tab-primary-track[data-side="answers"] .pdf-tab-sheet-label {
  color: rgb(120 140 165);
}

.pdf-tab-layout-track {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  align-items: stretch;
  flex: 0 0 auto;
  min-width: 0;
  padding: var(--pill-pad);
  gap: 0;
  border-radius: 9999px;
  border: 1px solid var(--pdf-embed-border);
  background: var(--pdf-embed-bg);
  box-shadow: var(--pdf-embed-inset);
}

.pdf-tab-layout-track--embedded {
  min-width: 5.75rem;
  transition:
    opacity 0.30s ease,
    border-color 0.30s ease,
    box-shadow 0.30s ease,
    filter 0.30s ease;
}

.pdf-tab-layout-track--embedded:hover {
  border-color: rgba(56, 189, 248, 0.4);
  box-shadow:
    var(--pdf-embed-inset),
    0 0 18px -4px rgba(56, 189, 248, 0.25);
}

.pdf-tab-primary-track[data-side="answers"] .pdf-tab-layout-track--embedded {
  opacity: 1;
  border-color: rgba(52, 211, 153, 0.22);
}

.pdf-tab-layout-pill {
  position: absolute;
  top: var(--pill-pad);
  bottom: var(--pill-pad);
  left: var(--pill-pad);
  width: calc((100% - var(--pill-gap)) / 3);
  border-radius: 9999px;
  will-change: left;
  transition:
    left 0.32s cubic-bezier(0.16, 1, 0.3, 1),
    background 0.28s ease,
    box-shadow 0.28s ease;
  pointer-events: none;
  z-index: 0;
}

.pdf-tab-layout-track[data-layout="exercise"] .pdf-tab-layout-pill {
  left: var(--pill-pad);
  background: linear-gradient(180deg, rgba(56, 189, 248, 0.42) 0%, rgba(56, 189, 248, 0.2) 100%);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.24),
    0 0 0 1px rgba(125, 211, 252, 0.28),
    0 0 20px -3px rgba(56, 189, 248, 0.45);
}

.pdf-tab-layout-track[data-layout="two-up"] .pdf-tab-layout-pill {
  left: calc(var(--pill-pad) + (100% - var(--pill-gap)) / 3);
  background: linear-gradient(180deg, rgba(251, 191, 36, 0.44) 0%, rgba(245, 158, 11, 0.22) 100%);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.22),
    0 0 0 1px rgba(252, 211, 77, 0.3),
    0 0 20px -3px rgba(251, 191, 36, 0.42);
}

.pdf-tab-layout-track[data-layout="four-up"] .pdf-tab-layout-pill {
  left: calc(var(--pill-pad) + (100% - var(--pill-gap)) * 2 / 3);
  background: linear-gradient(180deg, rgba(167, 139, 250, 0.44) 0%, rgba(139, 92, 246, 0.22) 100%);
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.2),
    0 0 0 1px rgba(196, 181, 253, 0.3),
    0 0 20px -3px rgba(167, 139, 250, 0.42);
}

.pdf-tab-primary-facet {
  position: relative;
  z-index: 1;
  align-self: center;
  border: none;
  border-radius: 9999px;
  padding: 0.4rem 0.8rem;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.015em;
  background: transparent;
  color: rgb(110 200 170);
  cursor: pointer;
  transition: color 0.30s ease, opacity 0.30s ease, text-shadow 0.30s ease;
}

/* Hover glow when sheet label is clickable (answers mode) */
.pdf-tab-primary-track[data-side="answers"] .pdf-tab-sheet-column:hover .pdf-tab-sheet-label {
  color: rgb(224 242 254);
  text-shadow: 0 0 20px rgba(56, 189, 248, 0.5);
}

.pdf-tab-primary-facet:hover:not(:disabled) {
  color: rgb(110 235 183);
  text-shadow: 0 0 20px rgba(52, 211, 153, 0.55);
}

.pdf-tab-primary-facet:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.pdf-tab-primary-facet:focus-visible {
  outline: 2px solid rgba(52, 211, 153, 0.45);
  outline-offset: 2px;
}

.pdf-tab-primary-facet[aria-selected="true"]:not(:disabled) {
  color: rgb(248 250 252);
}

.pdf-tab-primary-track[data-side="answers"] .pdf-tab-primary-facet#tab-btn-answers:not(:disabled) {
  color: rgb(167 243 208);
  text-shadow: 0 0 18px rgba(52, 211, 153, 0.3);
}

/* Layout toggles: icon colors match .dl-icon-btn--sky / --amber / --violet */
.pdf-tab-layout-btn {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 0;
  width: 100%;
  padding: 0.35rem 0.4rem;
  border: none;
  border-radius: 9999px;
  background: transparent;
  cursor: pointer;
  transition: color 0.28s ease, opacity 0.28s ease, transform 0.22s cubic-bezier(0.22, 1, 0.36, 1), filter 0.28s ease;
}

.pdf-tab-layout-btn--sky {
  color: rgb(125 211 252);
  filter: drop-shadow(0 0 10px rgba(56, 189, 248, 0.5));
}

.pdf-tab-layout-btn--amber {
  color: rgb(253 230 138);
  filter: drop-shadow(0 0 10px rgba(251, 191, 36, 0.45));
}

.pdf-tab-layout-btn--violet {
  color: rgb(216 180 254);
  filter: drop-shadow(0 0 10px rgba(167, 139, 250, 0.45));
}

.pdf-tab-layout-btn:hover:not(:disabled) {
  transform: scale(1.14) translateY(-0.5px);
}

.pdf-tab-layout-btn:active:not(:disabled) {
  transform: scale(0.95);
}

.pdf-tab-layout-btn--sky:hover:not(:disabled) {
  color: rgb(224 242 254);
  filter: drop-shadow(0 0 20px rgba(56, 189, 248, 0.8)) drop-shadow(0 0 6px rgba(56, 189, 248, 0.5));
}

.pdf-tab-layout-btn--amber:hover:not(:disabled) {
  color: rgb(254 249 195);
  filter: drop-shadow(0 0 20px rgba(251, 191, 36, 0.75)) drop-shadow(0 0 6px rgba(251, 191, 36, 0.45));
}

.pdf-tab-layout-btn--violet:hover:not(:disabled) {
  color: rgb(237 233 254);
  filter: drop-shadow(0 0 20px rgba(167, 139, 250, 0.75)) drop-shadow(0 0 6px rgba(167, 139, 250, 0.45));
}

.pdf-tab-layout-btn--sky[aria-selected="true"]:not(:disabled) {
  color: rgb(34 211 238);
  filter: drop-shadow(0 0 16px rgba(34, 211, 238, 0.65));
}

.pdf-tab-layout-btn--amber[aria-selected="true"]:not(:disabled) {
  color: rgb(251 191 36);
  filter: drop-shadow(0 0 16px rgba(251, 191, 36, 0.6));
}

.pdf-tab-layout-btn--violet[aria-selected="true"]:not(:disabled) {
  color: rgb(192 132 252);
  filter: drop-shadow(0 0 16px rgba(192, 132, 252, 0.6));
}

.pdf-tab-layout-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
  filter: none;
}

.pdf-tab-layout-btn:focus-visible {
  outline: 2px solid var(--glow-cyan, rgba(34, 211, 238, 0.45));
  outline-offset: 2px;
}

.pdf-tab-layout-btn--amber:focus-visible {
  outline-color: rgba(251, 191, 36, 0.5);
}

.pdf-tab-layout-btn--violet:focus-visible {
  outline-color: rgba(167, 139, 250, 0.5);
}

.pdf-tab-layout-icon {
  display: flex;
  width: 1.35rem;
  height: 1.35rem;
}

.pdf-tab-layout-icon svg {
  width: 100%;
  height: 100%;
}

.gen-left-col {
  width: 100%;
  max-width: 42rem;
  margin-left: auto;
  margin-right: auto;
}

.preview-mode .gen-left-col {
  margin-left: 0;
  margin-right: 0;
}

@media (min-width: 1024px) {
  .preview-mode .gen-left-col {
    width: var(--left-col-width);
    max-width: var(--left-col-width);
    flex-shrink: 0;
    grid-column: 1;
    grid-row: 1;
  }
}

.hero-collapse {
  max-height: 40rem;
  opacity: 1;
  overflow: hidden;
  transition:
    max-height 0.32s cubic-bezier(0.22, 1, 0.36, 1),
    opacity 0.22s ease,
    margin 0.28s ease;
}

/* Landing: allow hover lifts + hero icon float without clipping top borders */
#generate-workspace:not(.preview-mode) .hero-collapse {
  overflow: visible;
}

.preview-mode .hero-collapse {
  max-height: 0;
  opacity: 0;
  margin-top: 0 !important;
  margin-bottom: 0 !important;
  pointer-events: none;
}

.preview-mode #gen-form {
  margin-top: 0;
}

/* Specificity: form#gen-form (1,0,1) beats Tailwind's [type="text"] (0,1,1) — no !important needed. */
.preview-mode form#gen-form #prompt {
  min-height: 8rem;
  max-height: min(42vh, 22rem);
  resize: vertical;
  border-color: rgba(56, 189, 248, 0.22);
  background: linear-gradient(
    165deg,
    rgba(6, 22, 42, 0.92) 0%,
    rgba(4, 16, 36, 0.88) 45%,
    rgba(8, 28, 52, 0.85) 100%
  );
  color: rgb(226 232 240);
  box-shadow:
    inset 0 1px 0 rgba(56, 189, 248, 0.06),
    inset 0 0 0 1px rgba(0, 0, 0, 0.25),
    0 0 28px -10px rgba(56, 189, 248, 0.15);
  caret-color: rgb(34 211 238);
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.preview-mode form#gen-form #prompt::placeholder {
  color: rgba(186, 240, 253, 0.52);
}

.preview-mode form#gen-form #prompt:hover {
  border-color: rgba(56, 189, 248, 0.32);
  box-shadow:
    inset 0 1px 0 rgba(56, 189, 248, 0.1),
    inset 0 0 0 1px rgba(0, 0, 0, 0.2),
    0 0 32px -8px rgba(56, 189, 248, 0.22);
}

.preview-mode form#gen-form #prompt:focus {
  border-color: rgba(34, 211, 238, 0.45);
  outline: none;
  box-shadow:
    inset 0 1px 0 rgba(56, 189, 248, 0.12),
    inset 0 0 0 1px rgba(0, 0, 0, 0.15),
    0 0 0 2px rgba(34, 211, 238, 0.2),
    0 0 40px -8px rgba(34, 211, 238, 0.25);
}

/* Header nav pills (Generate / Library) — subtle glass + hint of cyan */
body.preview-mode-active .site-header-nav {
  border-color: rgba(56, 189, 248, 0.14) !important;
  background: linear-gradient(
    180deg,
    rgba(12, 22, 42, 0.52) 0%,
    rgba(8, 14, 32, 0.58) 100%
  ) !important;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.05),
    0 0 0 1px rgba(56, 189, 248, 0.035) inset,
    0 3px 18px -8px rgba(0, 0, 0, 0.38),
    0 0 28px -14px rgba(56, 189, 248, 0.07);
  backdrop-filter: blur(12px) saturate(1.06);
  -webkit-backdrop-filter: blur(12px) saturate(1.06);
}

body.preview-mode-active .site-header-nav a {
  color: rgb(132 165 196) !important;
  transition: color 0.18s ease, background 0.18s ease, box-shadow 0.18s ease;
}

body.preview-mode-active .site-header-nav a:hover {
  color: rgb(203 230 248) !important;
  background: rgba(56, 189, 248, 0.07) !important;
  box-shadow: 0 0 12px -4px rgba(56, 189, 248, 0.12);
}

body.preview-mode-active .site-header-nav a.nav-link-active {
  color: rgb(226 246 255) !important;
  background: linear-gradient(
    135deg,
    rgba(34, 211, 238, 0.16) 0%,
    rgba(59, 130, 246, 0.12) 100%
  ) !important;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.08),
    0 0 0 1px rgba(34, 211, 238, 0.12) inset,
    0 0 14px -4px rgba(34, 211, 238, 0.14);
}

/* Non-preview nav styles live in 03-core-ui.css so they apply on every page. */

#pdf-preview-pane {
  display: none;
  flex-direction: column;
  min-width: 0;
  min-height: 60vh;
  border-radius: 1rem;
  border: 1px solid rgba(255, 255, 255, 0.08);
  background:
    linear-gradient(148deg, rgba(15, 28, 52, 0.75) 0%, rgba(10, 18, 38, 0.5) 100%),
    rgb(2, 6, 16); /* opaque base so page bg never bleeds through */
  box-shadow:
    0 0 0 1px rgba(255, 255, 255, 0.04) inset,
    0 24px 48px -12px rgba(0, 0, 0, 0.45);
  overflow: hidden;
}

@media (min-width: 1024px) {
  .preview-mode .pdf-preview-stack {
    grid-column: 2;
    grid-row: 1;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    min-height: 0;
    height: calc(100vh - var(--preview-sticky-top) - 1rem);
    max-height: calc(100vh - var(--preview-sticky-top) - 1rem);
    margin-top: calc(-1 * var(--preview-sticky-top) - 0.75rem);
    padding-top: 0;
    height: calc(100vh - 1rem);
    max-height: calc(100vh - 1rem);
  }
}

@media (min-width: 1024px) {
  .preview-mode #pdf-preview-pane {
    border-top-left-radius: 0;
    border-top-right-radius: 0;
    border-top: none;
  }

  .preview-mode .pdf-viewport-scroll {
    padding-top: calc(var(--preview-sticky-top) + 0.75rem);
  }
}

.preview-mode #pdf-preview-pane {
  display: flex;
  flex: 1 1 auto;
  min-width: 0;
  min-height: 0;
  width: 100%;
}

/* Tint the pane border to match the active tab */
.preview-mode:has(#pdf-tab-primary-track[data-side="sheet"]) #pdf-preview-pane {
  border-color: rgba(56, 189, 248, 0.26);
  box-shadow:
    0 0 0 1px rgba(56, 189, 248, 0.08) inset,
    0 24px 48px -12px rgba(0, 0, 0, 0.45),
    0 0 56px -16px rgba(56, 189, 248, 0.14);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.preview-mode:has(#pdf-tab-primary-track[data-side="answers"]) #pdf-preview-pane {
  border-color: rgba(52, 211, 153, 0.26);
  box-shadow:
    0 0 0 1px rgba(52, 211, 153, 0.08) inset,
    0 24px 48px -12px rgba(0, 0, 0, 0.45),
    0 0 56px -16px rgba(52, 211, 153, 0.12);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.preview-mode:has(#tab-btn-ranking[aria-selected="true"]) #pdf-preview-pane {
  border-color: rgba(251, 146, 60, 0.28);
  box-shadow:
    0 0 0 1px rgba(251, 146, 60, 0.09) inset,
    0 24px 48px -12px rgba(0, 0, 0, 0.45),
    0 0 56px -16px rgba(251, 146, 60, 0.14);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

@media (max-width: 1023px) {
  .generate-workspace.preview-mode {
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: auto minmax(14rem, 1fr);
  }

  .preview-mode #gen-left-col {
    grid-column: 1;
    grid-row: 1;
  }

  .preview-mode .pdf-preview-stack {
    grid-column: 1;
    grid-row: 2;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    min-height: 0;
    max-height: min(58vh, calc(100vh - var(--preview-sticky-top) - 1.25rem));
    height: min(58vh, calc(100vh - var(--preview-sticky-top) - 1.25rem));
  }
}

.pdf-tab-panels {
  position: relative;
  flex: 1 1 0;
  min-height: 0;
  background: var(--pane-bg); /* opaque — no flash during tab switch */
}

.pdf-tab-panel {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  min-height: 0;
  background: var(--pane-bg); /* opaque fallback — prevents flash of page bg */
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.12s ease, visibility 0s linear 0.12s;
}

/* JS toggles [hidden] alongside .is-active; UA stylesheet would force display:none. */
.pdf-tab-panel[hidden] {
  display: flex;
}

.pdf-tab-panel.is-active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transition: opacity 0.12s ease, visibility 0s;
}

.pdf-viewport-scroll {
  position: relative;
  flex: 1 1 0;
  min-height: 0;
  width: 100%;
  overflow: auto;
  background: rgba(0, 0, 0, 0.4);
  display: flex;
  flex-direction: column;
  align-items: stretch;
  padding: 0.75rem 0.75rem 1.25rem;
  will-change: scroll-position;
  scrollbar-width: thin;
  scrollbar-color: rgba(56, 189, 248, 0.22) transparent;
}

.pdf-viewport-scroll::-webkit-scrollbar { width: 8px; height: 8px; }
.pdf-viewport-scroll::-webkit-scrollbar-track { background: transparent; }
.pdf-viewport-scroll::-webkit-scrollbar-thumb {
  background: rgba(56, 189, 248, 0.22);
  border-radius: 4px;
  border: 2px solid transparent;
  background-clip: padding-box;
}
.pdf-viewport-scroll::-webkit-scrollbar-thumb:hover {
  background: rgba(56, 189, 248, 0.38);
  background-clip: padding-box;
  border: 2px solid transparent;
}
.pdf-viewport-scroll::-webkit-scrollbar-corner { background: transparent; }

.preview-mode .pdf-viewport-scroll {
  display: block;
  background: linear-gradient(180deg, rgba(8, 30, 52, 0.52) 0%, rgba(2, 8, 20, 0.5) 100%);
}

.pdf-pages-stack {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  width: 100%;
  min-width: 0;
  flex-shrink: 0;
  box-sizing: border-box;
}

/* Stack width is managed by JS (renderPdfContinuous / rerenderPdfZoomBuffered):
   max(contentWidth, maxPageWidth) — full-width at normal zoom for centering,
   wider-than-container at high zoom for horizontal overflow. */

/* Allow zoomed page width to exceed the pane so horizontal trackpad scroll works
   (09-overview.css caps .pdf-page-wrap at 100% which prevents overflow-x). */
.pdf-viewport-scroll .pdf-page-wrap {
  max-width: none;
}

/* ─── Portrait phones: scrollable tab track; hide ranking button ─────── */
@media (max-width: 479px) {
  .ranking-tab-area {
    display: none;
  }
  body.preview-mode-active #pdf-tab-bar-wrap:not([hidden]) > .pdf-tab-primary-clip {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    overscroll-behavior-x: contain;
    justify-self: stretch;
    justify-content: flex-start;
  }
}