/*
 * nav.css
 * ─────────────────────────────────────────────────────────
 * LEARNER NOTE:
 * The top navigation bar switches between sections.
 * The .active class is toggled by JS (nav.js).
 * The animated underline uses a pseudo-element + transform.
 * ─────────────────────────────────────────────────────────
 */

.top-nav {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--clr-border);
  padding: 0 var(--sp-5);
  background: var(--clr-surface);
  flex-shrink: 0; /* Don't let nav shrink */
}

.nav-link {
  position: relative;
  font-family: var(--font-display);
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--clr-text-muted);
  padding: var(--sp-4) var(--sp-3);
  letter-spacing: 0.02em;
  transition: color var(--dur-base) var(--ease-smooth);

  /* The underline indicator */
  &::after {
    content: '';
    position: absolute;
    bottom: -1px; /* Sits on the border-bottom line */
    left: 0;
    right: 0;
    height: 2px;
    background: var(--clr-accent);
    border-radius: var(--radius-full);
    transform: scaleX(0);
    transform-origin: center;
    transition: transform var(--dur-base) var(--ease-smooth);
  }
}

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

html.light-mode .nav-link {
  color: #5a5a70;
}

html.light-mode .nav-link:hover {
  color: #1a1a2e;
}

html.light-mode .nav-link.active {
  color: #5a52e0;
}

/* Active state */
.nav-link.active {
  color: var(--clr-accent);
}

.nav-link.active::after {
  transform: scaleX(1);
}

/* ── Responsive: allow nav to scroll horizontally ── */
@media (max-width: 560px) {
  .top-nav {
    overflow-x: auto;
    padding: 0 var(--sp-3);
    scrollbar-width: none;
  }
  .top-nav::-webkit-scrollbar { display: none; }

  .nav-link {
    white-space: nowrap;
    padding: var(--sp-3) var(--sp-2);
  }
}

/* ── Theme Toggle (Switch) ── */
.top-nav .theme-toggle {
  background: transparent;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  overflow: visible;
  margin-left: auto;
  margin-top: 10px;
}

.top-nav .toggle-track {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 60px;
  height: 30px;
  background: var(--clr-surface-2);
  border: 1px solid var(--clr-border);
  border-radius: var(--radius-full);
  padding: 2px;
  position: relative;
  transition: all var(--dur-base) var(--ease-smooth);
  overflow: visible;
}

.top-nav .theme-toggle:hover .toggle-track {
  border-color: var(--clr-accent);
  box-shadow: 0 0 12px var(--clr-accent-glow);
}

html.light-mode .toggle-track {
  background: #1a1a2e;
  border-color: #5a52e0;
}

.side-icon {
  position: absolute;
  transition: opacity var(--dur-base) var(--ease-smooth), transform var(--dur-base) var(--ease-bounce);
  pointer-events: none;
}

.sun-side {
  left: 8px;
  color: #f59e0b;
  opacity: 0;
  transform: scale(0.6);
}

.moon-side {
  right: 8px;
  color: #818cf8;
  opacity: 1;
  transform: scale(1);
}

html.light-mode .sun-side {
  opacity: 1;
  transform: scale(1);
}

html.light-mode .moon-side {
  opacity: 0;
  transform: scale(0.6);
}

.toggle-thumb {
  position: absolute;
  left: 4px;
  width: 20px;
  height: 20px;
  background: var(--clr-accent);
  border-radius: 50%;
  transition: transform var(--dur-base) var(--ease-bounce), background var(--dur-base) var(--ease-smooth);
  box-shadow: 0 2px 8px rgba(0,0,0,0.3);
}

html.light-mode .toggle-thumb {
  transform: translateX(28px);
  background: #f59e0b;
}