/* ============================================================
   Understanding Your Robot-Assisted Screw Placement
   Patient education walkthrough — design tokens + base styles
   ============================================================ */

:root {
  /* Fluid type scale */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.35vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.25vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.75vw, 1.5rem);
  --text-xl: clamp(1.5rem, 1.2rem + 1.25vw, 2.25rem);
  --text-2xl: clamp(2rem, 1.2rem + 2.5vw, 3.25rem);

  /* 4px spacing system */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  --radius-sm: 0.375rem;
  --radius-md: 0.625rem;
  --radius-lg: 1rem;
  --radius-xl: 1.5rem;
  --radius-full: 9999px;

  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);

  --content-narrow: 640px;
  --content-default: 920px;
  --content-wide: 1180px;

  --font-display: 'DM Sans', 'DM Sans', 'Helvetica Neue', sans-serif;
  --font-body: 'DM Sans', 'Helvetica Neue', sans-serif;
}

/* -------- Light mode (default) -------- */
:root,
[data-theme='light'] {
  --color-bg: #FAF8F6;
  --color-surface: #ffffff;
  --color-surface-2: #FDFBF9;
  --color-surface-offset: #F5F1ED;
  --color-surface-offset-2: #EDE7E1;
  --color-surface-dynamic: #E4DBD3;
  --color-divider: #EBE4DD;
  --color-border: #DCD2C8;

  --color-text: #1F1A16;
  --color-text-muted: #6B6058;
  --color-text-faint: #9C9189;
  --color-text-inverse: #FFFBF8;

  --color-primary: #1e40af;
  --color-primary-hover: #0a48a9;
  --color-primary-active: #0c51bc;
  --color-primary-highlight: #eff4ff;

  --color-warning: #8a5a1c;
  --color-warning-highlight: #f1e3cd;

  --shadow-sm: 0 1px 2px oklch(0.2 0.02 200 / 0.06);
  --shadow-md: 0 6px 20px oklch(0.2 0.02 200 / 0.08);
  --shadow-lg: 0 16px 40px oklch(0.2 0.02 200 / 0.14);
}

/* -------- Dark mode -------- */
[data-theme='dark'] {
  --color-bg: #15120F;
  --color-surface: #1B1713;
  --color-surface-2: #201B16;
  --color-surface-offset: #241E19;
  --color-surface-offset-2: #2B241E;
  --color-surface-dynamic: #372E26;
  --color-divider: #2F2822;
  --color-border: #42382E;

  --color-text: #EFE8E0;
  --color-text-muted: #A79C92;
  --color-text-faint: #7A6E64;
  --color-text-inverse: #15120F;

  --color-primary: #5c9cf9;
  --color-primary-hover: #8ab4fb;
  --color-primary-active: #0063c9;
  --color-primary-highlight: #1a2b4d;

  --color-warning: #d9a24f;
  --color-warning-highlight: #3a2f1c;

  --shadow-sm: 0 1px 2px oklch(0 0 0 / 0.3);
  --shadow-md: 0 6px 20px oklch(0 0 0 / 0.35);
  --shadow-lg: 0 16px 40px oklch(0 0 0 / 0.45);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg: #15120F;
    --color-surface: #1B1713;
    --color-surface-2: #201B16;
    --color-surface-offset: #241E19;
    --color-surface-offset-2: #2B241E;
    --color-surface-dynamic: #372E26;
    --color-divider: #2F2822;
    --color-border: #42382E;
    --color-text: #EFE8E0;
    --color-text-muted: #A79C92;
    --color-text-faint: #7A6E64;
    --color-text-inverse: #15120F;
    --color-primary: #5c9cf9;
    --color-primary-hover: #8ab4fb;
    --color-primary-active: #0063c9;
    --color-primary-highlight: #1a2b4d;
    --color-warning: #d9a24f;
    --color-warning-highlight: #3a2f1c;
  }
}

/* ============ Base reset ============ */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  -webkit-text-size-adjust: none;
  text-size-adjust: none;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: var(--space-24);
}

body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  transition:
    background-color var(--transition-interactive),
    color var(--transition-interactive);
}

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

ul[role='list'] {
  list-style: none;
}

button {
  font: inherit;
  color: inherit;
  cursor: pointer;
  background: none;
  border: none;
}

h1,
h2,
h3 {
  font-family: var(--font-display);
  text-wrap: balance;
  line-height: 1.15;
  font-weight: 600;
}

p,
li {
  text-wrap: pretty;
}

::selection {
  background: color-mix(in oklab, var(--color-primary) 25%, transparent);
  color: var(--color-text);
}

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

a,
button,
[role='button'] {
  transition:
    color var(--transition-interactive),
    background var(--transition-interactive),
    border-color var(--transition-interactive),
    box-shadow var(--transition-interactive),
    transform var(--transition-interactive);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* ============ Skip link ============ */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  background: var(--color-primary);
  color: var(--color-text-inverse);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-sm);
  z-index: 100;
  font-size: var(--text-sm);
}
.skip-link:focus {
  top: var(--space-2);
}

/* ============ Layout shells ============ */
.wrap {
  width: 100%;
  max-width: var(--content-wide);
  margin-inline: auto;
  padding-inline: var(--space-5);
}
.wrap--narrow {
  max-width: var(--content-narrow);
}

/* ============ Header ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in oklab, var(--color-bg) 88%, transparent);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-divider);
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding-block: var(--space-4);
}
.brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
}
.brand__mark {
  width: 34px;
  height: 34px;
  color: var(--color-primary);
  flex-shrink: 0;
}
.brand__text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
  min-width: 0;
}
.brand__title {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.brand__subtitle {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  flex-shrink: 0;
}
.theme-toggle:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background: var(--color-primary-highlight);
}
.theme-toggle svg {
  width: 18px;
  height: 18px;
}

/* ============ Hero / intro ============ */
.hero {
  padding-block: clamp(var(--space-12), 6vw, var(--space-20)) clamp(var(--space-10), 5vw, var(--space-16));
}
.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-primary);
  background: var(--color-primary-highlight);
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-5);
}
.hero__title {
  font-size: var(--text-2xl);
  max-width: 18ch;
  margin-bottom: var(--space-5);
}
.hero__lede {
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  max-width: 58ch;
  margin-bottom: var(--space-8);
  font-weight: 400;
}
.hero__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-5);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  font-weight: 600;
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-full);
  min-height: 44px;
}
.btn-primary {
  background: var(--color-primary);
  color: var(--color-text-inverse);
}
.btn-primary:hover {
  background: var(--color-primary-hover);
}
.btn-primary:active {
  background: var(--color-primary-active);
}
.btn-ghost-link {
  color: var(--color-text);
  font-size: var(--text-sm);
  font-weight: 500;
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: var(--color-border);
}
.btn-ghost-link:hover {
  color: var(--color-primary);
  text-decoration-color: var(--color-primary);
}

.hero__grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: var(--space-3);
  margin-top: clamp(var(--space-10), 5vw, var(--space-16));
}
.hero__grid-item {
  aspect-ratio: 1;
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-surface-offset);
  border: 1px solid var(--color-divider);
  position: relative;
}
.hero__grid-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.hero__grid-item span {
  position: absolute;
  bottom: var(--space-2);
  left: var(--space-2);
  background: color-mix(in oklab, var(--color-bg) 78%, transparent);
  color: var(--color-text);
  font-size: var(--text-xs);
  font-weight: 600;
  padding: 1px var(--space-2);
  border-radius: var(--radius-sm);
}

/* ============ Walkthrough section ============ */
.walkthrough {
  padding-block: clamp(var(--space-10), 5vw, var(--space-16));
  border-top: 1px solid var(--color-divider);
}

/* Progress rail */
.progress {
  margin-bottom: clamp(var(--space-8), 4vw, var(--space-12));
}
.progress__meta {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: var(--space-4);
  gap: var(--space-4);
}
.progress__count {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text);
}
.progress__phase {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.progress__track {
  display: flex;
  gap: var(--space-1);
}
.progress__seg {
  flex: 1;
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--color-surface-dynamic);
  overflow: hidden;
}
.progress__seg-fill {
  height: 100%;
  width: 0%;
  background: var(--color-primary);
  border-radius: var(--radius-full);
  transition: width 420ms cubic-bezier(0.16, 1, 0.3, 1);
}
.progress__seg.is-complete .progress__seg-fill {
  width: 100%;
}
.progress__seg.is-current .progress__seg-fill {
  width: 100%;
}

/* Viewer */
.viewer {
  display: grid;
  grid-template-columns: 1.1fr 1fr;
  gap: clamp(var(--space-6), 4vw, var(--space-12));
  align-items: center;
}
.viewer__media {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--color-surface-offset);
  border: 1px solid var(--color-divider);
  box-shadow: var(--shadow-md);
  aspect-ratio: 4 / 3;
}
.viewer__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  animation: fade-in 420ms cubic-bezier(0.16, 1, 0.3, 1);
}
.viewer__media-fallback {
  position: absolute;
  inset: 0;
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  color: var(--color-text-faint);
  text-align: center;
  padding: var(--space-6);
}
.viewer__media-fallback svg {
  width: 32px;
  height: 32px;
}
.viewer__step-badge {
  position: absolute;
  top: var(--space-4);
  left: var(--space-4);
  background: color-mix(in oklab, var(--color-surface) 85%, transparent);
  backdrop-filter: blur(8px);
  color: var(--color-text);
  font-size: var(--text-xs);
  font-weight: 700;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-full);
  border: 1px solid var(--color-divider);
}

@keyframes fade-in {
  from {
    opacity: 0;
    transform: scale(1.01);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.viewer__content {
  min-width: 0;
}
.viewer__tag {
  display: inline-block;
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--color-primary);
  background: var(--color-primary-highlight);
  padding: var(--space-1) var(--space-3);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-4);
}
.viewer__title {
  font-size: var(--text-xl);
  margin-bottom: var(--space-4);
}
.viewer__body {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  max-width: 56ch;
  margin-bottom: var(--space-8);
}

.viewer__nav {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.nav-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  font-size: var(--text-sm);
  font-weight: 600;
  min-height: 44px;
  color: var(--color-text);
}
.nav-btn svg {
  width: 16px;
  height: 16px;
}
.nav-btn:hover:not(:disabled) {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-highlight);
}
.nav-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}
.nav-btn--primary {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-text-inverse);
}
.nav-btn--primary:hover:not(:disabled) {
  background: var(--color-primary-hover);
  color: var(--color-text-inverse);
}

/* Completion note */
.completion {
  margin-top: var(--space-8);
  padding: var(--space-5) var(--space-6);
  background: var(--color-primary-highlight);
  border-radius: var(--radius-md);
  border: 1px solid color-mix(in oklab, var(--color-primary) 30%, transparent);
  display: none;
}
.completion.is-visible {
  display: block;
  animation: fade-in 420ms cubic-bezier(0.16, 1, 0.3, 1);
}
.completion__title {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-primary-active);
  margin-bottom: var(--space-1);
}
.completion__body {
  font-size: var(--text-sm);
  color: var(--color-text);
}

/* Thumbnail rail */
.rail {
  margin-top: clamp(var(--space-10), 5vw, var(--space-16));
}
.rail__heading {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
}
.rail__list {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: var(--space-3);
}
.rail__item {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: var(--space-2);
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  padding: var(--space-2);
  text-align: left;
  background: transparent;
}
.rail__item:hover {
  background: var(--color-surface-offset);
}
.rail__item.is-active {
  border-color: var(--color-primary);
  background: var(--color-surface-offset);
}
.rail__thumb {
  aspect-ratio: 4 / 3;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--color-surface-offset);
}
.rail__thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.rail__num {
  font-size: var(--text-xs);
  font-weight: 700;
  color: var(--color-text-faint);
}
.rail__item.is-active .rail__num {
  color: var(--color-primary);
}
.rail__label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

/* ============ Disclaimer / footer ============ */
.disclaimer {
  padding-block: clamp(var(--space-8), 4vw, var(--space-12));
  border-top: 1px solid var(--color-divider);
}
.disclaimer__box {
  display: flex;
  gap: var(--space-4);
  align-items: flex-start;
  background: var(--color-warning-highlight);
  border: 1px solid color-mix(in oklab, var(--color-warning) 35%, transparent);
  border-radius: var(--radius-md);
  padding: var(--space-5) var(--space-6);
}
.disclaimer__box svg {
  width: 20px;
  height: 20px;
  color: var(--color-warning);
  flex-shrink: 0;
  margin-top: 2px;
}
.disclaimer__box p {
  font-size: var(--text-sm);
  color: var(--color-text);
}
.disclaimer__box strong {
  color: var(--color-warning);
}

.site-footer {
  padding-block: var(--space-8);
  border-top: 1px solid var(--color-divider);
}
.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}
.site-footer p {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

/* ============ Toolbar (hint + glossary) ============ */
.walkthrough__toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
  flex-wrap: wrap;
}
.walkthrough__hint {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}
.glossary-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  flex-shrink: 0;
  padding: var(--space-2) var(--space-4);
  min-height: 40px;
  border-radius: var(--radius-full);
  border: 1px solid var(--color-border);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text);
}
.glossary-btn svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}
.glossary-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-primary-highlight);
}

/* ============ Hotspots ============ */
.hotspot-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.hotspot {
  --hotspot-color: #ff8a1f;
  --hotspot-color-strong: #e6720a;
  position: absolute;
  transform: translate(-50%, -50%) scale(1);
  width: 34px;
  height: 34px;
  border-radius: var(--radius-full);
  pointer-events: auto;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--hotspot-color);
  border: 2.5px solid #ffffff;
  color: #ffffff;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.4);
  animation: hotspot-bounce 2.1s ease-in-out infinite;
  z-index: 2;
}
.hotspot::before {
  content: '+';
  position: relative;
  z-index: 2;
  font-size: 18px;
  font-weight: 800;
  line-height: 1;
}
.hotspot::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: var(--radius-full);
  border: 2.5px solid var(--hotspot-color);
  animation: hotspot-ring 2.1s ease-out infinite;
  z-index: 1;
}
.hotspot:hover,
.hotspot:focus-visible,
.hotspot.is-active {
  background: var(--hotspot-color-strong);
  color: var(--color-text-inverse);
  animation-play-state: paused;
  transform: translate(-50%, -50%) scale(1.15);
}
.hotspot:hover::after,
.hotspot:focus-visible::after,
.hotspot.is-active::after {
  animation-play-state: paused;
  opacity: 0;
}
@keyframes hotspot-bounce {
  0%,
  100% {
    transform: translate(-50%, -50%) scale(1);
  }
  50% {
    transform: translate(-50%, -50%) scale(1.22);
  }
}
@keyframes hotspot-ring {
  0% {
    transform: scale(1);
    opacity: 0.85;
  }
  100% {
    transform: scale(2.4);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .hotspot,
  .hotspot::after {
    animation: none;
  }
}
@media (max-width: 560px) {
  .hotspot {
    width: 30px;
    height: 30px;
  }
}

/* ============ Term chips (inline glossary triggers) ============ */
.term-chip {
  display: inline;
  font: inherit;
  color: var(--color-primary);
  font-weight: 600;
  text-decoration: underline;
  text-decoration-style: dotted;
  text-underline-offset: 3px;
  text-decoration-thickness: 1.5px;
  border-radius: 3px;
  padding: 0 1px;
}
.term-chip:hover,
.term-chip:focus-visible,
.term-chip.is-active {
  background: var(--color-primary-highlight);
  text-decoration-style: solid;
}

/* ============ Shared info popover (hotspots + term chips) ============ */
.info-popover {
  position: fixed;
  z-index: 200;
  width: min(300px, calc(100vw - var(--space-8)));
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  padding: var(--space-4) var(--space-5);
  padding-right: var(--space-8);
}
.info-popover[hidden] {
  display: none;
}
.info-popover__arrow {
  position: absolute;
  width: 12px;
  height: 12px;
  background: var(--color-surface);
  border-left: 1px solid var(--color-border);
  border-top: 1px solid var(--color-border);
  transform: rotate(45deg);
}
.info-popover--arrow-top .info-popover__arrow {
  top: -7px;
}
.info-popover--arrow-bottom .info-popover__arrow {
  bottom: -7px;
  border-left: none;
  border-top: none;
  border-right: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}
.info-popover__close {
  position: absolute;
  top: var(--space-2);
  right: var(--space-2);
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  color: var(--color-text-muted);
}
.info-popover__close svg {
  width: 14px;
  height: 14px;
}
.info-popover__close:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}
.info-popover__label {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--space-2);
  text-transform: capitalize;
}
.info-popover__text {
  font-size: var(--text-sm);
  color: var(--color-text);
  line-height: 1.55;
}

/* ============ Glossary modal ============ */
.modal-overlay {
  position: fixed;
  inset: 0;
  z-index: 210;
  background: color-mix(in oklab, black 55%, transparent);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-5);
}
.modal-overlay[hidden] {
  display: none;
}
.modal {
  width: 100%;
  max-width: 520px;
  max-height: min(640px, 85vh);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.modal__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-5) var(--space-6);
  border-bottom: 1px solid var(--color-divider);
  flex-shrink: 0;
}
.modal__header h3 {
  font-size: var(--text-lg);
}
.modal__close {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  color: var(--color-text-muted);
}
.modal__close svg {
  width: 16px;
  height: 16px;
}
.modal__close:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}
.modal__list {
  overflow-y: auto;
  padding: var(--space-3) var(--space-6) var(--space-6);
}
.modal__list > div {
  padding-block: var(--space-4);
  border-bottom: 1px solid var(--color-divider);
}
.modal__list > div:last-child {
  border-bottom: none;
}
.modal__list dt {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--space-1);
  text-transform: capitalize;
}
.modal__list dd {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.55;
}

/* ============ Responsive ============ */
@media (max-width: 860px) {
  .viewer {
    grid-template-columns: 1fr;
  }
  .hero__grid {
    grid-template-columns: repeat(5, 1fr);
  }
  .rail__list {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 560px) {
  .hero__grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .hero__grid-item:nth-child(n + 4) {
    display: none;
  }
  .rail__list {
    grid-template-columns: repeat(2, 1fr);
  }
  .brand__subtitle {
    display: none;
  }
  .viewer__nav {
    flex-wrap: wrap;
  }
  .nav-btn {
    flex: 1;
    justify-content: center;
  }
}