.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--color-dark-slate);
  border-bottom: 1px solid var(--border-platinum);
  box-shadow: var(--shadow-deep);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-padding);
  min-height: 72px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  color: var(--color-crisp-white);
  flex-shrink: 0;
}

.brand__logo {
  width: 48px;
  height: 48px;
  object-fit: contain;
  display: block;
}

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-body-large);
  font-weight: var(--weight-h2);
  letter-spacing: 0.02em;
  color: var(--color-crisp-white);
  white-space: nowrap;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 5px;
  width: 44px;
  height: 44px;
  padding: 10px;
  background: transparent;
  border: 1px solid var(--border-platinum);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-smooth);
}

.nav-toggle:hover {
  border-color: var(--color-neon-emerald);
  box-shadow: 0 0 10px rgba(0, 255, 136, 0.2);
}

.nav-toggle:focus-visible {
  outline: 2px solid var(--color-neon-emerald);
  outline-offset: 2px;
}

.nav-toggle__line {
  display: block;
  width: 22px;
  height: 2px;
  background-color: var(--color-crisp-white);
  transition: var(--transition-smooth);
  transform-origin: center;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__line:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

.site-nav {
  display: block;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  list-style: none !important;
  margin: 0;
  padding: 0;
}

.site-nav__item {
  margin: 0;
  padding: 0;
}

.site-nav__link {
  display: inline-block;
  padding: var(--space-sm) 0;
  font-family: var(--font-heading);
  font-size: var(--text-body);
  font-weight: var(--weight-h3);
  color: var(--color-platinum);
  text-decoration: none;
  white-space: nowrap;
  transition: var(--transition-smooth);
  position: relative;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: 100%;
  height: 2px;
  background-color: var(--color-neon-emerald);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s ease;
}

.site-nav__link:hover,
.site-nav__link:focus-visible {
  color: var(--color-crisp-white);
}

.site-nav__link:hover::after,
.site-nav__link:focus-visible::after {
  transform: scaleX(1);
}

.site-nav__link:focus-visible {
  outline: 2px solid var(--color-neon-emerald);
  outline-offset: 2px;
}

@media (max-width: 900px) {
  .site-header__inner {
    flex-wrap: wrap;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    flex-basis: 100%;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  .site-nav.is-open {
    max-height: 400px;
    overflow-y: auto;
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding-block: var(--space-md);
  }

  .site-nav__item {
    width: 100%;
  }

  .site-nav__link {
    display: block;
    padding: var(--space-sm) var(--space-md);
    border-radius: var(--radius-sm);
  }

  .site-nav__link::after {
    display: none;
  }

  .site-nav__link:hover,
  .site-nav__link:focus-visible {
    background-color: rgba(0, 255, 136, 0.1);
  }
}

@media (max-width: 480px) {
  .brand__logo {
    width: 36px;
    height: 36px;
  }

  .brand__name {
    display: none;
  }

  .site-header__inner {
    min-height: 60px;
  }
}