/* ─────────────────────────────────────────────────────
   FILE: nav.css
   Purpose: Sticky top nav with mobile hamburger.
   Used by both index.html and lab.html.
   Mobile menu uses CSS-only checkbox hack.
   ───────────────────────────────────────────────────── */

/* ── Container ─────────────────────────────────────── */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--color-border);
  transition: background var(--transition-base), border-color var(--transition-base);
}
.nav--scrolled {
  background: rgba(255, 255, 255, 0.97);
  border-bottom-color: var(--color-border-2);
}

.nav__inner {
  position: relative;            /* anchor for absolute toggle/burger */
  max-width: var(--max-width);
  margin: 0 auto;
  height: 100%;
  padding: 0 var(--space-8);
  display: flex;
  align-items: center;
  gap: var(--space-3);           /* uniform gap between items */
}

/* ── Logo ──────────────────────────────────────────── */
.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-right: auto;            /* push the rest of the bar right */
  flex-shrink: 0;
  white-space: nowrap;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: var(--tracking-snug);
  color: var(--color-text);
}
.nav__dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-accent);
}
.nav__dot--green  { background: var(--color-green); }
.nav__dot--orange { background: var(--color-orange); }

/* ── Links ─────────────────────────────────────────── */
.nav__links {
  display: flex;
  gap: 2px;
  align-items: center;
  flex-shrink: 0;                /* don't squeeze on cramped widths */
}
.nav__link {
  font-size: var(--text-base);
  color: var(--color-sub);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  letter-spacing: -0.01em;
  white-space: nowrap;           /* keep each link on one line */
  cursor: pointer;
  transition: color var(--transition-fast), background var(--transition-fast);
}
.nav__link:hover { color: var(--color-text); background: var(--color-bg-2); }
.nav__link.is-active { color: var(--color-text); background: var(--color-bg-2); }
.nav__link--accent  { color: var(--color-accent); }
.nav__link--accent:hover { background: var(--color-accent-bg); }
.nav__link--orange  { color: var(--color-orange); }
.nav__link--orange:hover { background: var(--color-orange-bg); }

/* ── CTA ───────────────────────────────────────────── */
.nav__cta {
  flex-shrink: 0;
  white-space: nowrap;
  background: var(--color-text);
  color: #fff;
  font-size: var(--text-sm);
  font-weight: 500;
  padding: 8px 16px;
  border-radius: var(--radius-md);
  letter-spacing: -0.01em;
  transition: opacity var(--transition-base);
}
.nav__cta:hover { opacity: 0.86; }

/* ── Mobile hamburger (CSS-only checkbox hack) ───────
   The checkbox is taken OUT of flex flow via absolute
   positioning so it can never add phantom gaps to the
   nav row, even when "hidden". The :checked state is
   still toggled by clicking the label. */
.nav__toggle {
  position: absolute;
  width: 0;
  height: 0;
  opacity: 0;
  pointer-events: none;
}
.nav__burger {
  display: none;
  width: 36px;
  height: 36px;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  border-radius: var(--radius-md);
  transition: background var(--transition-fast);
}
.nav__burger:hover { background: var(--color-bg-2); }
.nav__burger span {
  display: block;
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: var(--color-text);
  transition: transform var(--transition-base), opacity var(--transition-base);
}

/* ── Mobile / tablet breakpoint ─────────────────────
   Bumped from 600px to 768px so a 700–760-wide window
   no longer sits in a "squeezed desktop" no-man's land
   where 4 links + logo + CTA can clip off the edges. */
@media (max-width: 768px) {
  .nav__inner { padding: 0 var(--space-5); gap: var(--space-2); }
  .nav__cta   { display: none; }

  .nav__burger { display: flex; }

  .nav__links {
    /* Anchor at viewport top with padding to clear the nav row.
       translateY(-100%) then slides the WHOLE element fully off-
       screen — no slivers leaking back to cover the logo. */
    position: fixed;
    top: 0;
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: calc(var(--nav-height) + var(--space-3)) var(--space-3) var(--space-3);
    max-height: 100vh;
    overflow-y: auto;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-hover);
    transform: translateY(-100%);
    transition: transform 250ms ease, visibility 0s 250ms;
    z-index: 40;                 /* under the nav (50), above page */
    visibility: hidden;
  }
  .nav__links .nav__link {
    padding: 12px 14px;
    border-radius: var(--radius-md);
    font-size: var(--text-md);
  }

  .nav__toggle:checked ~ .nav__links {
    transform: translateY(0);
    visibility: visible;
    transition: transform 250ms ease, visibility 0s;
  }
  .nav__toggle:checked ~ .nav__burger span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
  .nav__toggle:checked ~ .nav__burger span:nth-child(2) { opacity: 0; }
  .nav__toggle:checked ~ .nav__burger span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }
}