.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  z-index: 1000;
  background: transparent;
}

.nav-wrap {
  width: min(1120px, 94vw);
  margin: 0.7rem auto 0;
  height: 3.9rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0 0.8rem 0 1rem;
  background: var(--paper);
  box-shadow: 0 2px 8px rgba(31, 37, 33, 0.05);
}

.brand {
  font-weight: 700;
  letter-spacing: -0.03em;
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  font-size: 0.98rem;
}

.brand-dot {
  width: 0.62rem;
  height: 0.62rem;
  border-radius: 999px;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
}

.nav-toggle {
  display: none;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.62);
  border-radius: 10px;
  padding: 0.45rem 0.65rem;
  font-size: 1rem;
}

.nav-list {
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.48rem 0.78rem;
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.95rem;
  border: 1px solid transparent;
  transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease, transform 0.2s ease;
}

.theme-switch {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.5);
  color: var(--ink);
  padding: 0.28rem 0.55rem;
  font: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
}

.theme-switch:hover {
  transform: translateY(-1px);
}

.theme-switch-label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.76rem;
  color: var(--muted);
}

.theme-switch-track {
  width: 2.05rem;
  height: 1.12rem;
  border-radius: 999px;
  background: rgba(31, 37, 33, 0.2);
  position: relative;
}

.theme-switch-track::after {
  content: '';
  position: absolute;
  inset: 0.13rem auto auto 0.13rem;
  width: 0.86rem;
  height: 0.86rem;
  border-radius: 999px;
  background: #fff;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.24);
  transition: transform 0.2s ease;
}

.theme-switch[data-theme-state='dark'] .theme-switch-track {
  background: linear-gradient(135deg, var(--primary), var(--accent));
}

.theme-switch[data-theme-state='dark'] .theme-switch-track::after {
  transform: translateX(0.93rem);
}

body[data-theme='night'] .theme-switch {
  background: rgba(15, 23, 42, 0.55);
}

body[data-theme='night'] .theme-switch-track::after {
  background: #dbeafe;
}

.nav-link:hover,
.nav-link.active {
  color: var(--ink);
  background: rgba(15, 118, 110, 0.14);
  border-color: rgba(15, 118, 110, 0.28);
  transform: translateY(-1px);
}

@media (max-width: 860px) {
  .nav-toggle {
    display: inline-flex;
  }

  .theme-switch-label {
    display: none;
  }

  .theme-switch {
    padding: 0.24rem 0.34rem;
  }

  .nav-list {
    position: absolute;
    top: calc(100% + 0.5rem);
    right: 3vw;
    width: min(320px, 92vw);
    flex-direction: column;
    align-items: stretch;
    background: rgba(255, 249, 241, 0.94);
    backdrop-filter: blur(8px);
    border: 1px solid var(--line);
    border-radius: 16px;
    box-shadow: var(--shadow-soft);
    padding: 0.6rem;
    opacity: 0;
    pointer-events: none;
    transform: translateY(-4px);
    transition: opacity 0.25s cubic-bezier(.2,.8,.2,1), transform 0.25s cubic-bezier(.2,.8,.2,1);
    z-index: 1002;
  }

  .nav-list.open {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
  }

  /* Burger icon visuals (accessible: button keeps its aria-label) */
  .nav-toggle {
    width: 44px;
    height: 36px;
    padding: 0;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.62);
    border-radius: 10px;
    position: relative;
    font-size: 0; /* hide text visually (aria-label preserved) */
  }

  .nav-toggle span {
    display: block;
    width: 18px;
    height: 2px;
    background: var(--ink);
    border-radius: 2px;
    position: relative;
    transition: transform 0.25s ease, opacity 0.25s ease, background 0.25s ease;
  }

  .nav-toggle span::before,
  .nav-toggle span::after {
    content: '';
    position: absolute;
    left: 0;
    width: 18px;
    height: 2px;
    background: var(--ink);
    border-radius: 2px;
    transition: transform 0.25s ease, opacity 0.25s ease;
  }

  .nav-toggle span::before { top: -6px; }
  .nav-toggle span::after { top: 6px; }

  .nav-toggle[aria-expanded='true'] span { background: transparent; }
  .nav-toggle[aria-expanded='true'] span::before { transform: rotate(45deg) translate(4px,4px); }
  .nav-toggle[aria-expanded='true'] span::after { transform: rotate(-45deg) translate(4px,-4px); }

  /* Page overlay shown when menu is open */
  .nav-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.28);
    z-index: 1000;
    opacity: 1;
    pointer-events: auto;
  }

  .nav-link {
    justify-content: flex-start;
    border-radius: 10px;
    width: 100%;
  }

  body[data-theme='night'] .nav-list {
    background: rgba(15, 23, 42, 0.94);
  }

}