/* =========================================================
   CASE STUDY SECTION RAIL  ·  reusable across all case studies
   Default: a slim dashed tick column flush to the edge, never
   overlapping content. On hover/focus it expands into an opaque
   overlay sheet that slides in from the right with easing.

   Drop-in:
     <link rel="stylesheet" href="case-rail.css">
     ...mark each section:  <section id="overview" data-rail="Overview"> …
     <script src="case-rail.js"></script>   (builds + wires the rail)
   ========================================================= */

:root {
  --csr-ink:    #F4EEE4;
  --csr-dim:    rgba(244,238,228,0.32);
  --csr-mid:    rgba(244,238,228,0.62);
  --csr-coral:  #c49ae0;
  --csr-card:   #1C1C1C;
  --csr-line:   rgba(244,238,228,0.14);
  --csr-ease:   cubic-bezier(0.22, 1, 0.36, 1);
  --csr-serif:  "Bricolage Grotesque", system-ui, sans-serif;
}

[data-rail] { scroll-margin-top: 96px; }

.csrail {
  position: fixed;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  z-index: 95;
  font-family: var(--csr-serif);
  -webkit-font-smoothing: antialiased;
  opacity: 0;
  pointer-events: none;
  transition: opacity .5s var(--csr-ease);
}
.csrail.is-visible {
  opacity: 1;
  pointer-events: auto;
}
.csrail__inner {
  position: relative;
  display: flex;
  align-items: center;
}

/* ---- default collapsed state: dashed ticks flush to the edge, no overlap with content ---- */
.csrail__dashes {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 8px;
  padding: 8px 6px;
  cursor: pointer;
}
.csrail__dash {
  width: 13px;
  height: 2px;
  border-radius: 1px;
  background: var(--csr-dim);
  transition: background .35s var(--csr-ease), width .35s var(--csr-ease);
}
.csrail__dash.is-active { width: 21px; background: var(--csr-coral); }
.csrail__dashes:hover .csrail__dash:not(.is-active) { background: var(--csr-mid); width: 17px; }
.csrail.is-open .csrail__dashes { opacity: 0; transition: opacity .25s var(--csr-ease) .1s; }

/* ---- expanded sheet: opaque overlay, slides in from the edge with easing ---- */
.csrail__sheet {
  position: absolute;
  top: 50%;
  right: 10px;
  transform: translate(16px, -50%);
  min-width: 226px;
  padding: 22px 24px;
  border-radius: 18px;
  background: var(--csr-card);
  border: 1px solid var(--csr-line);
  box-shadow: 0 24px 48px -18px rgba(0,0,0,0.55);
  opacity: 0;
  visibility: hidden;
  transition: transform .55s var(--csr-ease), opacity .4s var(--csr-ease), visibility 0s linear .55s;
}
.csrail.is-open .csrail__sheet {
  transform: translate(0, -50%);
  opacity: 1;
  visibility: visible;
  transition: transform .55s var(--csr-ease), opacity .4s var(--csr-ease), visibility 0s;
}

.csrail__list {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 3px;
  text-align: right;
}

.csrail__item {
  display: block;
  text-align: right;
  white-space: nowrap;
  padding: 6px 4px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--csr-dim);
  cursor: pointer;
  transition: color .3s var(--csr-ease);
}
.csrail__label {
  display: inline-block;
  vertical-align: middle;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: -0.005em;
  line-height: 1.2;
  color: inherit;
}
.csrail__item:hover { color: var(--csr-mid); }
.csrail__item:focus-visible { outline: 2px solid var(--csr-coral); outline-offset: 3px; }
.csrail__item.is-active { color: var(--csr-ink); font-weight: 700; }

@media (prefers-reduced-motion: reduce) {
  .csrail *, .csrail { transition-duration: .01ms !important; }
}

/* hide on narrower viewports so it never overlaps the centered content column */
@media (max-width: 1100px) {
  .csrail { display: none; }
}

.csrail-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 96;
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--csr-card);
  border: 1px solid var(--csr-line);
  color: var(--csr-mid);
  cursor: pointer;
  box-shadow: 0 14px 34px -12px rgba(0,0,0,0.55);
  opacity: 0;
  transform: translateY(10px);
  pointer-events: none;
  transition: opacity .35s var(--csr-ease), transform .35s var(--csr-ease), color .25s var(--csr-ease), border-color .25s var(--csr-ease);
}
.csrail-top.is-visible { opacity: 1; transform: translateY(0); pointer-events: auto; }
.csrail-top:hover { color: var(--csr-ink); border-color: var(--csr-coral); }
.csrail-top svg { width: 19px; height: 19px; }
@media (max-width: 640px) { .csrail-top { right: 16px; bottom: 16px; width: 42px; height: 42px; } }