/* ============================================================================
   Trionic Courses — components.css
   Governs: PLAN.md §7 (Components) + §11 (Required class names)
   Contents: site nav, buttons, course cards, badges, progress UI, lesson
             chrome, quiz, recap, up-next. All tokens come from base.css.
   ============================================================================ */

/* ----------------------------------------------------------------------------
   1. Top navigation
   ---------------------------------------------------------------------------- */

.site-nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  height: 56px;
  padding-inline: var(--space-5);
  background-color: color-mix(in srgb, var(--paper) 80%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-block-end: 1px solid var(--border);
  transition: background-color var(--dur-2) var(--ease-soft);
}

.site-nav > .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  width: 100%;
  height: 100%;
}

.site-nav > .nav-title {
  flex: 1;
  text-align: center;
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--ink-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Brand wordmark */
.brand-mark {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  font-weight: 800;
  letter-spacing: -0.02em;
  font-size: 1.125rem;
  color: var(--ink);
  text-decoration: none;
  line-height: 1;
}

.brand-mark:hover {
  color: var(--ink);
}

/* The accent dot / accent letter — first character gets the brand color */
.brand-mark::first-letter {
  color: var(--brand);
}

/* Optional trailing accent dot — `<span aria-hidden="true">.</span>` */
.brand-mark > span[aria-hidden="true"] {
  color: var(--brand);
  display: inline-block;
  transform-origin: center;
}

@media (prefers-reduced-motion: no-preference) {
  .brand-mark > span[aria-hidden="true"] {
    animation: trionic-pulse-brand 2.4s var(--ease-in-out) infinite;
  }
}

/* Right-hand controls */
.nav-controls {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* Theme + language toggles share an icon-button look */
.theme-toggle,
.lang-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 40px;
  min-height: 40px;
  padding: 0 var(--space-3);
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: 0.875rem;
  color: var(--ink);
  background-color: transparent;
  transition: background-color var(--dur-2) var(--ease-soft),
              color var(--dur-2) var(--ease-soft);
}

.theme-toggle:hover,
.lang-toggle:hover {
  background-color: var(--paper-soft);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

/* Sun / moon visibility flips with the theme. The transition lives outside
   the prefers-reduced-motion guard because base.css's universal override
   forces transitions to 0 globally, and we want a smooth opacity/rotate
   swap when motion IS allowed. */
.theme-toggle .icon-sun,
.theme-toggle .icon-moon {
  transform-origin: center;
  transition: transform var(--dur-2) var(--ease-back),
              opacity var(--dur-2) var(--ease-soft);
}

/* Light theme: moon is visible, sun is hidden + rotated out */
.theme-toggle .icon-sun {
  display: none;
  opacity: 0;
  transform: rotate(-90deg);
  pointer-events: none;
}
.theme-toggle .icon-moon {
  display: block;
  opacity: 1;
  transform: rotate(0deg);
}

/* Dark theme: sun visible, moon hidden + rotated out */
[data-theme="dark"] .theme-toggle .icon-sun {
  display: block;
  opacity: 1;
  transform: rotate(0deg);
  pointer-events: auto;
}
[data-theme="dark"] .theme-toggle .icon-moon {
  display: none;
  opacity: 0;
  transform: rotate(-90deg);
  pointer-events: none;
}

/* Streak pill */
.streak-pill {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  min-height: 36px;
  padding: 0 var(--space-3);
  background-color: var(--brand-soft);
  color: var(--brand-strong);
  border-radius: var(--radius-pill);
  font-weight: 700;
  font-size: 0.875rem;
  font-variant-numeric: tabular-nums;
  line-height: 1;
}

.streak-pill svg {
  width: 14px;
  height: 14px;
}

/* Flame icon hook — Agent 4 may wrap the leading SVG/digit in this class */
.streak-pill__flame {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  transform-origin: center bottom;
}

@media (prefers-reduced-motion: no-preference) {
  .streak-pill:not([hidden]) .streak-pill__flame {
    animation: trionic-flicker 3s var(--ease-soft) infinite;
  }
}

/* ----------------------------------------------------------------------------
   2. Layout primitives
   ---------------------------------------------------------------------------- */

.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: 20px;
}

@media (min-width: 768px) {
  .container {
    padding-inline: 32px;
  }
}

.section {
  padding-block: 48px;
}

.section-tight {
  padding-block: 24px;
}

@media (min-width: 768px) {
  .section {
    padding-block: 64px;
  }
  .section-tight {
    padding-block: 32px;
  }
}

/* ----------------------------------------------------------------------------
   3. Buttons
   ---------------------------------------------------------------------------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 48px;
  padding: 12px 24px;
  border-radius: var(--radius-pill);
  font-weight: 600;
  font-size: 1rem;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--dur-2) var(--ease-soft),
              color var(--dur-2) var(--ease-soft),
              border-color var(--dur-2) var(--ease-soft),
              transform var(--dur-1) var(--ease-out),
              box-shadow var(--dur-2) var(--ease-soft);
  white-space: nowrap;
}

.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.5;
  cursor: not-allowed;
}

/* Primary — solid brand. White text passes AA on #0891b2. */
.btn--primary {
  background-color: var(--brand);
  color: #ffffff;
  border: 2px solid var(--brand);
}

.btn--primary:hover {
  background-color: var(--brand-strong);
  border-color: var(--brand-strong);
  color: #ffffff;
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.btn--primary:active {
  transform: scale(0.97);
  box-shadow: none;
}

/* Dark theme: --brand becomes a bright cyan (#22d3ee). White text on bright
   cyan fails AA, so flip to dark navy text — matches the course-card CTA. */
[data-theme="dark"] .btn--primary {
  color: #0f172a;
}
[data-theme="dark"] .btn--primary:hover {
  color: #0f172a;
}

/* Secondary — outlined brand */
.btn--secondary {
  background-color: transparent;
  color: var(--brand);
  border: 2px solid var(--brand);
}

.btn--secondary:hover {
  background-color: var(--brand-soft);
  color: var(--brand-strong);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.btn--secondary:active {
  transform: scale(0.98);
  box-shadow: none;
}

/* Ghost — text-only */
.btn--ghost {
  background-color: transparent;
  color: var(--brand);
  border: 2px solid transparent;
}

.btn--ghost:hover {
  background-color: var(--paper-soft);
  color: var(--brand-strong);
}

.btn--ghost:active {
  transform: scale(0.98);
}

/* Large variant */
.btn--lg {
  min-height: 56px;
  padding: 16px 32px;
  font-size: 1.125rem;
}

/* ----------------------------------------------------------------------------
   4. Course card
   ---------------------------------------------------------------------------- */

/* Course card — editorial layout: hero cover, overlay pills, icon stats,
   conditional progress, full-width CTA. */
.course-card {
  --card-hue: 195;
  --cover-from: hsl(var(--card-hue) 72% 56%);
  --cover-to:   hsl(var(--card-hue) 82% 42%);
  display: flex;
  flex-direction: column;
  background-color: var(--paper);
  border: 1px solid var(--border);
  border-radius: 18px;
  overflow: hidden;
  text-decoration: none;
  color: inherit;
  position: relative;
  transition: transform var(--dur-2) var(--ease-soft),
              box-shadow var(--dur-3) var(--ease-soft),
              border-color var(--dur-2) var(--ease-soft);
}

.course-card:hover {
  transform: translateY(-4px);
  border-color: color-mix(in srgb, hsl(var(--card-hue) 75% 50%) 40%, var(--border));
  box-shadow: 0 18px 40px -22px rgba(15, 23, 42, 0.18),
              0 4px 10px -4px rgba(15, 23, 42, 0.06);
}

[data-theme="dark"] .course-card:hover {
  box-shadow: 0 18px 40px -16px rgba(0, 0, 0, 0.6),
              0 4px 10px -4px rgba(0, 0, 0, 0.4);
}

/* ---- Cover band (the hero) ---- */
.course-card__cover {
  position: relative;
  height: 200px;
  background: linear-gradient(135deg, var(--cover-from) 0%, var(--cover-to) 100%);
  overflow: hidden;
  isolation: isolate;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Soft radial highlights painted onto the cover for depth */
.course-card__cover-pattern {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 82% 18%, rgba(255, 255, 255, 0.18), transparent 38%),
    radial-gradient(circle at 18% 88%, rgba(0, 0, 0, 0.10), transparent 42%);
  pointer-events: none;
  z-index: 0;
}

/* Diagonal hover shimmer */
.course-card__cover::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(120deg, transparent 38%, rgba(255, 255, 255, 0.22) 50%, transparent 62%);
  background-size: 220% 100%;
  background-position: -100% 0;
  pointer-events: none;
  opacity: 0;
  z-index: 3;
}

/* The illustration — fills the band */
.course-card__art {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 280px;
  padding: 18px 24px;
  color: rgba(255, 255, 255, 0.94);
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}

.course-card__art > svg {
  width: 100%;
  height: auto;
  max-height: 150px;
  display: block;
}

/* Overlay pills — persona top-left, status top-right */
.course-card__persona,
.course-card__status {
  position: absolute;
  top: 14px;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 11px;
  border-radius: var(--radius-pill);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  line-height: 1.2;
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  white-space: nowrap;
}

/* Overlay pills sit on white backgrounds regardless of theme, so their text
   color must NOT bind to var(--ink) (which flips light in dark mode and
   disappears against the white pill). Use a fixed dark ink that reads
   correctly in both themes. */
.course-card__persona {
  left: 14px;
  background-color: rgba(255, 255, 255, 0.94);
  color: #0f172a;
}

.course-card__status {
  right: 14px;
}

.course-card__status--available {
  background-color: rgba(255, 255, 255, 0.94);
  color: hsl(var(--card-hue) 70% 28%);
}

.course-card__status--coming {
  background-color: rgba(15, 23, 42, 0.45);
  color: rgba(255, 255, 255, 0.95);
}

.course-card__status-dot {
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background-color: var(--success);
  display: inline-block;
  flex-shrink: 0;
}

@media (prefers-reduced-motion: no-preference) {
  .course-card.is-mounting {
    animation: trionic-fade-up var(--dur-4) var(--ease-out) both;
    animation-delay: calc(var(--i, 0) * 80ms);
  }

  .course-card:hover .course-card__cover::before {
    opacity: 1;
    animation: trionic-shimmer 1.4s var(--ease-soft);
  }

  .course-card__status--available .course-card__status-dot {
    animation: trionic-pulse-brand 2.2s var(--ease-in-out) infinite;
  }

  /* Subtle scale on the cover SVG when the card is hovered */
  .course-card__art > svg {
    transition: transform var(--dur-4) var(--ease-out);
  }
  .course-card:hover .course-card__art > svg {
    transform: scale(1.04);
  }
}

/* Coming-soon card: slightly muted */
.course-card[data-status="coming-soon"] .course-card__cover {
  filter: saturate(0.85);
}

/* ---- Body ---- */
.course-card__body {
  display: flex;
  flex-direction: column;
  gap: 14px;
  padding: 24px;
  flex: 1;
}

.course-card__title {
  font-size: 1.375rem;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.012em;
  color: var(--ink);
  margin: 0;
}

.course-card__tagline {
  color: var(--ink-muted);
  font-size: 0.9375rem;
  line-height: 1.55;
  margin: 0;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  min-height: calc(0.9375rem * 1.55 * 2); /* keep heights aligned across cards */
}

.course-card__stats {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  flex-wrap: wrap;
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.8125rem;
  color: var(--ink-muted);
  font-weight: 600;
}

.course-card__stats li {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.course-card__stat-icon {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  color: color-mix(in srgb, var(--brand) 80%, var(--ink-muted));
}

/* Progress row — only rendered when the user has started */
.course-card__progress {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--ink-muted);
  margin-block-start: 2px;
}

.course-card__progress .progress-bar {
  flex: 1;
  height: 6px;
  background-color: var(--border);
  border-radius: var(--radius-pill);
  overflow: hidden;
}

.course-card__progress .progress-bar__fill {
  height: 100%;
  background-color: var(--brand);
  border-radius: var(--radius-pill);
}

.course-card__progress-label {
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

/* CTA — full-width, anchored at the bottom of the card.
   Colors are fixed-pair (not theme-bound to --ink/--paper) so the
   button always meets AA contrast regardless of light/dark mode. */
.course-card__cta {
  width: 100%;
  margin-block-start: auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 20px;
  min-height: 52px;
  font-size: 0.9375rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  border-radius: 12px;
  background-color: #0f172a;   /* deep navy, fixed */
  color: #ffffff;              /* white, fixed — AA+ */
  border: none;
  text-decoration: none;
  transition: background-color var(--dur-2) var(--ease-soft),
              transform var(--dur-1) var(--ease-out);
}

.course-card__cta:hover {
  background-color: #1e293b;
  color: #ffffff;
}

[data-theme="dark"] .course-card__cta {
  /* On dark theme, swap to the brand cyan with deep-navy text. Dark text on
     bright cyan reads cleanly; that's the same combo Stripe / Linear use. */
  background-color: var(--brand);
  color: #0f172a;
}
[data-theme="dark"] .course-card__cta:hover {
  background-color: var(--brand-strong);
  color: #0f172a;
}

.course-card__cta-arrow {
  display: inline-flex;
  font-weight: 700;
  transition: transform var(--dur-2) var(--ease-out);
}

@media (prefers-reduced-motion: no-preference) {
  .course-card:hover .course-card__cta-arrow {
    transform: translateX(4px);
  }
}

/* Coming-soon: keep the CTA visible but slightly muted */
.course-card[data-status="coming-soon"] .course-card__cta {
  opacity: 0.78;
}

/* Reduced-motion override for .course-card:hover is handled globally by
   base.css's universal selector — no local override needed. The transform
   on :hover is technically a transition target, which base.css forces to
   ~0ms, so the lift is suppressed. */

/* ----------------------------------------------------------------------------
   5. Persona badge
   ---------------------------------------------------------------------------- */

.persona-badge {
  display: inline-block;
  padding: 4px 12px;
  background-color: var(--brand-soft);
  color: var(--brand-strong);
  border-radius: var(--radius-pill);
  font-size: 0.8125rem;
  font-weight: 600;
  line-height: 1.4;
  white-space: nowrap;
  transform-origin: center;
  transition: transform var(--dur-2) var(--ease-out);
}

.course-card:hover .persona-badge {
  transform: scale(1.02);
}

/* ----------------------------------------------------------------------------
   6. Progress — ring + bar
   ---------------------------------------------------------------------------- */

.progress-ring {
  display: inline-block;
  width: 56px;
  height: 56px;
  flex-shrink: 0;
}

.progress-ring svg {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.progress-ring__track {
  fill: none;
  stroke: var(--border);
  stroke-width: 6;
}

.progress-ring__fill {
  fill: none;
  stroke: var(--brand);
  stroke-width: 6;
  stroke-linecap: round;
  transition: stroke-dashoffset var(--dur-5) var(--ease-out);
}

.progress-ring__label {
  fill: var(--ink);
  font-size: 0.75rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  text-anchor: middle;
  dominant-baseline: middle;
  transform: rotate(90deg);
  transform-origin: center;
}

.progress-bar {
  width: 100%;
  height: 6px;
  background-color: var(--border);
  border-radius: var(--radius-pill);
  overflow: hidden;
}

.progress-bar__fill {
  display: block;
  height: 100%;
  width: 0%;
  background-color: var(--brand);
  border-radius: var(--radius-pill);
  transition: width var(--dur-4) var(--ease-out);
}

/* Indeterminate state — looping shimmer band while data is loading */
@media (prefers-reduced-motion: no-preference) {
  .progress-bar[data-loading="true"] .progress-bar__fill {
    width: 35%;
    background: linear-gradient(
      90deg,
      var(--brand-soft),
      var(--brand),
      var(--brand-soft)
    );
    background-size: 200% 100%;
    animation: trionic-shimmer 1.6s var(--ease-soft) infinite;
  }
}

/* ----------------------------------------------------------------------------
   7. Lesson chrome
   ---------------------------------------------------------------------------- */

.lesson {
  background-color: var(--paper-sunken);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Slim top bar, sticky like .site-nav but 48px */
.lesson-bar {
  position: sticky;
  top: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  gap: var(--space-3);
  height: 48px;
  padding-inline: var(--space-5);
  background-color: color-mix(in srgb, var(--paper) 85%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-block-end: 1px solid var(--border);
}

.lesson-bar .back {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-weight: 600;
  font-size: 0.875rem;
  text-decoration: none;
  color: var(--ink-muted);
  white-space: nowrap;
}

.lesson-bar .back:hover {
  color: var(--brand);
}

/* Visible 4px slide progress bar, flex-grow inside the lesson bar */
.slide-progress {
  flex: 1;
  height: 4px;
  background-color: var(--border);
  border-radius: var(--radius-pill);
  overflow: hidden;
}

.slide-progress > span,
.slide-progress > .slide-progress__fill {
  display: block;
  height: 100%;
  width: 0%;
  background-color: var(--brand);
  border-radius: var(--radius-pill);
  transition: width var(--dur-3) var(--ease-out);
}

/* Slides — only the active one shows */
.slide {
  display: none;
  flex-direction: column;
  gap: var(--space-5);
  width: 100%;
  max-width: var(--reading-column);
  margin-inline: auto;
  padding: 32px 20px;
  min-height: calc(100vh - 56px - 80px);
  justify-content: center;
}

.slide.is-active {
  display: flex;
}

@media (min-width: 768px) {
  .slide {
    padding: 48px 24px;
  }
}

.slide h2 {
  font-size: 1.75rem;
  line-height: 1.25;
}

.slide p {
  font-size: 1.0625rem;
  line-height: 1.7;
}

.slide p + p {
  margin-block-start: var(--space-3);
}

.slide ul,
.slide ol {
  padding-inline-start: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.slide img,
.slide figure {
  border-radius: var(--radius-md);
}

/* ----------------------------------------------------------------------------
   8. Recap card — "What you learned today"
   ---------------------------------------------------------------------------- */

.recap-card {
  background-color: var(--brand-soft);
  border-inline-start: 4px solid var(--brand);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  color: var(--ink);
}

.recap-card h3 {
  font-size: 1.0625rem;
  margin-block-end: var(--space-2);
  color: var(--brand-strong);
}

.recap-card p,
.recap-card li {
  color: var(--ink);
}

@media (prefers-reduced-motion: no-preference) {
  .slide.is-active .recap-card {
    animation: trionic-fade-up var(--dur-4) var(--ease-out) both;
    animation-delay: 120ms;
  }
}

/* ----------------------------------------------------------------------------
   9. Quiz
   ---------------------------------------------------------------------------- */

.quiz {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.quiz__option {
  display: block;
  width: 100%;
  text-align: start;
  padding: 16px;
  background-color: var(--paper);
  color: var(--ink);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  font-weight: 500;
  font-size: 1rem;
  line-height: 1.4;
  cursor: pointer;
  transition: background-color var(--dur-2) var(--ease-soft),
              border-color var(--dur-2) var(--ease-soft),
              color var(--dur-2) var(--ease-soft),
              transform var(--dur-1) var(--ease-out);
}

.quiz__option:hover {
  border-color: var(--brand);
}

.quiz__option:active {
  transform: scale(0.98);
}

.quiz__option.is-correct {
  border-color: var(--success);
  background-color: color-mix(in srgb, var(--success) 12%, var(--paper));
  color: var(--ink);
}

.quiz__option.is-wrong {
  border-color: var(--danger);
  background-color: color-mix(in srgb, var(--danger) 12%, var(--paper));
  color: var(--ink);
}

/* Local keyframe scoped to components.css for wrong-answer shake.
   Uses the `trionic-` prefix to stay in the project namespace; defined
   here (not in base.css) because it's quiz-specific. */
@keyframes trionic-shake-x {
  0%, 100% { transform: translateX(0); }
  25%      { transform: translateX(-4px); }
  75%      { transform: translateX(4px); }
}

@media (prefers-reduced-motion: no-preference) {
  .quiz__option.is-correct {
    animation: trionic-pulse-brand 700ms var(--ease-out) 1;
  }

  .quiz__option.is-wrong {
    animation: trionic-shake-x 320ms var(--ease-out) 1;
  }
}

.quiz__feedback {
  margin-block-start: var(--space-2);
  font-size: 0.9375rem;
  color: var(--ink-muted);
}

@media (prefers-reduced-motion: no-preference) {
  .quiz__feedback:not([hidden]) {
    animation: trionic-fade-up var(--dur-3) var(--ease-out) both;
  }
}

/* ----------------------------------------------------------------------------
   10. Lesson navigation footer
   ---------------------------------------------------------------------------- */

.lesson-nav {
  position: sticky;
  bottom: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: 16px 24px;
  background-color: var(--paper);
  border-block-start: 1px solid var(--border);
}

.lesson-nav .btn {
  min-height: 44px;
  padding: 10px 18px;
}

/* If an arrow span exists inside a next button, nudge it on hover */
.lesson-nav .btn[data-next] .arrow {
  display: inline-block;
  transition: transform var(--dur-2) var(--ease-out);
}

.lesson-nav .btn[data-next]:hover .arrow {
  transform: translateX(2px);
}

.lesson-nav .btn[data-prev] .arrow {
  display: inline-block;
  transition: transform var(--dur-2) var(--ease-out);
}

.lesson-nav .btn[data-prev]:hover .arrow {
  transform: translateX(-2px);
}

.slide-count {
  font-size: 0.875rem;
  color: var(--ink-muted);
  font-variant-numeric: tabular-nums;
  font-family: 'JetBrains Mono', ui-monospace, monospace;
  white-space: nowrap;
}

/* ----------------------------------------------------------------------------
   11. Up next preview
   ---------------------------------------------------------------------------- */

.up-next {
  background-color: var(--paper-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.up-next__label {
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-muted);
}

.up-next__title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--ink);
  text-decoration: none;
  line-height: 1.3;
}

.up-next__title:hover {
  color: var(--brand);
}

/* Arrow that lives inside the title (text "→" or `.up-next__arrow`).
   Hovering the parent card slides it right. */
.up-next__arrow,
.up-next__title > .arrow {
  display: inline-block;
  transition: transform var(--dur-2) var(--ease-out);
  will-change: transform;
}

.up-next:hover .up-next__arrow,
.up-next:hover .up-next__title > .arrow {
  transform: translateX(4px);
}

@media (prefers-reduced-motion: no-preference) {
  .slide.is-active .up-next {
    animation: trionic-fade-up var(--dur-3) var(--ease-out) both;
    animation-delay: 200ms;
  }
}