:root {
  color-scheme: light;
  --ink: #1c1917;
  --muted: #57534e;
  --line: #e7e5e4;
  --paper: #fafaf9;
  --accent: #9a3412;
  --card: #ffffff;
}

* { box-sizing: border-box; }

body {
  margin: 0 auto;
  max-width: 44rem;
  padding: 2.5rem 1.25rem 4rem;
  font-family: "Segoe UI", "Apple SD Gothic Neo", "Malgun Gothic", sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.65;
  font-size: 1.05rem;
}

.skip {
  position: absolute;
  left: 0.75rem;
  top: -4rem;
  background: var(--card);
  color: var(--ink);
  padding: 0.4rem 0.7rem;
  border: 1px solid var(--line);
}

.skip:focus { top: 0.75rem; }

a {
  color: var(--accent);
  text-underline-offset: 0.15em;
}

a:hover { text-decoration-thickness: 2px; }

header { margin-bottom: 1.5rem; }

.mark {
  margin: 0 0 0.45rem;
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.82rem;
  font-weight: 650;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
}

h1 {
  margin: 0;
  font-size: clamp(1.85rem, 4vw, 2.45rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
}

header > p {
  margin: 0.8rem 0 0;
  color: var(--muted);
}

.facts,
.toc {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1rem;
  margin: 1rem 0 0;
  padding: 0;
  list-style: none;
}

.facts { color: var(--muted); font-size: 0.95rem; }

.toc { font-size: 0.95rem; }

.note {
  margin: 0 0 0.5rem;
  padding: 0.15rem 0 0.15rem 0.9rem;
  border-left: 3px solid var(--accent);
  color: var(--muted);
}

section { margin-top: 2.25rem; scroll-margin-top: 1rem; }

h2 {
  margin: 0 0 0.65rem;
  font-size: 1.35rem;
  line-height: 1.3;
}

h3 {
  margin: 1.4rem 0 0.4rem;
  font-size: 1.08rem;
}

p, li, dd { color: var(--ink); }

ul, ol { padding-left: 1.25rem; }

li + li { margin-top: 0.25rem; }

code, pre {
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.88rem;
}

code {
  background: var(--card);
  border: 1px solid var(--line);
  padding: 0.08rem 0.32rem;
  border-radius: 0.2rem;
}

pre {
  background: #1c1917;
  color: #fafaf9;
  padding: 0.95rem 1rem;
  overflow-x: auto;
  line-height: 1.55;
  border-radius: 0.35rem;
}

pre code {
  background: none;
  border: 0;
  padding: 0;
  color: inherit;
  border-radius: 0;
}

.table-wrap { overflow-x: auto; }

table {
  width: 100%;
  min-width: 28rem;
  border-collapse: collapse;
  font-size: 0.98rem;
}

th, td {
  text-align: left;
  padding: 0.55rem 0.45rem;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

th {
  color: var(--muted);
  font-weight: 600;
}

.flow ol {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

.flow li {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 0.35rem;
  padding: 0.85rem 0.9rem 0.95rem;
  counter-increment: step;
}

.flow li::before {
  content: counter(step);
  display: block;
  margin-bottom: 0.35rem;
  color: var(--accent);
  font-family: ui-monospace, Consolas, monospace;
  font-size: 0.82rem;
}

.flow strong { display: block; }

.flow span {
  display: block;
  margin-top: 0.2rem;
  color: var(--muted);
  font-size: 0.92rem;
}

figcaption {
  margin-top: 0.7rem;
  color: var(--muted);
  font-size: 0.95rem;
}

dl { margin: 0; }

dt {
  margin-top: 0.85rem;
  font-weight: 650;
}

dd { margin: 0.15rem 0 0; }

fieldset {
  margin: 0 0 0.9rem;
  padding: 0.7rem 0.9rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: 0.35rem;
  background: var(--card);
}

legend { padding: 0 0.25rem; }

fieldset label {
  display: flex;
  gap: 0.5rem;
  align-items: flex-start;
  margin-top: 0.4rem;
}

button {
  font: inherit;
  color: var(--paper);
  background: var(--ink);
  border: 0;
  border-radius: 0.3rem;
  padding: 0.55rem 0.95rem;
  cursor: pointer;
}

button:hover { background: #44403c; }

#quiz-result {
  min-height: 1.4em;
  margin: 0.8rem 0 0;
  font-weight: 650;
}

details {
  margin-top: 1rem;
  border-top: 1px solid var(--line);
  padding-top: 0.8rem;
}

summary { cursor: pointer; }

footer {
  margin-top: 3rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
}

footer > p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

a:focus-visible,
button:focus-visible,
summary:focus-visible,
input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (max-width: 640px) {
  body { padding-top: 1.5rem; }

  .flow ol { grid-template-columns: 1fr; }

  table { min-width: 22rem; }
}

@media print {
  body {
    max-width: none;
    background: #fff;
    color: #000;
  }

  .skip, nav, button { display: none; }

  pre {
    background: #fff;
    color: #000;
    border: 1px solid #ccc;
  }

  a { color: #000; }
}