/* Responsibility: topbar, brand logo, nav links, footer. */

/* --- Topbar --- */
.topbar {
  position: sticky;
  top: var(--space-3);
  z-index: var(--z-sticky);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: 8px var(--space-4);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-size: var(--fs-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
  transition: opacity 0.15s var(--ease);
}

.brand-logo:hover {
  opacity: 0.7;
}

.nav {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: var(--radius-md);
  color: var(--muted);
  font-size: var(--fs-base);
  font-weight: 500;
  transition: var(--transition-fast);
}

.nav-link:hover {
  background: var(--surface-alt);
  color: var(--ink);
}

.nav-link.active {
  background: var(--surface-alt);
  color: var(--ink);
  font-weight: 600;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* --- Hamburger (mobile only) --- */
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  flex: 0 0 auto;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  background: var(--surface-alt);
  color: var(--ink);
  cursor: pointer;
  transition: var(--transition-fast);
}

.nav-toggle:hover {
  background: var(--surface-sunken);
}

@media (max-width: 640px) {
  .nav-toggle {
    display: inline-flex;
  }

  .nav {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    right: 0;
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding: var(--space-2);
    background: var(--surface);
    border: 1px solid var(--line);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-6px);
    transition: var(--transition);
  }

  .nav.is-open {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .nav-link {
    padding: 11px 12px;
  }

  /* Only the Start button is dropped on small screens — hiding .nav-actions
     would take the hamburger with it and leave no navigation at all. */
  .nav-actions .primary-btn {
    display: none;
  }

  body.nav-open .topbar {
    border-color: var(--line-strong);
  }
}

/* --- Footer --- */
.footer {
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--line);
  text-align: center;
  color: var(--muted);
  font-size: var(--fs-sm);
}

.footer .brand-logo {
  justify-content: center;
  margin-bottom: var(--space-3);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-5);
  margin-bottom: var(--space-3);
  font-size: var(--fs-base);
}

.footer-links a:hover {
  color: var(--ink);
}

.footer-copy {
  color: var(--muted-light);
  font-size: var(--fs-xs);
}