:root {
  --paper: #f4f5f3;
  --ink: #191d1c;
  --soft: #5d6664;
  --line: #d6dad6;
  --teal: #12564f;
  --sand: #e8e3d8;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #101413;
    --ink: #e6eae8;
    --soft: #8e9a97;
    --line: #232a28;
    --teal: #5fc4b3;
    --sand: #1b201e;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Avenir Next, Segoe UI, Helvetica Neue, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

.shell {
  max-width: 60rem;
  margin: 0 auto;
  padding: 0 1.6rem;
}

header.top {
  border-bottom: 3px double var(--line);
}

header.top .shell {
  padding-top: 1.6rem;
  padding-bottom: 1.6rem;
  display: flex;
  align-items: center;
  gap: 1rem 2rem;
  flex-wrap: wrap;
}

.mark {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink);
  text-decoration: none;
}

.mark em {
  font-style: normal;
  color: var(--teal);
}

header.top .shell nav {
  margin-left: auto;
  font-size: 0.82rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

header.top .shell nav a {
  color: var(--soft);
  text-decoration: none;
  margin-left: 1.5rem;
}

header.top .shell nav a:hover,
header.top .shell nav a:focus {
  color: var(--teal);
}

.hero {
  padding: 4rem 0 3rem;
  border-bottom: 1px solid var(--line);
}

h1 {
  font-size: clamp(2rem, 6vw, 3.1rem);
  line-height: 1.06;
  letter-spacing: -0.03em;
  margin: 0 0 1rem;
  max-width: 16ch;
  font-weight: 700;
}

.hero p {
  max-width: 44ch;
  font-size: 1.12rem;
  color: var(--soft);
  margin: 0;
}

h2 {
  font-size: 0.8rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--soft);
  font-weight: 700;
  margin: 3.4rem 0 1.4rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--line);
}

h3 {
  font-size: 1.08rem;
  margin: 0 0 0.4rem;
  letter-spacing: -0.01em;
}

p { margin: 0 0 1.1rem; max-width: 62ch; }

a { color: var(--teal); }

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr));
  gap: 1.6rem;
}

.card {
  border: 1px solid var(--line);
  padding: 1.3rem;
  background: var(--sand);
}

.card .tag {
  font-size: 0.7rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--teal);
  display: block;
  margin-bottom: 0.6rem;
}

.card p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--soft);
}

dl.spec {
  display: grid;
  grid-template-columns: 11rem 1fr;
  gap: 0.55rem 1.4rem;
  margin: 0 0 1.6rem;
  font-size: 0.94rem;
}

dl.spec dt {
  color: var(--soft);
  font-size: 0.74rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  padding-top: 0.2rem;
}

dl.spec dd { margin: 0; }

ol.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
  margin: 0;
}

ol.steps li {
  counter-increment: step;
  border-top: 1px solid var(--line);
  padding: 1.3rem 0 1.3rem 3.4rem;
  position: relative;
  max-width: 62ch;
}

ol.steps li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 1.35rem;
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  color: var(--teal);
  font-weight: 700;
}

footer.bottom {
  margin-top: 4.5rem;
  border-top: 3px double var(--line);
  font-size: 0.85rem;
  color: var(--soft);
}

footer.bottom .shell {
  padding-top: 1.6rem;
  padding-bottom: 3rem;
  display: flex;
  gap: 0.6rem 2rem;
  flex-wrap: wrap;
}

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

.big404 {
  font-size: clamp(4rem, 18vw, 9rem);
  letter-spacing: -0.05em;
  line-height: 1;
  color: var(--line);
  margin: 3rem 0 0.5rem;
  font-weight: 700;
}

@media (max-width: 34rem) {
  header.top .shell nav { margin-left: 0; width: 100%; }
  header.top .shell nav a { margin: 0 1.4rem 0 0; }
  dl.spec { grid-template-columns: 1fr; gap: 0.15rem; }
  dl.spec dd { margin-bottom: 0.7rem; }
}