:root {
  --ink: #171411;
  --ink-soft: #24201c;
  --paper: #f3eddf;
  --paper-dim: #d8cdbb;
  --gold: #c7a96f;
  --gold-bright: #f0d59d;
  --orange: #f7941d;
  --blue: #25245d;
  --line: rgba(243, 237, 223, 0.18);
  --max: 1440px;
  --radius: 2px;
  --shadow: 0 30px 70px rgba(0,0,0,.28);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  background: var(--ink);
}

body {
  margin: 0;
  color: var(--paper);
  background:
    radial-gradient(circle at 50% 0%, rgba(199,169,111,.08), transparent 30rem),
    var(--ink);
  font-family: "DM Sans", system-ui, sans-serif;
  line-height: 1.6;
}

img { max-width: 100%; display: block; }
a { color: inherit; }

.skip-link {
  position: fixed;
  left: 1rem;
  top: -5rem;
  z-index: 999;
  padding: .75rem 1rem;
  background: var(--paper);
  color: var(--ink);
}
.skip-link:focus { top: 1rem; }

.hero {
  position: relative;
  min-height: 100svh;
  overflow: hidden;
  display: grid;
  align-items: end;
  isolation: isolate;
}

.hero__media {
  position: absolute;
  inset: 0;
  z-index: -3;
  background:
    url("assets/cabecera-libro.jpg") center top / cover no-repeat,
    linear-gradient(#6f5c48, #1b1713);
  transform: scale(1.03);
}

.hero__veil {
  position: absolute;
  inset: 0;
  z-index: -2;
  background:
    linear-gradient(to bottom, rgba(10,8,6,.15) 0%, rgba(10,8,6,.18) 35%, rgba(10,8,6,.82) 82%, var(--ink) 100%),
    radial-gradient(circle at 50% 40%, transparent 0 18%, rgba(15,12,9,.34) 62%);
}

.particles {
  position: absolute;
  inset: 0;
  z-index: -1;
  opacity: .6;
  background-image:
    radial-gradient(circle, rgba(255,243,194,.9) 0 1px, transparent 1.5px),
    radial-gradient(circle, rgba(240,213,157,.65) 0 1.2px, transparent 1.8px);
  background-size: 64px 64px, 103px 103px;
  background-position: 0 0, 23px 41px;
  mask-image: linear-gradient(to bottom, transparent 10%, #000 40%, #000 75%, transparent);
  animation: drift 18s linear infinite;
}

@keyframes drift {
  to { background-position: 64px 92px, -80px 145px; }
}

.topbar {
  position: absolute;
  top: 0;
  left: 50%;
  width: min(calc(100% - 2rem), var(--max));
  transform: translateX(-50%);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.25rem 0;
  z-index: 4;
  border-bottom: 1px solid rgba(255,255,255,.14);
}

.brand {
  display: inline-flex;
  gap: .75rem;
  align-items: center;
  text-decoration: none;
  font-weight: 600;
}

.brand__mark {
  display: grid;
  place-items: center;
  width: 2.25rem;
  aspect-ratio: 1;
  border: 2px solid var(--orange);
  border-radius: 50%;
  font-family: Georgia, serif;
  color: var(--orange);
}

.topbar__links {
  display: flex;
  gap: 1.75rem;
}

.topbar__links a {
  text-decoration: none;
  font-size: .92rem;
}
.topbar__links a:hover { color: var(--gold-bright); }

.menu-toggle {
  display: none;
  background: none;
  color: inherit;
  border: 1px solid rgba(255,255,255,.3);
  padding: .55rem .75rem;
}

.hero__content {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
  padding: 10rem 0 7rem;
  text-align: center;
}

.eyebrow,
.talk__meta,
.section__label {
  text-transform: uppercase;
  letter-spacing: .15em;
  font-size: .76rem;
  font-weight: 700;
  color: var(--gold-bright);
}

.hero h1 {
  margin: 1rem auto 1.5rem;
  max-width: 1100px;
  font-family: "Special Elite", Georgia, serif;
  font-size: clamp(3rem, 8vw, 8rem);
  line-height: .92;
  font-weight: 400;
  text-wrap: balance;
}

.hero h1 span {
  display: block;
  margin-bottom: .8rem;
  font-family: "DM Sans", sans-serif;
  font-size: .15em;
  text-transform: uppercase;
  letter-spacing: .28em;
  font-weight: 600;
}

.hero__date {
  margin: 0 0 2rem;
  color: var(--paper-dim);
  font-size: 1.05rem;
}

.hero__cta {
  display: inline-flex;
  gap: .85rem;
  align-items: center;
  padding: .9rem 1.2rem;
  border: 1px solid rgba(255,255,255,.4);
  text-decoration: none;
  backdrop-filter: blur(6px);
}
.hero__cta:hover { background: var(--paper); color: var(--ink); }

.section {
  width: min(calc(100% - 2rem), var(--max));
  margin-inline: auto;
}

.intro {
  padding: 8rem 0;
}

.intro__grid {
  display: grid;
  grid-template-columns: 1.25fr .75fr;
  gap: 5rem;
  align-items: start;
}

.intro h2 {
  margin: 1rem 0 0;
  font-family: "Special Elite", Georgia, serif;
  font-weight: 400;
  line-height: 1.08;
  font-size: clamp(2.2rem, 4vw, 5rem);
}

.intro__copy {
  color: var(--paper-dim);
  font-size: 1.05rem;
}

.index-strip {
  position: sticky;
  top: 0;
  z-index: 30;
  background: rgba(23,20,17,.88);
  border-block: 1px solid var(--line);
  backdrop-filter: blur(14px);
}

.index-strip__inner {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 2rem;
  min-height: 64px;
}

.index-strip__title {
  color: var(--gold-bright);
  text-transform: uppercase;
  letter-spacing: .12em;
  font-size: .75rem;
}

.index-strip__links {
  display: flex;
  gap: .35rem;
  overflow-x: auto;
  scrollbar-width: none;
}
.index-strip__links::-webkit-scrollbar { display: none; }

.index-strip__links a {
  min-width: 2.5rem;
  padding: .45rem .55rem;
  text-align: center;
  text-decoration: none;
  border: 1px solid transparent;
}
.index-strip__links a:hover,
.index-strip__links a.is-active {
  border-color: var(--gold);
  color: var(--gold-bright);
}

.talks {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
}

.talk {
  position: relative;
  display: grid;
  grid-template-columns: minmax(260px, .72fr) 1.28fr;
  gap: clamp(2rem, 6vw, 7rem);
  align-items: center;
  padding: 9rem 0;
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 90px;
}

.talk--reverse {
  grid-template-columns: 1.28fr minmax(260px, .72fr);
}
.talk--reverse .talk__portrait { grid-column: 2; }
.talk--reverse .talk__content { grid-column: 1; grid-row: 1; }

.talk__number {
  position: absolute;
  top: 3.8rem;
  right: 0;
  z-index: -1;
  font-family: Georgia, serif;
  font-weight: 700;
  font-size: clamp(7rem, 18vw, 18rem);
  line-height: .7;
  color: rgba(243,237,223,.055);
}

.talk__portrait {
  position: relative;
}
.talk__portrait::before {
  content: "";
  position: absolute;
  inset: 1rem -1rem -1rem 1rem;
  border: 1px solid var(--gold);
  z-index: -1;
}
.talk__portrait img {
  aspect-ratio: 4/5;
  width: 100%;
  object-fit: cover;
  filter: grayscale(1) sepia(.25) contrast(1.04);
  box-shadow: var(--shadow);
}

.talk__content h2 {
  margin: .4rem 0 .6rem;
  font-family: "Special Elite", Georgia, serif;
  font-weight: 400;
  font-size: clamp(2rem, 4vw, 4.6rem);
  line-height: 1.04;
  text-wrap: balance;
}

.talk__speaker {
  margin: 0 0 1.3rem;
  color: var(--gold-bright);
  font-weight: 600;
}

.talk__summary {
  max-width: 70ch;
  color: var(--paper-dim);
  margin-bottom: 2rem;
}

.video {
  position: relative;
  width: 100%;
  aspect-ratio: 16/9;
  background:
    linear-gradient(135deg, rgba(199,169,111,.18), rgba(37,36,93,.18)),
    #0c0a09;
  border: 1px solid rgba(255,255,255,.16);
  overflow: hidden;
}

.video__poster {
  position: absolute;
  inset: 0;
  border: 0;
  width: 100%;
  cursor: pointer;
  color: var(--paper);
  background:
    linear-gradient(to top, rgba(0,0,0,.8), rgba(0,0,0,.15)),
    url("assets/cabecera-libro.jpg") center / cover;
}

.video__poster::after {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(20,16,12,.45);
  transition: background .25s ease;
}
.video__poster:hover::after { background: rgba(20,16,12,.25); }

.video__play,
.video__hint {
  position: relative;
  z-index: 1;
}

.video__play {
  display: grid;
  place-items: center;
  width: 4.6rem;
  aspect-ratio: 1;
  margin: auto;
  border: 1px solid rgba(255,255,255,.7);
  border-radius: 50%;
  background: rgba(0,0,0,.25);
  font-size: 1.25rem;
  padding-left: .2rem;
}

.video__hint {
  position: absolute;
  left: 1rem;
  bottom: 1rem;
  text-transform: uppercase;
  letter-spacing: .12em;
  font-size: .72rem;
}

.video iframe {
  width: 100%;
  height: 100%;
  border: 0;
}

.footer {
  width: min(calc(100% - 2rem), var(--max));
  margin: 0 auto;
  padding: 5rem 0;
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  color: var(--paper-dim);
}

.footer__title {
  margin: 0;
  color: var(--paper);
  font-family: "Special Elite", Georgia, serif;
  font-size: 1.6rem;
}

.footer__links {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
}
.footer a { text-underline-offset: .25em; }

@media (max-width: 900px) {
  .intro__grid,
  .talk,
  .talk--reverse {
    grid-template-columns: 1fr;
  }

  .talk--reverse .talk__portrait,
  .talk--reverse .talk__content {
    grid-column: auto;
    grid-row: auto;
  }

  .talk__portrait {
    width: min(78%, 460px);
  }

  .talk--reverse .talk__portrait {
    margin-left: auto;
  }

  .topbar__links {
    position: absolute;
    top: calc(100% + .5rem);
    right: 0;
    display: none;
    flex-direction: column;
    min-width: 220px;
    padding: 1rem;
    background: rgba(23,20,17,.96);
    border: 1px solid var(--line);
  }
  .topbar__links.is-open { display: flex; }
  .menu-toggle { display: block; }
}

@media (max-width: 600px) {
  .brand__text { display: none; }
  .hero__content { padding-bottom: 4rem; }
  .intro { padding: 5rem 0; }
  .intro__grid { gap: 2rem; }
  .talk { padding: 6rem 0; }
  .talk__portrait { width: 88%; }
  .talk__number { top: 2rem; }
  .index-strip__title { display: none; }
  .footer { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .particles { animation: none; }
}