.app-shell {
  min-height: 100vh;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 10;
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: 0 clamp(1.25rem, 4vw, 2rem);
  background: rgba(255, 255, 255, 0.97);
  border-bottom: 1px solid rgba(28, 33, 38, 0.07);
}

.app-logo {
  padding: 0;
  color: var(--color-text);
  background: transparent;
  border: 0;
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.025em;
}

.app-logo:hover {
  color: var(--color-primary-accessible);
}

.app-navigation {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.nav-button {
  min-height: 40px;
  padding: 0.55rem 0.8rem;
  color: var(--color-text-muted);
  background: transparent;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  transition:
    color var(--transition-fast),
    background-color var(--transition-fast),
    border-color var(--transition-fast);
}

.nav-button:hover {
  color: var(--color-text);
  background: var(--color-surface-soft);
}

.nav-button.is-active {
  color: var(--color-primary-accessible);
  background: var(--color-primary-soft);
}

.app-content {
  width: min(100% - 2rem, var(--container-width));
  margin: 0 auto;
  padding: clamp(2.5rem, 6vw, 4.5rem) 0;
}

.page-header {
  margin-bottom: var(--space-5);
}

.page-header h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 2.6rem);
  line-height: 1.1;
  letter-spacing: -0.045em;
}

.page-header p:not(.section-eyebrow) {
  max-width: 720px;
  margin: 0.8rem 0 0;
  color: var(--color-text-muted);
  line-height: 1.6;
}

@media (max-width: 700px) {
  .app-header {
    position: static;
    min-height: auto;
    align-items: flex-start;
    flex-direction: column;
    padding-top: var(--space-3);
    padding-bottom: var(--space-3);
  }

  .app-navigation {
    width: 100%;
    flex-wrap: wrap;
  }

  .nav-button {
    flex: 1 1 auto;
  }

  .app-navigation .button {
    flex: 1 1 100%;
  }
}

@media (max-width: 600px) {
  .app-content {
    width: min(100% - 1.5rem, var(--container-width));
    padding: 1.75rem 0 2.5rem;
  }
}