/* ============================================================
   Site Header / Navigation
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15, 23, 42, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-divider);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-3);
  height: 64px;
}

.site-header__logo {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-heading);
  font-weight: var(--fw-bold);
  font-size: var(--fs-body-lg);
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.site-header__logo-img {
  height: 28px;
  width: auto;
  display: block;
}

/* Fallback if image fails */
.site-header__logo-mark {
  width: 32px;
  height: 32px;
  display: none;
  align-items: center;
  justify-content: center;
  background: var(--accent);
  border-radius: var(--radius);
  color: #fff;
  font-weight: var(--fw-bold);
  font-size: var(--fs-small);
}

.site-header__logo-img[src=""] ~ .site-header__logo-mark,
.site-header__logo-img:not([src]) ~ .site-header__logo-mark {
  display: flex;
}

.site-header__nav {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.site-header__nav-link {
  font-family: var(--font-heading);
  font-size: var(--fs-small);
  font-weight: var(--fw-medium);
  color: var(--text-secondary);
  transition: color var(--transition-fast);
  padding: var(--space-1) 0;
  position: relative;
}

.site-header__nav-link:hover,
.site-header__nav-link--active {
  color: var(--text-primary);
}

.site-header__nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width var(--transition-base);
}

.site-header__nav-link:hover::after,
.site-header__nav-link--active::after {
  width: 100%;
}

/* Mobile Nav Toggle */
.site-header__menu-toggle {
  display: none;
  width: 36px;
  height: 36px;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
}

.site-header__menu-toggle svg {
  width: 24px;
  height: 24px;
}

@media (max-width: 768px) {
  .site-header__nav {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    flex-direction: column;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-divider);
    padding: var(--space-3);
    gap: var(--space-2);
  }

  .site-header__nav--open {
    display: flex;
  }

  .site-header__menu-toggle {
    display: flex;
  }
}