/* Persistent Navigation Styles - Compact Version */
.walkthrough-nav {
  position: fixed;
  left: var(--nav-left);
  top: 52px; /* near the hamburger */
  transform: none;
  width: var(--nav-width);
  max-height: 80vh;
  overflow-y: auto;
  background: rgba(248, 250, 252, 0.95);
  backdrop-filter: blur(8px);
  border-radius: 8px;
  border: 1px solid var(--border-color);
  box-shadow: 0 4px 16px rgba(0, 38, 118, 0.08);
  z-index: 100;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}
.walkthrough-nav.visible { opacity: 1; visibility: visible; }

.nav-toggle {
  position: fixed;
  top: 12px;
  left: var(--nav-left);
  width: 38px;
  height: 38px;
  background: var(--hover-bg);
  color: var(--burger-line-color);
  border: 1px solid var(--burger-border-color);
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
  z-index: 1000;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.nav-toggle:hover { background: var(--hover-bg); }

.nav-header { padding: 12px 16px 8px 16px; border-bottom: 1px solid var(--border-color); }
.nav-header h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--berkeley-blue);
  margin: 0;
}
.nav-section { border-bottom: 1px solid var(--border-color); padding: 12px 0; }
.nav-section:last-child { border-bottom: none; }
.nav-section-title {
  font-size: 0.7rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 6px;
  padding: 0 16px;
}
.nav-link {
  display: block;
  padding: 5px 12px;
  color: var(--berkeley-blue);
  text-decoration: none;
  font-size: 0.8rem;
  line-height: 1.3;
  transition: all 0.2s ease;
  border-left: 2px solid transparent;
}
.nav-link:hover { background: var(--hover-bg); border-left-color: var(--berkeley-blue-60); }
.nav-link.active { background: var(--berkeley-blue); color: white; font-weight: 500; border-left-color: var(--gold-medium); }

/* ──────────────────────────────────────────────────────────────
   Mobile/tablet: overlay nav; DO NOT move the body when opened
   ────────────────────────────────────────────────────────────── */
@media (max-width: 979px) {
  .walkthrough-nav {
    top: 52px;
    left: var(--nav-left);
    transform: none;
    width: var(--nav-width); /* fixed */
    background: rgba(248, 250, 252, 0.35); /* translucent overlay look */
    max-height: 75vh;
    display: block;
  }

  /* Body should not shift when nav opens on mobile/tablet */
  html.nav-open .container {
    /* Explicitly restate the closed-state margins (no movement) */
    margin-inline-start: auto;
    margin-inline-end: var(--content-right-gap);
    /* Physical fallbacks */
    margin-left: auto;
    margin-right: var(--content-right-gap);
  }
}

/* ──────────────────────────────────────────────────────────────
   Desktop refinements
   ────────────────────────────────────────────────────────────── */
@media (min-width: 980px) {
  .walkthrough-nav {
    width: var(--nav-width);
  }
  .nav-link { font-size: 0.8rem; padding: 5px 12px; }
  .nav-section-title { font-size: 0.7rem; }
}

/* Desktop: nav OPEN → center content in remaining space */
@media (min-width: 980px) {
  html.nav-open .container {
    /* Use 100% (layout width), not 100vw (which includes scrollbar) */
    /* Logical margins (primary) */
    margin-inline-start: calc(var(--left-rail) + (100% - var(--left-rail) - var(--content-max)) / 2);
    margin-inline-end: auto;
    /* Physical fallbacks */
    margin-left: calc(var(--left-rail) + (100% - var(--left-rail) - var(--content-max)) / 2);
    margin-right: auto;
  }
}

/* Desktop: nav CLOSED → center content in full viewport */
@media (min-width: 980px) {
  html:not(.nav-open) .container {
    /* Logical margins (primary) */
    margin-inline-start: calc((100% - var(--content-max)) / 2);
    margin-inline-end: auto;
    /* Physical fallbacks */
    margin-left: calc((100% - var(--content-max)) / 2);
    margin-right: auto;
  }
}

/* Respect user reduced‑motion preference (nav side only) */
@media (prefers-reduced-motion: reduce) {
  .walkthrough-nav { transition: none !important; }
}