/* ============================================================
   Nav — sticky top navigation with mobile hamburger
   ============================================================ */

.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: var(--z-nav);
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: rgba(11,18,32,0.55);
  backdrop-filter: blur(18px) saturate(140%);
  -webkit-backdrop-filter: blur(18px) saturate(140%);
  border-bottom: 1px solid transparent;
  transition: height var(--dur-base) var(--ease-out),
              background var(--dur-base) var(--ease-out),
              border-color var(--dur-base) var(--ease-out);
}
.nav.is-scrolled {
  height: var(--nav-h-shrink);
  background: rgba(11,18,32,0.85);
  border-bottom-color: var(--c-border-soft);
  box-shadow: var(--sh-md);
}

.nav-inner {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--sp-5);
  display: flex;
  align-items: center;
  gap: var(--sp-6);
}
@media (min-width: 768px) {
  .nav-inner { padding-inline: var(--sp-8); }
}

/* ---------- Logo ---------- */
.nav-logo {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-3);
  color: var(--c-text);
  font-family: var(--ff-display);
  font-weight: var(--fw-black);
  font-size: 1.125rem;
  letter-spacing: 0.02em;
  flex: 0 0 auto;
}
.nav-logo:hover { color: var(--c-text); }
.nav-logo-mark {
  width: 36px; height: 36px;
  border-radius: 10px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, var(--c-accent) 0%, #8B5CF6 100%);
  box-shadow: 0 4px 12px rgba(34,211,238,0.35);
}
.nav-logo-mark svg { width: 22px; height: 22px; color: var(--c-bg); }

/* ---------- Desktop links ---------- */
.nav-links {
  display: none;
  flex: 1;
  justify-content: center;
  gap: var(--sp-1);
  list-style: none;
  padding: 0;
  margin: 0;
}
.nav-links a {
  display: inline-block;
  padding: var(--sp-2) var(--sp-4);
  font-size: var(--fs-small);
  font-weight: var(--fw-medium);
  color: var(--c-text-2);
  border-radius: var(--r-md);
  transition: color var(--dur-fast), background var(--dur-fast);
}
.nav-links a:hover {
  color: var(--c-text);
  background: rgba(255,255,255,0.04);
}
.nav-links a.is-active {
  color: var(--c-accent);
  background: rgba(34,211,238,0.08);
}

@media (min-width: 1024px) {
  .nav-links { display: flex; }
}

/* ---------- Right side actions ---------- */
.nav-actions {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: var(--sp-3);
}
.nav-cta {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: 10px var(--sp-4);
  background: var(--c-line);
  color: #fff;
  font-weight: var(--fw-semibold);
  font-size: var(--fs-small);
  border-radius: var(--r-pill);
  transition: transform var(--dur-fast) var(--ease-out),
              box-shadow var(--dur-fast);
  box-shadow: 0 6px 16px rgba(6,199,85,0.35);
}
.nav-cta:hover {
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 8px 22px rgba(6,199,85,0.45);
}
.nav-cta svg { width: 16px; height: 16px; }

/* mobile：CTA 文字隱藏，只剩 icon 圓鈕 */
@media (max-width: 480px) {
  .nav-cta {
    padding: 0;
    width: 40px; height: 40px;
    border-radius: 50%;
    justify-content: center;
  }
  .nav-cta-text { display: none; }
}

/* ---------- Hamburger ---------- */
.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px; height: 40px;
  border-radius: var(--r-md);
  border: 1px solid var(--c-border-soft);
  color: var(--c-text);
  transition: background var(--dur-fast);
}
.nav-toggle:hover { background: rgba(255,255,255,0.04); }
.nav-toggle svg { width: 22px; height: 22px; }

@media (min-width: 1024px) {
  .nav-toggle { display: none; }
}

/* ---------- Mobile drawer ---------- */
.nav-drawer {
  position: fixed;
  inset: 0;
  z-index: calc(var(--z-nav) - 1);
  background: rgba(7,11,22,0.96);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: flex;
  flex-direction: column;
  padding: calc(var(--nav-h) + var(--sp-8)) var(--sp-6) var(--sp-8);
  opacity: 0;
  pointer-events: none;
  transform: translateY(-12px);
  transition: opacity var(--dur-base) var(--ease-out),
              transform var(--dur-base) var(--ease-out);
}
.nav-drawer.is-open {
  opacity: 1;
  pointer-events: auto;
  transform: none;
}
.nav-drawer ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
}
.nav-drawer a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--sp-4) var(--sp-3);
  font-size: 1.125rem;
  font-weight: var(--fw-semibold);
  color: var(--c-text);
  border-bottom: 1px solid var(--c-border-soft);
  transition: color var(--dur-fast);
}
.nav-drawer a:hover { color: var(--c-accent); }
.nav-drawer a::after {
  content: "›";
  color: var(--c-muted);
  font-weight: 400;
  font-size: 1.5rem;
}

@media (min-width: 1024px) {
  .nav-drawer { display: none; }
}

/* 鎖住背景捲動：當 drawer 開啟時 body 會被加 .nav-locked */
body.nav-locked { overflow: hidden; }