.app-header {
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 100;
  border-bottom: 1px solid var(--border);
}

.app-header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing);
  padding-left: max(var(--spacing), env(safe-area-inset-left));
  padding-right: max(var(--spacing), env(safe-area-inset-right));
}

.app-title-block {
  padding: 1.75rem 0 0.5rem;
}

.app-title {
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--text);
  line-height: 1.2;
}

.app-subtitle {
  font-size: 0.72rem;
  color: var(--text-tertiary);
  margin-top: 0.3rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.nav-tabs {
  display: flex;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  gap: 0;
  margin-top: 0.25rem;
}

.nav-tabs::-webkit-scrollbar { display: none; }

.nav-tab {
  position: relative;
  padding: 0.65rem 0;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  margin-right: 2rem;
  white-space: nowrap;
  cursor: pointer;
  border: none;
  background: none;
  font-family: var(--font);
  font-size: 0.82rem;
  font-weight: 400;
  color: var(--text-tertiary);
  border-bottom: 1.5px solid transparent;
  margin-bottom: -1px;
  transition: color 0.12s, border-color 0.12s;
  letter-spacing: 0.01em;
}

.nav-tab:hover { color: var(--text); }

.nav-tab.active {
  color: var(--text);
  border-bottom-color: var(--text);
  font-weight: 500;
}

/* Tab tooltips are hover-only: on touch, iOS sticky :hover would flash them
   over the page content after every tab tap. */
@media (hover: hover) and (pointer: fine) {
  .nav-tab::after {
    content: attr(data-tooltip);
    position: absolute;
    top: calc(100% + 6px);
    left: 50%;
    transform: translateX(-50%);
    background: var(--text);
    color: var(--bg);
    font-size: 0.72rem;
    font-weight: 400;
    white-space: nowrap;
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.15s;
    z-index: 200;
  }

  .nav-tab:hover::after { opacity: 1; }
}

@media (max-width: 640px) {
  .app-title-block { padding: 0.9rem 0 0.3rem; }
  .app-title { font-size: 0.92rem; }
  .app-subtitle { font-size: 0.68rem; margin-top: 0.1rem; }
}