:root {
  --ink: #201b16;
  --muted: #6b5f52;
  --paper: #f6efe1;
  --paper-deep: #eadcc4;
  --ivory: #fffaf0;
  --board: #17231d;
  --board-soft: #23392f;
  --chalk: #f3ecd8;
  --copper: #a45d2a;
  --copper-dark: #703918;
  --gold: #c99b4f;
  --line: rgba(32, 27, 22, 0.16);
  --shadow: 0 18px 48px rgba(32, 27, 22, 0.18);
  --radius: 8px;
  --content: 1120px;
  color-scheme: light;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: Georgia, "Times New Roman", serif;
  line-height: 1.55;
  overflow-x: hidden;
}

img,
svg {
  max-width: 100%;
}

a {
  color: inherit;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: 0.5rem;
  z-index: 20;
  transform: translateY(-140%);
  background: var(--ivory);
  color: var(--ink);
  padding: 0.6rem 0.8rem;
  border: 2px solid var(--ink);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(246, 239, 225, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.nav {
  width: min(var(--content), calc(100% - 1.5rem));
  margin: 0 auto;
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  font-weight: 700;
  text-decoration: none;
  letter-spacing: 0;
  white-space: nowrap;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  overflow-x: auto;
  scrollbar-width: none;
}

.nav-links::-webkit-scrollbar {
  display: none;
}

.nav-links a {
  text-decoration: none;
  color: var(--muted);
  font-family: Arial, Helvetica, sans-serif;
  font-size: 0.9rem;
  padding: 0.55rem 0.65rem;
  border-radius: 999px;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a:focus-visible {
  color: var(--ink);
  background: rgba(164, 93, 42, 0.12);
}

.hero {
  position: relative;
  min-height: calc(100vh - 64px);
  display: grid;
  align-items: end;
  isolation: isolate;
  color: var(--chalk);
  background: var(--board);
}

.hero-media,
.hero-overlay {
  position: absolute;
  inset: 0;
}

.hero-media {
  background-image: url("assets/serre-grothendieck-etale-hero.png");
  background-size: cover;
  background-position: 48% center;
  z-index: -3;
}

.hero-overlay {
  z-index: -2;
  background:
    linear-gradient(90deg, rgba(13, 18, 15, 0.91), rgba(13, 18, 15, 0.68) 48%, rgba(13, 18, 15, 0.26)),
    linear-gradient(0deg, rgba(13, 18, 15, 0.72), rgba(13, 18, 15, 0.16) 55%, rgba(13, 18, 15, 0.42));
}

.hero-content {
  width: min(780px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 5rem 0 2.25rem;
}

.eyebrow {
  margin: 0 0 0.75rem;
  color: var(--copper-dark);
  font-family: Arial, Helvetica, sans-serif;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.hero .eyebrow {
  color: var(--gold);
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1,
h2,
h3 {
  line-height: 1.08;
  letter-spacing: 0;
}

h1 {
  max-width: 11ch;
  margin: 0;
  font-size: clamp(3rem, 10vw, 6.8rem);
}

h2 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 4rem);
}

h3 {
  margin: 0;
  font-size: 1.3rem;
}

.lede {
  margin: 1rem 0 0.75rem;
  font-size: clamp(1.25rem, 4vw, 2rem);
}

.hero p:not(.eyebrow):not(.lede):not(.caption) {
  max-width: 62ch;
  color: rgba(243, 236, 216, 0.92);
  font-size: 1.08rem;
}

.hero-actions,
.link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
}

.hero-actions {
  margin: 1.5rem 0 1rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  padding: 0.75rem 1rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-family: Arial, Helvetica, sans-serif;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
}

.button.primary {
  color: var(--ivory);
  background: var(--copper-dark);
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.18);
}

.button.primary:hover,
.button.primary:focus-visible {
  background: #5d2f14;
}

.button.secondary {
  color: var(--chalk);
  border-color: rgba(243, 236, 216, 0.5);
  background: rgba(243, 236, 216, 0.09);
}

.simple-page .button.secondary,
.privacy-card .button.secondary {
  color: var(--ink);
  border-color: var(--line);
  background: var(--ivory);
}

.schedule-note {
  display: inline-grid;
  gap: 0.15rem;
  margin: 0.2rem 0 0;
  padding: 0.5rem 0.7rem;
  color: var(--chalk);
  background: rgba(23, 35, 29, 0.72);
  border: 1px solid rgba(243, 236, 216, 0.25);
  border-radius: var(--radius);
}

.notes-banner {
  padding: 1.15rem 0;
  color: var(--chalk);
  background: var(--board);
  border-top: 1px solid rgba(243, 236, 216, 0.14);
  border-bottom: 1px solid rgba(243, 236, 216, 0.14);
}

.notes-banner-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.notes-banner h2 {
  margin: 0 0 0.25rem;
  font-size: clamp(1.4rem, 3vw, 2rem);
}

.notes-banner p {
  margin: 0;
  color: rgba(243, 236, 216, 0.78);
  font-family: Arial, Helvetica, sans-serif;
}

.notes-banner .eyebrow {
  margin-bottom: 0.35rem;
  color: var(--gold);
}

.caption {
  max-width: 68ch;
  margin: 1.35rem 0 0;
  color: rgba(243, 236, 216, 0.72);
  font-size: 0.88rem;
}

.section {
  padding: clamp(3.5rem, 8vw, 6rem) 0;
}

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

.split {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
  gap: clamp(1.8rem, 6vw, 5rem);
  align-items: start;
}

.copy > *:first-child {
  margin-top: 0;
}

.copy p,
.compact,
.privacy-note {
  max-width: 68ch;
  color: var(--muted);
}

.intro,
.audience {
  background: var(--ivory);
}

.why,
.week {
  background: var(--board);
  color: var(--chalk);
}

.why .eyebrow,
.week .eyebrow {
  color: var(--gold);
}

.why .compact,
.week .copy,
.week p {
  color: rgba(243, 236, 216, 0.78);
}

.text-link {
  display: inline-flex;
  margin-top: 0.65rem;
  color: var(--copper-dark);
  font-family: Arial, Helvetica, sans-serif;
  font-weight: 700;
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.18em;
}

.why .text-link,
.week .text-link {
  color: var(--gold);
}

.comparison {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1rem;
  margin: 2rem 0;
  align-items: stretch;
}

.comparison > div:not(.arrow) {
  padding: 1.25rem;
  background: rgba(243, 236, 216, 0.08);
  border: 1px solid rgba(243, 236, 216, 0.16);
  border-radius: var(--radius);
}

.comparison p {
  margin-bottom: 0;
  color: rgba(243, 236, 216, 0.76);
}

.arrow {
  align-self: center;
  color: var(--gold);
  font-size: 2rem;
}

.protocol-grid,
.audience-grid {
  display: grid;
  gap: 1rem;
  margin: 2rem 0;
}

.protocol-grid {
  grid-template-columns: repeat(6, minmax(0, 1fr));
}

.audience-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.protocol-grid article,
.audience-grid article {
  padding: 1.1rem;
  background: rgba(255, 250, 240, 0.78);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.protocol-grid h3 {
  color: var(--copper-dark);
  font-size: 2.4rem;
}

.pipeline {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.6rem;
  margin: 1rem 0;
}

.pipeline span {
  position: relative;
  min-height: 52px;
  display: grid;
  place-items: center;
  padding: 0.65rem;
  color: var(--chalk);
  background: var(--board-soft);
  border-radius: var(--radius);
  font-family: Arial, Helvetica, sans-serif;
  font-weight: 700;
  text-align: center;
}

.pipeline span:not(:last-child)::after {
  content: "→";
  position: absolute;
  right: -0.5rem;
  color: var(--copper-dark);
  z-index: 1;
}

.examples,
.problems {
  background: var(--paper-deep);
}

.problem-flow {
  display: grid;
  gap: 0.5rem;
  margin: 1rem 0;
}

.problem-flow span {
  position: relative;
  padding: 0.75rem;
  color: var(--chalk);
  background: var(--board-soft);
  border-radius: var(--radius);
  font-family: Arial, Helvetica, sans-serif;
  font-weight: 700;
}

.problem-flow span:not(:last-child)::after {
  content: "↓";
  position: absolute;
  left: 1rem;
  bottom: -0.85rem;
  color: var(--copper-dark);
}

.standout {
  color: var(--copper-dark);
  font-size: 1.2rem;
  font-weight: 700;
}

.timeline {
  display: grid;
  gap: 0.75rem;
  margin: 2rem 0;
  padding: 0;
  list-style: none;
}

.timeline li {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 1rem;
  padding: 1rem;
  background: rgba(255, 250, 240, 0.7);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.timeline strong {
  color: var(--copper-dark);
}

.timeline .is-current {
  background: rgba(201, 155, 79, 0.18);
  border-color: rgba(112, 57, 24, 0.35);
}

.timeline a {
  color: var(--copper-dark);
  font-weight: 700;
}

.timeline em {
  color: var(--muted);
  font-style: italic;
}

.flow {
  padding: 0.75rem;
  color: var(--chalk);
  background: rgba(243, 236, 216, 0.08);
  border-radius: var(--radius);
  font-family: Arial, Helvetica, sans-serif;
  overflow-wrap: anywhere;
}

.schedule {
  display: grid;
  gap: 0.5rem;
  margin: 1rem 0;
}

.schedule div {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 1rem;
  padding: 0.6rem 0;
  border-bottom: 1px solid rgba(243, 236, 216, 0.18);
}

.schedule dt {
  color: var(--gold);
  font-family: Arial, Helvetica, sans-serif;
  font-weight: 700;
}

.schedule dd {
  margin: 0;
}

.plain-list {
  padding-left: 1.2rem;
  color: var(--muted);
}

button:focus-visible,
a:focus-visible {
  outline: 3px solid rgba(201, 155, 79, 0.85);
  outline-offset: 3px;
}

.help,
.optional {
  margin: 0.35rem 0 0;
  color: var(--muted);
  font-family: Arial, Helvetica, sans-serif;
  font-size: 0.88rem;
}

.footer {
  padding: 2rem 0;
  color: rgba(243, 236, 216, 0.78);
  background: #111713;
}

.footer-inner {
  width: min(var(--content), calc(100% - 2rem));
  margin: 0 auto;
  display: grid;
  gap: 1rem;
}

.footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  font-family: Arial, Helvetica, sans-serif;
}

.footer a {
  color: var(--gold);
}

.simple-page {
  min-height: 100vh;
  background: var(--ivory);
}

.privacy-main {
  width: min(760px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 4rem 0;
}

.privacy-card {
  padding: clamp(1.2rem, 5vw, 2rem);
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.privacy-card h1 {
  max-width: none;
  color: var(--ink);
  font-size: clamp(2.3rem, 8vw, 4.5rem);
}

@media (max-width: 860px) {
  .nav {
    align-items: flex-start;
    flex-direction: column;
    padding: 0.7rem 0;
  }

  .nav-links {
    width: 100%;
  }

  .hero {
    min-height: auto;
  }

  .hero-media {
    background-position: 54% center;
  }

  .hero-overlay {
    background:
      linear-gradient(0deg, rgba(13, 18, 15, 0.93), rgba(13, 18, 15, 0.68) 62%, rgba(13, 18, 15, 0.34)),
      linear-gradient(90deg, rgba(13, 18, 15, 0.82), rgba(13, 18, 15, 0.42));
  }

  .hero-content {
    padding-top: 17rem;
  }

  .split {
    grid-template-columns: 1fr;
  }

  .protocol-grid,
  .audience-grid {
    grid-template-columns: 1fr;
  }

  .pipeline {
    grid-template-columns: 1fr;
  }

  .pipeline span:not(:last-child)::after {
    content: "↓";
    right: auto;
    bottom: -0.9rem;
  }

  .comparison {
    grid-template-columns: 1fr;
  }

  .arrow {
    justify-self: center;
  }
}

@media (max-width: 560px) {
  .nav-links a {
    padding: 0.5rem 0.55rem;
    font-size: 0.85rem;
  }

  .hero-content {
    width: min(100% - 1.25rem, 780px);
    padding-top: 13rem;
  }

  .hero-actions .button {
    width: 100%;
  }

  .notes-banner-inner {
    display: grid;
  }

  .notes-banner .button {
    width: 100%;
  }

  .section-inner {
    width: min(100% - 1.25rem, var(--content));
  }

  .timeline li,
  .schedule div {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }
}