/* ==========================================================================
   Layout shell: side rail, top strip, main column, right rail.
   Linear-style 240px rail + content. Mobile collapses to single column.
   ========================================================================== */

.app {
  display: grid;
  grid-template-columns: var(--rail-w) minmax(0, 1fr);
  min-height: 100vh;
  background: var(--surface-0);
}

/* Mobile-only nav scrim. On desktop it must NOT participate in the grid. */
.rail-scrim { display: none; }

/* ----- Side rail (primary nav) ----- */

.rail {
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--surface-1);
  border-right: 1px solid var(--border-1);
  padding: 18px 14px;
  gap: 6px;
  overflow-y: auto;
}

.rail-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 8px 16px;
  border-bottom: 1px solid var(--border-1);
  margin-bottom: 12px;
  text-decoration: none;
  color: var(--text-1);
}
.rail-brand-mark {
  width: 24px; height: 24px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  background: linear-gradient(135deg, var(--accent), var(--accent-soft));
  color: var(--surface-0);
  font-weight: 700;
  font-size: 12px;
  font-family: var(--font-mono);
}
.rail-brand-text {
  font-weight: 650;
  letter-spacing: -.01em;
  font-size: var(--fs-300);
}
.rail-brand-text small {
  display: block;
  font-size: 10px;
  color: var(--text-3);
  font-family: var(--font-mono);
  letter-spacing: .04em;
  text-transform: uppercase;
  margin-top: 2px;
}

.rail-section {
  margin-top: 12px;
  padding: 0 8px;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-3);
  font-family: var(--font-mono);
}

.rail-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 6px 10px;
  border-radius: 6px;
  color: var(--text-2);
  text-decoration: none;
  font-size: var(--fs-200);
  font-weight: 500;
  letter-spacing: -.005em;
  transition: background var(--dur-fast), color var(--dur-fast);
}
.rail-link:hover {
  background: var(--surface-2);
  color: var(--text-1);
  text-decoration: none;
}
.rail-link[aria-current="page"] {
  background: var(--surface-2);
  color: var(--text-1);
  position: relative;
}
.rail-link[aria-current="page"]::before {
  content: '';
  position: absolute;
  left: -14px;
  top: 50%;
  transform: translateY(-50%);
  width: 2px;
  height: 16px;
  background: var(--accent);
  border-radius: 2px;
}
.rail-link svg, .rail-link .ico {
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
  color: var(--text-3);
}
.rail-link[aria-current="page"] svg,
.rail-link[aria-current="page"] .ico,
.rail-link:hover svg,
.rail-link:hover .ico {
  color: var(--text-1);
}

.rail-status {
  margin-top: auto;
  padding-top: 14px;
  border-top: 1px solid var(--border-1);
  font-size: var(--fs-100);
  font-family: var(--font-mono);
  color: var(--text-3);
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.rail-status .row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 8px;
}
.rail-status .row strong {
  color: var(--text-1);
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

/* ----- Top strip ----- */

.shell {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.topstrip {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  height: var(--topstrip-h);
  padding: 0 24px;
  background: var(--surface-0);
  border-bottom: 1px solid var(--border-1);
  position: sticky;
  top: 0;
  z-index: 30;
  backdrop-filter: blur(8px);
}
.crumbs {
  font-size: var(--fs-200);
  color: var(--text-3);
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  min-width: 0;
}
.crumbs a {
  color: var(--text-3);
  text-decoration: none;
}
.crumbs a:hover { color: var(--text-1); }
.crumbs .sep { color: var(--text-5); }
.crumbs .last { color: var(--text-1); font-weight: 500; }
.topstrip-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.cmd-trigger {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  background: var(--surface-1);
  border: 1px solid var(--border-2);
  border-radius: 6px;
  color: var(--text-3);
  font-size: var(--fs-200);
  font-family: var(--font-sans);
  cursor: pointer;
  transition: background var(--dur-fast), border-color var(--dur-fast);
}
.cmd-trigger:hover { background: var(--surface-2); border-color: var(--border-3); color: var(--text-2); }
.cmd-trigger .kbd {
  font-family: var(--font-mono);
  font-size: 10px;
  padding: 2px 5px;
  background: var(--surface-2);
  border: 1px solid var(--border-2);
  border-radius: 4px;
  color: var(--text-3);
}

.icon-btn {
  width: 32px; height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 6px;
  color: var(--text-3);
  transition: background var(--dur-fast), color var(--dur-fast), border-color var(--dur-fast);
}
.icon-btn:hover { background: var(--surface-2); color: var(--text-1); border-color: var(--border-2); }
.icon-btn[aria-pressed="true"] { color: var(--accent); border-color: var(--border-2); background: var(--surface-2); }

/* ----- Main content area ----- */

.main {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--right-w);
  gap: 32px;
  padding: 32px 32px 96px;
  min-width: 0;
  flex: 1 0 auto;
}
.main.no-rail {
  grid-template-columns: minmax(0, 1fr);
  max-width: var(--content-max);
  margin: 0 auto;
}
.main.full-bleed {
  grid-template-columns: minmax(0, 1fr);
  padding: 0;
  max-width: none;
}

.content {
  min-width: 0;
  max-width: var(--content-max);
}
.content.wide { max-width: none; }

.context {
  position: sticky;
  top: calc(var(--topstrip-h) + 24px);
  align-self: flex-start;
  display: flex;
  flex-direction: column;
  gap: 18px;
  font-size: var(--fs-200);
  color: var(--text-2);
}

/* ----- Mobile collapse ----- */

.rail-toggle {
  display: none;
}

@media (max-width: 960px) {
  .app {
    grid-template-columns: 1fr;
  }
  .rail {
    position: fixed;
    top: 0; left: 0;
    width: 80vw;
    max-width: 320px;
    z-index: 60;
    transform: translateX(-110%);
    transition: transform var(--dur-mid) var(--ease-out);
    box-shadow: var(--shadow-3);
  }
  .rail[data-open="true"] { transform: translateX(0); }
  .rail-toggle {
    display: inline-flex;
  }
  .topstrip {
    padding: 0 16px;
  }
  .main {
    grid-template-columns: minmax(0, 1fr);
    padding: 20px 16px 80px;
  }
  .context {
    position: static;
  }
  .rail-scrim {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, .5);
    z-index: 55;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--dur-mid) var(--ease-out);
  }
  .rail[data-open="true"] ~ .rail-scrim {
    opacity: 1;
    pointer-events: auto;
  }
}

/* ----- Mobile bottom-tab navigation (DESIGN.md §10) ----- */
.bottom-tabs {
  display: none;
}
@media (max-width: 767px) {
  .bottom-tabs {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 40;
    background: color-mix(in oklch, var(--surface-0) 88%, transparent);
    backdrop-filter: blur(10px);
    border-top: 1px solid var(--border-2);
    padding-bottom: env(safe-area-inset-bottom, 0);
    height: calc(64px + env(safe-area-inset-bottom, 0));
  }
  main#main-region { padding-bottom: 80px; }
}
.bottom-tab {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  padding: 8px 4px;
  text-decoration: none;
  color: var(--text-3);
  background: transparent;
  border: none;
  font: inherit;
  cursor: pointer;
  position: relative;
  min-height: 44px;
  transition: color 120ms ease;
}
.bottom-tab:hover { color: var(--text-1); }
.bottom-tab[aria-current="page"] { color: var(--accent); }
.bottom-tab[aria-current="page"]::before {
  content: '';
  position: absolute;
  top: 0;
  left: 24%;
  right: 24%;
  height: 2px;
  background: var(--accent);
  border-radius: 0 0 2px 2px;
}
.bottom-tab-ico { font-size: 18px; line-height: 1; }
.bottom-tab-label {
  font-size: 10px;
  letter-spacing: 0.02em;
  font-weight: 500;
}