/* ── Navbar ── */
#navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 80px;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 var(--pad-x);
  background: var(--nav-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border);
  transition: height var(--transition-smooth), box-shadow var(--transition-smooth);
}

#navbar.scrolled {
  height: 64px;
  box-shadow: 0 4px 30px rgba(0, 0, 0, 0.2);
  border-bottom: 1px solid var(--border-accent);
}

/* Scroll progress indicator */
#scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 0%;
  background: var(--accent);
  z-index: 1001;
  transition: width 0.1s linear;
  box-shadow: 0 0 15px var(--accent-glow), 0 0 5px var(--accent);
  will-change: width, height;
}

/* Vertical mode — HARD override to prevent width bleed bug */
body.vnav-active #scroll-progress {
  top: 0;
  left: 62px;
  width: 2px !important;   /* critical fix */
  height: 0%;
  transition: height 0.1s linear;
}

.nav-logo {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  transition: all var(--transition-smooth);
}

.nav-logo:hover {
  color: var(--accent);
  text-shadow: 0 0 10px var(--accent-glow);
}

.nav-logo span {
  color: var(--accent);
}

.nav-links {
  display: flex;
  gap: 2.5rem;
  list-style: none;
}

.nav-links a {
  font-family: var(--font-mono); /* Using mono for a more tech feel */
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  transition: all var(--transition-smooth);
  position: relative;
  padding: 0.5rem 0;
  will-change: color, text-shadow;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
  text-shadow: 0 0 8px rgba(255, 255, 255, 0.3);
}

/* Scroll-based active indicator (checkpoint glow) */
.nav-links a::after {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 50%;
  width: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
  transition: width 0.4s var(--ease-out-expo), left 0.4s var(--ease-out-expo);
  box-shadow: 0 0 10px var(--accent-glow), 0 0 4px var(--accent);
  will-change: width, left;
}

.nav-links a.active::after {
  width: 100%;
  left: 0;
}

/* Theme toggle */
#theme-toggle {
  width: 44px;
  height: 22px;
  border-radius: 100px;
  background: var(--bg-card);
  border: 1px solid var(--border-hover);
  position: relative;
  cursor: pointer;
  transition: all var(--transition-smooth);
  flex-shrink: 0;
  will-change: box-shadow, border-color;
}

#theme-toggle:hover {
  border-color: var(--accent);
  box-shadow: 0 0 15px var(--accent-glow);
}

#theme-toggle::after {
  content: "";
  position: absolute;
  top: 2px;
  left: 2px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  transition: transform 0.4s var(--ease-out-expo);
  will-change: transform;
  box-shadow: 0 0 8px var(--accent-glow);
}

body.light #theme-toggle::after {
  transform: translateX(22px);
}

/* Mobile Hamburger */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 6px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 5px;
  z-index: 1002;
}

.nav-hamburger span {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--text-primary);
  transition: all var(--transition-smooth);
  border-radius: 2px;
}

.nav-hamburger.open span:nth-child(1) {
  transform: translateY(7.5px) rotate(45deg);
}

.nav-hamburger.open span:nth-child(2) {
  opacity: 0;
}

.nav-hamburger.open span:nth-child(3) {
  transform: translateY(-7.5px) rotate(-45deg);
}

@media (max-width: 900px) {
  .nav-hamburger { display: flex; }
  
  .nav-links {
    position: fixed;
    top: 0;
    right: -100%;
    width: 100%;
    height: 100vh;
    background: var(--bg-primary);
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1.5rem; /* Reduced gap for mobile */
    transition: right 0.3s var(--ease-out-expo);
    box-shadow: -10px 0 30px rgba(0,0,0,0.3);
    border-left: 1px solid var(--border-accent);
    overflow-y: auto;
    padding: 2rem;
  }
  
  .nav-links.open {
    right: 0;
  }
  
  .nav-links a {
    font-size: 1.5rem; /* Increased size for mobile menu */
    letter-spacing: 0.15em;
  }
}

/* ══════════════════════════════════════════════════════════════════════════
   Vertical Sidebar Navbar  (#vnav)
   Rendered only when USE_VERTICAL_NAV = true in js/navbar.js.
   The horizontal #navbar is hidden via JS (display:none) in that mode.
   These rules have zero effect when USE_VERTICAL_NAV = false because
   #vnav is never inserted into the DOM.
══════════════════════════════════════════════════════════════════════════ */

/* Shift page content right when sidebar is active */
body.vnav-active {
  padding-left: 64px;
}

#vnav {
  position: fixed;
  top: 0;
  left: 0;
  width: 64px;
  height: 100vh;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--nav-bg);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-right: 1px solid var(--border);
  padding: 1.5rem 0;
  gap: 0;
  /* Prevent it from creating a scrollbar on body */
  overflow: visible;
}

/* Logo */
.vnav-logo {
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  transition: color var(--transition-smooth);
  flex-shrink: 0;
  line-height: 1;
  margin-bottom: 2rem;
}

.vnav-logo span { color: var(--accent); }

.vnav-logo:hover { color: var(--accent); }

/* Centre column of nav items */
.vnav-items {
  display: flex;
  border-top: 0.1rem solid var(--accent);
  border-bottom: 0.1rem solid var(--accent);
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  flex: 1;
  justify-content: center;
}

/* Shared: each clickable row */
.vnav-item {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  border-radius: 10px;
  text-decoration: none;
  color: var(--text-muted);
  background: transparent;
  border: 1px solid transparent;
  cursor: pointer;
  transition:
    color       var(--transition-snappy),
    background  var(--transition-snappy),
    border-color var(--transition-snappy),
    transform   var(--transition-snappy);
  will-change: transform, color;
  /* button reset */
  font: inherit;
  padding: 0;
}

.vnav-item:hover {
  color: var(--text-primary);
  background: var(--accent-light);
  border-color: var(--border-accent);
  transform: scale(1.08);
}

.vnav-item.active {
  color: var(--accent);
  background: var(--accent-light);
  border-color: var(--border-accent);
}

/* Active left-edge indicator bar */
.vnav-item.active::before {
  content: "";
  position: absolute;
  left: -12px;   /* sits against the sidebar edge */
  top: 50%;
  transform: translateY(-50%);
  width: 3px;
  height: 60%;
  border-radius: 0 2px 2px 0;
  background: var(--accent);
  box-shadow: 0 0 8px var(--accent-glow);
}

/* Icon */
.vnav-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}

.vnav-icon svg {
  width: 17px;
  height: 17px;
  flex-shrink: 0;
}

/* Tooltip (appears to the right on hover) */
.vnav-tooltip {
  position: absolute;
  left: calc(100% + 12px);
  top: 50%;
  transform: translateY(-50%) translateX(-4px);
  background: var(--bg-card);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  white-space: nowrap;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  border: 1px solid var(--border-hover);
  box-shadow: var(--shadow-md);
  opacity: 0;
  pointer-events: none;
  transition:
    opacity    0.18s var(--ease-out-expo),
    transform  0.18s var(--ease-out-expo);
  z-index: 1100;
}

.vnav-item:hover .vnav-tooltip {
  opacity: 1;
  transform: translateY(-50%) translateX(0);
}

/* Bottom slot: theme toggle */
.vnav-bottom {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
  margin-top: 1.5rem;
}

/* Light mode tint */
body.light #vnav {
  border-right-color: var(--border);
  box-shadow: 2px 0 12px rgba(0,0,0,0.06);
}

/* ── Responsive: hide vertical sidebar on small screens ─────────────────── */
@media (max-width: 768px) {
  body.vnav-active { padding-left: 0; }
  #vnav { display: none; }
}