/* ═══════════════════════════════════════════
   LP TEACHER — Header
   ═══════════════════════════════════════════ */

.app-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--header-h);
  background: var(--bg-panel);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  display: flex;
  align-items: center;
  padding: 0 18px;
  gap: 14px;
  z-index: 200;
}

/* ── Brand ── */
.header-brand {
  display: flex;
  align-items: center;
  gap: 9px;
  text-decoration: none;
  flex-shrink: 0;
}

.header-brand-icon {
  width: 32px; height: 32px;
  background: var(--accent-grad);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  color: #fff;
  font-weight: 700;
}

.header-brand-name {
  font-size: 1.05rem;
  font-weight: 800;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

/* ── Divider ── */
.header-divider {
  width: 1px;
  height: 22px;
  background: var(--border);
  flex-shrink: 0;
}

/* ── Nav ── */
.header-nav {
  display: flex;
  align-items: center;
  gap: 3px;
}

.nav-btn {
  padding: 5px 13px;
  border-radius: var(--r-sm);
  border: 1.5px solid transparent;
  background: transparent;
  color: var(--text-sub);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--t-fast);
  display: flex;
  align-items: center;
  gap: 5px;
  white-space: nowrap;
}

.nav-btn:hover:not(:disabled) {
  background: var(--bg-hover);
  color: var(--text-body);
}

.nav-btn.active {
  background: var(--accent-light);
  color: var(--accent);
  border-color: var(--accent);
}

.nav-btn.coming-soon {
  opacity: 0.45;
  cursor: not-allowed;
  position: relative;
}

.nav-btn.coming-soon::after {
  content: 'soon';
  position: absolute;
  top: -7px; right: -5px;
  background: var(--amber);
  color: #fff;
  font-size: 0.56rem;
  font-weight: 800;
  padding: 1px 4px;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  pointer-events: none;
}

/* ── Spacer ── */
.header-spacer { flex: 1; }

/* ── Right actions ── */
.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.status-label { font-weight: 600; }

.theme-btn {
  width: 34px; height: 34px;
  border-radius: 50%;
  border: 1.5px solid var(--border);
  background: var(--bg-surface);
  color: var(--text-body);
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--t-fast);
}

.theme-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: var(--shadow-sm);
}