/* Navegación translúcida */

.nav {
  position: fixed;
  inset: 0 0 auto;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(251, 250, 247, 0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  box-shadow: 0 1px 0 transparent;
  transition: background-color 400ms ease, box-shadow 400ms ease;
}
.nav.is-scrolled { box-shadow: 0 1px 0 var(--line); }
.nav.is-dark { background: rgba(3, 24, 42, 0.62); box-shadow: 0 1px 0 rgba(255, 255, 255, 0.06); }
.nav.is-dark .nav__links a { color: rgba(245, 245, 247, 0.82); }
.nav.is-dark .nav__links a:hover { color: #fff; }
.nav.is-dark .nav__toggle span { background: var(--text-light); }
.nav.is-dark .nav__brand img { filter: brightness(0) invert(1); }

.nav__inner {
  max-width: calc(var(--max) + 2 * var(--gutter));
  height: 100%;
  margin: 0 auto;
  padding: 0 var(--gutter);
  display: flex;
  align-items: center;
  gap: 32px;
}
.nav__brand img { height: 21px; width: auto; transition: filter 400ms ease; }
.nav__links {
  display: flex;
  gap: 30px;
  margin-left: auto;
  font-size: 0.8125rem;
  letter-spacing: 0.005em;
}
.nav__links a { color: rgba(29, 29, 31, 0.78); transition: color 200ms ease; }
.nav__links a:hover { color: var(--navy); }

.nav__toggle {
  display: none;
  width: 44px;
  height: 44px;
  margin: 0 -12px 0 auto;
  padding: 0;
  border: 0;
  background: none;
  cursor: pointer;
  position: relative;
}
.nav__toggle span {
  position: absolute;
  left: 13px;
  width: 18px;
  height: 1.5px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 320ms var(--ease-out), background-color 400ms ease;
}
.nav__toggle span:first-child { top: 18px; }
.nav__toggle span:last-child { top: 25px; }
.nav__toggle[aria-expanded="true"] span:first-child { transform: translateY(3.5px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] span:last-child { transform: translateY(-3.5px) rotate(-45deg); }

@media (max-width: 760px) {
  .nav__toggle { display: block; }
  .nav__links {
    position: absolute;
    top: var(--nav-h);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    margin: 0;
    padding: 8px var(--gutter) 28px;
    font-size: 1.5rem;
    font-weight: 600;
    letter-spacing: -0.015em;
    background: rgba(251, 250, 247, 0.95);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    transform: translateY(-8px);
    opacity: 0;
    visibility: hidden;
    transition: opacity 220ms var(--ease-in), transform 220ms var(--ease-in), visibility 0s 220ms;
  }
  .nav__links a { padding: 10px 0; color: var(--text); }
  .nav.is-dark .nav__links { background: rgba(3, 24, 42, 0.95); }
  .nav.is-open .nav__links {
    opacity: 1;
    visibility: visible;
    transform: none;
    transition: opacity 320ms var(--ease-out), transform 320ms var(--ease-out), visibility 0s;
  }
}

/* Pila de paneles: el top lo calcula js/core/layout.js */

.stack { position: relative; }

.panel {
  position: sticky;
  top: 0;
  min-height: 100vh;
  min-height: 100svh;
  overflow: clip;
  isolation: isolate;
  transform-origin: 50% 50%;
  border-radius: var(--ra, 0) var(--ra, 0) var(--rb, 0) var(--rb, 0);
  box-shadow: 0 -24px 60px -20px rgba(0, 0, 0, var(--lift, 0));
}
.panel::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 20;
  background: #000;
  opacity: var(--shade, 0);
  pointer-events: none;
}
.panel[data-theme="light"] { background: var(--bg); }
.panel[data-theme="dark"] { background: var(--deep); color: var(--text-light); }

.panel__body {
  position: relative;
  width: 100%;
  max-width: calc(var(--max) + 2 * var(--gutter));
  margin: 0 auto;
  padding: calc(var(--nav-h) + clamp(48px, 10vh, 120px)) var(--gutter) clamp(64px, 12vh, 140px);
}

@media (prefers-reduced-transparency: reduce) {
  .nav, .nav__links { backdrop-filter: none; -webkit-backdrop-filter: none; background: var(--bg) !important; }
  .nav.is-dark, .nav.is-dark .nav__links { background: var(--deep) !important; }
}

@media (prefers-contrast: more) {
  .nav { background: var(--bg); box-shadow: 0 1px 0 rgba(0, 0, 0, 0.4); }
}