/*
 * EnglishAI — unified navbar (authenticated zone), Mac-style top bar.
 * See docs/englishai_nav.md.
 *
 * All colors/shadows/radii/motion come from tokens.css. Nothing hard-coded.
 */

:root {
  --nav-h:   60px;
  --nav-h-m: 56px;
}

/* Reserve height so page content never jumps between loading/authed states. */
#app-nav { display: block; min-height: var(--nav-h); }
@media (max-width: 900px) { #app-nav { min-height: var(--nav-h-m); } }

/* ── Bar ─────────────────────────────────────────────────────────────── */

.eai-nav {
  position: sticky; top: 0; z-index: var(--z-nav);
  display: flex; align-items: center; justify-content: space-between;
  gap: 12px; padding: 0 24px; height: var(--nav-h);
  background: var(--glass-strong);
  -webkit-backdrop-filter: var(--blur);
          backdrop-filter: var(--blur);
  border-bottom: 1px solid var(--border);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  color: var(--text);
  transition: background var(--dur-med) var(--ease), border-color var(--dur-med) var(--ease);
}
@media (max-width: 900px) {
  .eai-nav { padding: 0 16px; height: var(--nav-h-m); }
}

/* ── Logo ────────────────────────────────────────────────────────────── */

.eai-nav-logo {
  display: flex; align-items: center; gap: 10px;
  text-decoration: none; color: inherit; flex-shrink: 0;
}
.eai-nav-mark {
  width: 30px; height: 30px; border-radius: var(--radius-sm);
  background: var(--brand-gradient);
  display: flex; align-items: center; justify-content: center;
  box-shadow: 0 4px 12px -4px rgba(59, 130, 246, .35), var(--shadow-1);
  position: relative;
}
.eai-nav-mark::after {
  content: ''; position: absolute; inset: 0; border-radius: inherit;
  background: linear-gradient(180deg, rgba(255,255,255,.20) 0%, transparent 45%);
  pointer-events: none;
}
.eai-nav-brand {
  font-weight: 700; font-size: 1rem;
  color: var(--text); letter-spacing: -0.02em;
}
.eai-nav-brand em {
  font-style: normal;
  background: var(--brand-gradient);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent; color: transparent;
}

/* ── Primary links (center) ──────────────────────────────────────────── */

.eai-nav-primary {
  display: flex; align-items: center; gap: 2px;
  flex: 1; justify-content: center; min-width: 0;
}
.eai-nav-link {
  position: relative;
  padding: 7px 14px; border-radius: var(--radius-sm);
  text-decoration: none; color: var(--text-2);
  font-weight: 500; font-size: .88rem; line-height: 1;
  transition: color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease);
  white-space: nowrap;
}
.eai-nav-link:hover { color: var(--text); background: var(--surface-hover); }
.eai-nav-link.active {
  color: var(--text); background: var(--surface-active);
  font-weight: 600;
}
.eai-nav-link .eai-nav-dot {
  display: inline-block; width: 6px; height: 6px; border-radius: 50%;
  background: var(--danger); margin-left: 6px; vertical-align: middle;
}
.eai-nav-link svg { display: none; } /* icons only used in sidebar variant */

/* ── Right cluster ───────────────────────────────────────────────────── */

.eai-nav-right {
  display: flex; align-items: center; gap: 8px; flex-shrink: 0;
}
.eai-nav-extras { display: flex; align-items: center; gap: 6px; }
.eai-nav-extras:empty { display: none; }
.eai-nav-utility { display: contents; }

/* Language pill */
.eai-lang {
  display: flex; align-items: center; gap: 2px;
  background: var(--surface-2); border-radius: var(--radius-sm); padding: 2px;
  border: 1px solid var(--border);
}
.eai-lang-b {
  padding: 4px 10px; border-radius: 6px; border: 0; background: transparent;
  font-family: inherit; font-size: .72rem; font-weight: 600;
  color: var(--text-2); cursor: pointer;
  transition: color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease);
  letter-spacing: .05em;
}
.eai-lang-b.active {
  background: var(--surface); color: var(--text);
  box-shadow: var(--shadow-1);
}
.eai-lang-b:hover:not(.active) { color: var(--text); }

/* Theme toggle */
.eai-theme-btn {
  width: 32px; height: 32px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: var(--surface);
  color: var(--text-2); cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: background var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.eai-theme-btn:hover { background: var(--surface-hover); color: var(--text); border-color: var(--border-strong); }
.eai-theme-btn:focus-visible { outline: none; box-shadow: var(--shadow-focus); border-color: var(--brand); }
.eai-theme-btn svg { width: 16px; height: 16px; display: block; }

/* Streak pill */
.eai-nav-streak {
  display: inline-flex; align-items: center; gap: 4px;
  padding: 4px 10px; border-radius: var(--radius-round);
  background: var(--warn-bg); color: var(--warn);
  border: 1px solid transparent;
  font-size: .8rem; line-height: 1; font-weight: 600;
  flex-shrink: 0;
}
.eai-nav-streak b { font-weight: 700; }
@media (max-width: 640px) { .eai-nav-streak { padding: 3px 8px; font-size: .75rem; } }

/* Login button (guest) — tech gradient CTA */
.eai-nav-login {
  padding: 7px 18px; border-radius: var(--radius-sm);
  background: var(--brand-gradient); background-size: 200% 100%;
  background-position: 0% 50%;
  color: #ffffff; border: 0;
  font: inherit; font-weight: 600; font-size: .85rem;
  text-decoration: none; cursor: pointer;
  transition: background-position var(--dur-med) var(--ease),
              transform var(--dur-fast) var(--ease),
              box-shadow var(--dur-fast) var(--ease);
  box-shadow: 0 4px 14px -4px rgba(59, 130, 246, .45), var(--shadow-1);
}
.eai-nav-login:hover {
  background-position: 100% 50%;
  box-shadow: 0 8px 22px -6px rgba(59, 130, 246, .55), var(--shadow-2);
}
.eai-nav-login:active { transform: scale(.98); }

/* Skeleton (loading) */
.eai-nav-skel {
  width: 32px; height: 32px; border-radius: 50%;
  background: linear-gradient(90deg, var(--surface-2) 25%, var(--surface-hover) 50%, var(--surface-2) 75%);
  background-size: 200% 100%;
  animation: eai-nav-shimmer 1.2s linear infinite;
}
@keyframes eai-nav-shimmer { 0% { background-position: 200% 0; } 100% { background-position: -200% 0; } }

/* ── Avatar chip + dropdown (opens DOWN from chip on top-right) ───────── */

.eai-nav-menu-wrap { position: relative; }

.eai-nav-chip {
  display: flex; align-items: center; gap: 6px;
  padding: 3px 10px 3px 3px;
  border: 1px solid var(--border); border-radius: var(--radius-round);
  background: var(--surface); cursor: pointer; font: inherit;
  color: var(--text); font-size: .78rem; font-weight: 600;
  transition: border-color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease);
}
.eai-nav-chip:hover { border-color: var(--border-strong); background: var(--surface-hover); }
.eai-nav-chip[aria-expanded="true"] { border-color: var(--brand); }
.eai-nav-chip:focus-visible { outline: none; box-shadow: var(--shadow-focus); border-color: var(--brand); }
.eai-nav-chip-name {
  max-width: 110px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.eai-nav-chip-caret { width: 12px; height: 12px; opacity: .5; flex-shrink: 0; }
@media (max-width: 700px) { .eai-nav-chip-name, .eai-nav-chip-caret { display: none; } }

.eai-nav-menu {
  position: absolute; top: calc(100% + 8px); right: 0;
  min-width: 240px;
  background: var(--glass-strong);
  -webkit-backdrop-filter: var(--blur); backdrop-filter: var(--blur);
  border: 1px solid var(--border); border-radius: var(--radius-lg);
  box-shadow: var(--shadow-3);
  padding: 6px; z-index: calc(var(--z-nav) + 10);
  display: none;
  transform-origin: top right;
  animation: eai-menu-in var(--dur-med) var(--ease);
}
.eai-nav-menu.open { display: block; }
@keyframes eai-menu-in {
  from { opacity: 0; transform: translateY(-4px) scale(.98); }
  to   { opacity: 1; transform: translateY(0)   scale(1); }
}

.eai-nav-menu-head {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 10px 12px; border-bottom: 1px solid var(--border);
  margin-bottom: 4px;
}
.eai-nav-menu-head .ava { width: 40px; height: 40px; border-radius: 50%; overflow: hidden;
                          display: flex; align-items: center; justify-content: center;
                          color: #fff; font-weight: 700; flex-shrink: 0; font-size: .95rem; }
.eai-nav-menu-head .ava img { width: 100%; height: 100%; object-fit: cover; display: block; }
.eai-nav-menu-head-txt { min-width: 0; }
.eai-nav-menu-name { font-weight: 600; font-size: .92rem; color: var(--text);
                     overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.eai-nav-menu-login { font-size: .76rem; color: var(--text-2); margin-top: 2px;
                      overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }

.eai-role-badge {
  display: inline-block; padding: 2px 8px; border-radius: var(--radius-sm);
  font-size: .66rem; font-weight: 700; margin-top: 4px;
  text-transform: uppercase; letter-spacing: .04em;
}
.eai-role-student  { background: var(--brand-tint); color: var(--brand-2); }
.eai-role-teacher  { background: var(--info-bg);    color: var(--brand-2); }
.eai-role-admin    { background: var(--warn-bg);    color: var(--warn); }

.eai-nav-menu-item {
  display: flex; align-items: center; gap: 10px;
  padding: 9px 12px; border-radius: var(--radius-sm);
  text-decoration: none; color: var(--text-2);
  font: inherit; font-size: .88rem; background: transparent;
  border: 0; width: 100%; cursor: pointer; text-align: left;
  transition: background var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.eai-nav-menu-item:hover { background: var(--surface-hover); color: var(--text); }
.eai-nav-menu-item.active { background: var(--brand-tint); color: var(--text); font-weight: 600; }
.eai-nav-menu-item.danger { color: var(--danger); }
.eai-nav-menu-item.danger:hover { background: var(--danger-bg); }
.eai-nav-menu-item svg { flex-shrink: 0; opacity: .75; width: 16px; height: 16px; }
.eai-nav-menu-item.active svg { opacity: 1; color: var(--brand-2); }
.eai-nav-menu-sep { height: 1px; background: var(--border); margin: 4px 4px; }

/* Locked state (must_change_password) — logo + language + logout only */
.eai-nav.locked .eai-nav-primary { display: none; }

/* ── Mobile: hamburger + drawer ──────────────────────────────────────── */

.eai-nav-burger {
  display: none; width: 36px; height: 36px;
  border: 1px solid var(--border); border-radius: var(--radius-sm);
  background: var(--surface); cursor: pointer; color: var(--text);
  align-items: center; justify-content: center; padding: 0;
  transition: background var(--dur-fast) var(--ease);
}
.eai-nav-burger:hover { background: var(--surface-hover); }
.eai-nav-burger svg { display: block; }

@media (max-width: 900px) {
  .eai-nav-burger { display: inline-flex; }
  .eai-nav-primary { display: none; }
  .eai-nav-chip, .eai-nav-menu-wrap { display: none; }
  .eai-nav-extras { display: none; }
  /* Theme toggle stays visible on mobile — quick 1-tap switch instead of
     having to open the drawer just to flip dark/light. */
  .eai-nav-streak { display: none; }
  .eai-nav-right { gap: 8px; }
}

.eai-drawer-back {
  position: fixed; inset: 0; background: rgba(0, 0, 0, .45);
  z-index: var(--z-drawer); opacity: 0; pointer-events: none;
  transition: opacity var(--dur-med) var(--ease);
  -webkit-backdrop-filter: blur(2px); backdrop-filter: blur(2px);
}
.eai-drawer-back.open { opacity: 1; pointer-events: auto; }

.eai-drawer {
  position: fixed; top: 0; right: 0; bottom: 0;
  width: 88%; max-width: 340px;
  background: var(--surface);
  border-left: 1px solid var(--border);
  box-shadow: var(--shadow-3);
  z-index: calc(var(--z-drawer) + 1); transform: translateX(100%);
  transition: transform var(--dur-slow) var(--ease);
  display: flex; flex-direction: column;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  color: var(--text);
}
.eai-drawer.open { transform: translateX(0); }

.eai-drawer-head {
  padding: 20px 22px 16px;
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center; gap: 12px;
}
.eai-drawer-head .ava { width: 44px; height: 44px; border-radius: 50%; overflow: hidden;
                        display: flex; align-items: center; justify-content: center;
                        color: #fff; font-weight: 700; flex-shrink: 0; }
.eai-drawer-head .ava img { width: 100%; height: 100%; object-fit: cover; display: block; }

.eai-drawer-close {
  position: absolute; top: 16px; right: 16px;
  width: 32px; height: 32px; border-radius: var(--radius-sm);
  border: 1px solid var(--border); background: var(--surface); cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  color: var(--text-2);
}
.eai-drawer-close:hover { background: var(--surface-hover); color: var(--text); }

.eai-drawer-body { padding: 14px 12px; overflow-y: auto; flex: 1; }
.eai-drawer-section { padding: 10px 4px 6px; font-size: .68rem;
                      color: var(--text-3); font-weight: 700;
                      text-transform: uppercase; letter-spacing: .08em; }
.eai-drawer-item {
  display: flex; align-items: center; gap: 12px;
  padding: 11px 14px; border-radius: var(--radius-sm);
  text-decoration: none; color: var(--text);
  font: inherit; font-size: .95rem; background: transparent;
  border: 0; width: 100%; cursor: pointer; text-align: left;
  transition: background var(--dur-fast) var(--ease);
}
.eai-drawer-item:hover, .eai-drawer-item.active { background: var(--surface-hover); }
.eai-drawer-item.active { color: var(--text); font-weight: 600; }
.eai-drawer-item.danger { color: var(--danger); }
.eai-drawer-item.danger:hover { background: var(--danger-bg); }
.eai-drawer-sep { height: 1px; background: var(--border); margin: 8px 6px; }
.eai-drawer-lang, .eai-drawer-theme {
  display: flex; padding: 8px 14px; align-items: center; gap: 12px;
  justify-content: space-between;
}

@media (prefers-reduced-motion: reduce) {
  .eai-drawer, .eai-drawer-back, .eai-nav-menu { transition: none; animation: none; }
  .eai-nav-skel { animation: none; }
}