/* ============================================================
   RAIL — persistent left-hand identity + navigation.
   Same on every page: home and every case study. Shows who you
   are, where you can go, and which part of the site you're in.
   ============================================================ */

.rail {
  position: sticky;
  top: 0;
  align-self: start;
  height: 100dvh;
  width: var(--rail-width);
  flex-shrink: 0;
  padding: var(--space-7) var(--space-5);
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  border-right: 1px solid var(--line);
}

.rail-name {
  font-family: var(--font-sans);
  font-size: var(--text-sub);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.rail-name a { color: inherit; }
.rail-name a:hover { color: var(--accent); }

.rail-role {
  font-size: var(--text-meta);
  color: var(--ink-muted);
  margin-top: var(--space-1);
}

.rail-nav {
  margin-top: var(--space-8);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.rail-nav a {
  position: relative;
  font-size: var(--text-body);
  color: var(--ink-muted);
  padding-left: var(--space-4);
}
.rail-nav a:hover { color: var(--ink); }

.rail-nav a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 6px;
  height: 1px;
  background: var(--line);
}

/* Current section: a tick mark, not a filled highlight */
.rail-nav a[aria-current="true"] {
  color: var(--ink);
  font-weight: 500;
}
.rail-nav a[aria-current="true"]::before {
  background: var(--accent);
  width: 10px;
}

.rail-foot {
  margin-top: auto;
  padding-top: var(--space-6);
  border-top: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.rail-foot a {
  font-size: var(--text-meta);
  font-family: var(--font-mono);
  color: var(--ink-muted);
}
.rail-foot a:hover { color: var(--accent); }

/* ============================================================
   MOBILE — the rail collapses to a plain top bar. No blur,
   no scrim, no materialize transition: an instant disclosure,
   the simplest honest response to the tap that opened it.
   ============================================================ */
.rail-bar {
  display: none;
  position: sticky;
  top: 0;
  z-index: 40;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-5);
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}

.rail-bar-name {
  font-family: var(--font-sans);
  font-size: var(--text-body);
  font-weight: 600;
  color: var(--ink);
}

.rail-bar-toggle {
  font-family: var(--font-mono);
  font-size: var(--text-meta);
  color: var(--ink-muted);
  background: none;
  border: 1px solid var(--line);
  padding: var(--space-1) var(--space-3);
  cursor: pointer;
}
.rail-bar-toggle:hover { border-color: var(--ink-muted); color: var(--ink); }
.rail-bar-toggle:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

@media (max-width: 768px) {
  .rail { display: none; }
  .rail-bar { display: flex; }

  .rail-panel {
    padding: var(--space-5);
    border-bottom: 1px solid var(--line);
    background: var(--paper);
  }
  .rail-panel[hidden] { display: none; }
  .rail-panel .rail-nav { margin-top: 0; }
  .rail-panel .rail-foot { border-top: 1px solid var(--line); margin-top: var(--space-6); }
}