/* ============================================================================
   Nav — Sidebar navigation
   BEM: .nav, .nav__header, .nav__logo, .nav__links, .nav__link,
        .nav__link--active, .nav__footer, .nav__status, .nav__meta
   Mobile-first: off-screen by default, fixed sidebar at md (768px)
   ============================================================================ */

/* -- Block ---------------------------------------------------------------- */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 280px;
  max-width: 85vw;
  height: 100vh;
  background: var(--color-surface);
  border-right: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  padding: var(--space-lg) 0;
  z-index: var(--z-dropdown);
  transform: translateX(-100%);
  transition: transform var(--transition-normal), width var(--transition-normal);
  box-shadow: 2px 0 10px rgba(0, 0, 0, 0.3);
}

.nav--open {
  transform: translateX(0);
}

.nav--collapsed {
  transform: translateX(-100%);
  width: 0;
  overflow: hidden;
}

/* -- Header --------------------------------------------------------------- */

.nav__header {
  padding: var(--space-md) var(--space-lg) var(--space-lg);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-lg);
}

.nav__title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  font-size: var(--text-xl);
  font-weight: var(--weight-bold);
  color: var(--color-accent);
}

/* -- Status --------------------------------------------------------------- */

.nav__status {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  font-size: var(--text-xs);
  color: var(--color-muted);
}

.nav__status--connected {
  color: var(--color-success);
}

/* -- Meta ----------------------------------------------------------------- */

.nav__meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: var(--space-xs);
  font-size: var(--text-xs);
  font-weight: var(--weight-normal);
  color: var(--color-muted);
}

/* -- Links container ------------------------------------------------------ */

.nav__links {
  flex-shrink: 0;
}

/* -- Link ----------------------------------------------------------------- */

.nav__link {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-lg) var(--space-lg);
  color: var(--color-muted);
  text-decoration: none;
  font-size: var(--text-lg);
  min-height: 48px;
  transition: all var(--transition-fast);
  cursor: pointer;
}

.nav__link:hover {
  background: var(--color-bg);
  color: var(--color-text);
}

.nav__link--active {
  background: var(--color-bg);
  color: var(--color-accent);
  border-left: 3px solid var(--color-accent);
}

.nav__link--kb-selected {
  background: var(--color-accent);
  color: #fff;
  border-left: 2px solid var(--color-accent);
  outline: none;
}

.nav__link--kb-selected::before {
  display: none;
}

/* Keyboard shortcut hints */
.nav__link::after {
  content: attr(data-key);
  position: absolute;
  right: var(--space-md);
  font-size: var(--text-xs);
  color: var(--color-muted);
  font-family: var(--font-mono);
  opacity: 0.6;
}

.nav__link--kb-selected::after {
  color: rgba(255, 255, 255, 0.8);
  opacity: 0.8;
}

.nav__link--active::after {
  color: var(--color-accent);
}

/* -- Footer --------------------------------------------------------------- */

.nav__footer {
  padding: var(--space-lg);
  font-size: var(--text-xs);
  font-weight: var(--weight-normal);
  color: var(--color-muted);
  text-align: center;
  border-top: 1px solid var(--color-border);
  line-height: 1.4;
}

/* -- Backdrop (mobile overlay) -------------------------------------------- */

.nav__backdrop {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  z-index: calc(var(--z-dropdown) - 1);
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.nav__backdrop--visible {
  display: block;
  opacity: 1;
}

/* -- Toggle tab (desktop, visible when nav collapsed) --------------------- */

.nav__toggle-tab {
  display: none;
  position: fixed;
  left: 0;
  top: 50%;
  transform: translateY(-50%) translateX(-100%);
  z-index: var(--z-dropdown);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: none;
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  padding: var(--space-xl) var(--space-xs);
  cursor: pointer;
  opacity: 0;
  transition: transform var(--transition-normal), opacity var(--transition-normal);
  align-items: center;
  justify-content: center;
}

.nav__toggle-tab--visible {
  transform: translateY(-50%) translateX(0);
  opacity: 1;
}

.nav__toggle-tab:hover {
  background: var(--color-hover);
  border-color: var(--color-accent);
}

.nav__toggle-icon {
  color: var(--color-muted);
  font-size: var(--text-xl);
  line-height: 1;
  transition: color var(--transition-fast);
}

.nav__toggle-tab:hover .nav__toggle-icon {
  color: var(--color-accent);
}

/* =========================================================================
   Responsive: sm (480px)
   ========================================================================= */

@media (min-width: 480px) {
  .nav {
    width: 280px;
    max-width: 85vw;
  }
}

/* =========================================================================
   Responsive: md (768px) — fixed sidebar
   ========================================================================= */

@media (min-width: 768px) {
  .nav {
    width: var(--nav-width);
    max-width: none;
    transform: translateX(0);
    box-shadow: none;
  }

  .nav--collapsed {
    transform: translateX(-100%);
    width: 0;
  }

  .nav--open {
    transform: translateX(0);
  }

  .nav__link {
    padding: var(--space-md) var(--space-lg);
    font-size: var(--text-sm);
    min-height: auto;
  }

  .nav__link--active {
    border-left-width: 2px;
  }

  .nav__header {
    padding: var(--space-md) var(--space-lg) var(--space-lg);
  }

  .nav__logo {
    font-size: 1.5rem;
  }

  .nav__footer {
    font-size: 0.55rem;
  }

  .nav__toggle-tab {
    display: flex;
  }

  .nav__backdrop {
    display: none !important;
  }
}

/* =========================================================================
   Responsive: lg (1024px)
   ========================================================================= */

@media (min-width: 1024px) {
  .nav {
    width: var(--nav-width);
  }
}

/* =========================================================================
   Responsive: xl (1280px)
   ========================================================================= */

@media (min-width: 1280px) {
  .nav {
    width: var(--nav-width);
  }
}

/* =========================================================================
   Print
   ========================================================================= */

@media print {
  .nav,
  .nav__backdrop,
  .nav__toggle-tab {
    display: none !important;
  }
}