.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 120px;
  height: 100vh;
  background-color: var(--color-surface);
  border-right: 1px solid var(--color-border);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

.site-header__inner {
  display: flex;
  flex-direction: column;
  height: 100%;
  padding: var(--space-5) 0;
}

.site-header__brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: 0 var(--space-4);
  margin-bottom: var(--space-6);
  text-decoration: none;
  flex-shrink: 0;
}

.site-header__logo {
  width: 32px;
  height: 32px;
  object-fit: contain;
  flex-shrink: 0;
}

.site-header__brand-text {
  font-size: 16px;
  font-weight: 500;
  color: var(--color-text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.site-header__toggle {
  display: none;
}

.site-header__nav {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-height: 0;
}

.site-header__nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  flex: 1;
}

.site-header__nav-item {
  margin: 0;
  padding: 0;
}

.site-header__nav-link {
  display: block;
  padding: var(--space-3) var(--space-4);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  text-decoration: none;
  border-left: 3px solid transparent;
  transition: color var(--transition-fast), background-color var(--transition-fast), border-color var(--transition-fast);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.site-header__nav-link:hover {
  color: var(--color-text-primary);
  background-color: var(--color-surface-elevated);
  text-decoration: none;
}

.site-header__nav-link[aria-current="page"] {
  color: var(--color-text-primary);
  border-left-color: var(--color-accent);
  background-color: rgba(99, 102, 241, 0.08);
}

.site-header__cta {
  margin: var(--space-5) var(--space-4) 0;
  flex-shrink: 0;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

@media (max-width: 1423px) {
  .site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    width: 100%;
    height: var(--mobile-bar-height);
    border-right: none;
    border-bottom: 1px solid var(--color-border);
    flex-direction: row;
    align-items: center;
  }

  .site-header__inner {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    padding: 0 var(--space-4);
  }

  .site-header__brand {
    margin-bottom: 0;
    padding: 0;
    gap: var(--space-2);
  }

  .site-header__logo {
    width: 28px;
    height: 28px;
  }

  .site-header__brand-text {
    font-size: 15px;
  }

  .site-header__toggle {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    gap: 5px;
    width: 44px;
    height: 44px;
    padding: 0;
    background: transparent;
    border: none;
    cursor: pointer;
    flex-shrink: 0;
  }

  .site-header__toggle-line {
    display: block;
    width: 22px;
    height: 2px;
    background-color: var(--color-text-primary);
    border-radius: 1px;
    transition: transform var(--transition-fast), opacity var(--transition-fast);
  }

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

  .site-header__toggle[aria-expanded="true"] .site-header__toggle-line:nth-child(2) {
    opacity: 0;
  }

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

  .site-header__nav {
    position: fixed;
    top: var(--mobile-bar-height);
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--color-surface);
    border-top: 1px solid var(--color-border);
    padding: var(--space-5) var(--space-4);
    transform: translateY(-100%);
    visibility: hidden;
    transition: transform var(--transition-fast), visibility var(--transition-fast);
    overflow-y: auto;
    z-index: 999;
    display: flex;
    flex-direction: column;
    gap: var(--space-5);
  }

  .site-header__nav.is-open {
    transform: translateY(0);
    visibility: visible;
  }

  .site-header__nav-list {
    flex: none;
    gap: var(--space-2);
  }

  .site-header__nav-link {
    padding: var(--space-3) var(--space-4);
    font-size: 16px;
    letter-spacing: 0.02em;
    text-transform: none;
    border-left: none;
    border-radius: var(--radius-small);
  }

  .site-header__nav-link[aria-current="page"] {
    border-left: none;
    background-color: rgba(99, 102, 241, 0.12);
  }

  .site-header__cta {
    margin: 0;
    width: 100%;
  }
}

@media (min-width: 1024px) {
  body {
    padding-left: var(--rail-width);
  }
}