/* CaseStudyReadingOverlay — editorial reading surface */

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

.cs-reading-overlay {
  padding: 0;
  border: none;
  background: transparent;
  max-width: none;
  max-height: none;
  width: 100%;
  height: 100%;
  margin: 0;
  color: var(--color-text-primary);
}

.cs-reading-overlay::backdrop {
  background: rgba(15, 15, 15, 0.48);
  opacity: 0;
  transition: opacity 240ms var(--ease-out);
}

.cs-reading-overlay[open]::backdrop,
.cs-reading-overlay.is-open::backdrop {
  opacity: 1;
}

.cs-reading-overlay.is-closing::backdrop {
  opacity: 0;
  transition: opacity 180ms var(--ease-out);
}

.cs-reading-overlay__surface {
  position: fixed;
  inset: 0;
  margin: auto;
  display: flex;
  flex-direction: column;
  width: 100vw;
  height: 100dvh;
  max-height: 100dvh;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  padding-top: env(safe-area-inset-top);
  padding-bottom: env(safe-area-inset-bottom);
  opacity: 0;
  transform: translateY(16px);
  transition:
    opacity 240ms var(--ease-out),
    transform 240ms var(--ease-out);
}

.cs-reading-overlay.is-open .cs-reading-overlay__surface {
  opacity: 1;
  transform: translateY(0) scale(1);
}

.cs-reading-overlay.is-closing .cs-reading-overlay__surface {
  opacity: 0;
  transform: translateY(8px);
  transition:
    opacity 180ms var(--ease-out),
    transform 180ms var(--ease-out);
}

.cs-reading-overlay__header {
  position: sticky;
  top: 0;
  z-index: 2;
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: var(--space-3);
  min-height: 56px;
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}

.cs-reading-overlay__close,
.cs-reading-overlay__back {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  min-width: 44px;
  min-height: 44px;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  background: var(--color-surface);
  color: var(--color-text-primary);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  line-height: 1.2;
  cursor: pointer;
  transition:
    border-color var(--duration-fast) var(--ease-out),
    background-color var(--duration-fast) var(--ease-out);
}

.cs-reading-overlay__close:focus,
.cs-reading-overlay__back:focus {
  outline: none;
}

.cs-reading-overlay__close:focus-visible,
.cs-reading-overlay__back:focus-visible {
  outline: 2px solid var(--color-text-primary);
  outline-offset: 2px;
}

.cs-reading-overlay__close--icon {
  padding: 0;
  width: 44px;
  height: 44px;
}

.cs-reading-overlay__back-label {
  display: inline;
  max-width: 12rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

@media (max-width: 479px) {
  .cs-reading-overlay__back-label {
    max-width: 7.5rem;
  }
}

.cs-reading-overlay__identity {
  min-width: 0;
}

.cs-reading-overlay__kind {
  margin: 0;
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.cs-reading-overlay__title {
  margin: 0.15rem 0 0;
  font-family: var(--font-serif);
  font-size: var(--text-md);
  line-height: var(--leading-snug);
  color: var(--color-text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.cs-reading-overlay__scroll {
  flex: 1;
  min-height: 0;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
}

.cs-reading-overlay__content {
  width: min(68ch, 100%);
  margin: 0 auto;
  padding: var(--space-8) var(--space-5) var(--space-4);
}

.cs-reading-overlay__content .cs-meta {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  margin-top: var(--space-3);
  line-height: var(--leading-loose);
}

.cs-reading-overlay__content .cs-block-label {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-top: var(--space-8);
  margin-bottom: var(--space-2);
}

.cs-reading-overlay__content .cs-route {
  font-family: var(--font-serif);
  font-size: var(--text-3xl);
  line-height: var(--leading-relaxed);
  margin: var(--space-4) 0;
}

.cs-reading-overlay__content .cs-list {
  list-style: none;
  margin-top: var(--space-4);
  padding: 0;
}

.cs-reading-overlay__content .cs-list li {
  padding: var(--space-2) 0;
  padding-left: var(--space-5);
  position: relative;
  font-size: var(--text-lg);
  line-height: var(--leading-loose);
  color: var(--color-text-secondary);
}

.cs-reading-overlay__content .cs-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 14px;
  width: 5px;
  height: 5px;
  border-radius: var(--radius-full);
  background: var(--elz-black);
}

.cs-reading-overlay__footer {
  width: min(68ch, 100%);
  margin: 0 auto;
  padding: var(--space-4) var(--space-5) var(--space-10);
  border-top: 1px solid var(--color-border);
}

body.cs-overlay-open {
  overflow: hidden;
}

@media (min-width: 768px) {
  .cs-reading-overlay__surface {
    width: calc(100vw - 32px);
    height: calc(100dvh - 32px);
    max-height: calc(100dvh - 32px);
    border-radius: var(--radius-xl);
    transform: translateY(12px) scale(0.99);
  }

  .cs-reading-overlay.is-open .cs-reading-overlay__surface {
    transform: translateY(0) scale(1);
  }

  .cs-reading-overlay__header {
    padding: var(--space-4) var(--space-6);
  }

  .cs-reading-overlay__content,
  .cs-reading-overlay__footer {
    padding-left: var(--space-8);
    padding-right: var(--space-8);
  }
}

@media (min-width: 1024px) {
  .cs-reading-overlay__surface {
    width: min(920px, calc(100vw - 64px));
    height: auto;
    max-height: calc(100dvh - 48px);
  }

  .cs-reading-overlay__title {
    font-size: var(--text-lg);
  }
}

@media (hover: hover) and (pointer: fine) {
  .cs-reading-overlay__close:hover,
  .cs-reading-overlay__back:hover {
    border-color: var(--color-text-tertiary);
  }
}

@media (prefers-reduced-motion: reduce) {
  .cs-reading-overlay::backdrop,
  .cs-reading-overlay.is-closing::backdrop,
  .cs-reading-overlay__surface,
  .cs-reading-overlay.is-closing .cs-reading-overlay__surface {
    transition: opacity 120ms linear;
    transform: none;
  }

  .cs-reading-overlay.is-open .cs-reading-overlay__surface {
    transform: none;
  }
}