:root {
  color-scheme: light;
  --bg: #f6f5f2;
  --text: #1c1b19;
  --muted: #5e5a54;
  --card: #fffcf8;
  --border: #e3dfd6;
  --accent: #0b4f9e;
  --accent-soft: #e7f0fa;
  --code-bg: #efece5;
  --code-text: #1a1917;
  --callout: #f4efe2;
  --callout-border: #c4a35a;
  --shadow: 0 1px 2px rgb(28 27 25 / 6%);
  --max: 46rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --bg: #141618;
    --text: #eceae6;
    --muted: #b4b0a8;
    --card: #1c1f23;
    --border: #34383e;
    --accent: #9ec4f5;
    --accent-soft: #1d2c3d;
    --code-bg: #101214;
    --code-text: #eceae6;
    --callout: #2a261c;
    --callout-border: #c4a35a;
    --shadow: 0 1px 2px rgb(0 0 0 / 35%);
  }
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", system-ui, sans-serif;
  font-size: 1.0625rem;
  line-height: 1.75;
}

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

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

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

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

header.page {
  padding: 2.5rem 0 1.25rem;
  border-bottom: 1px solid var(--border);
}

h1 {
  margin: 0 0 0.6rem;
  font-size: clamp(1.55rem, 2.4vw, 2rem);
  line-height: 1.35;
  letter-spacing: 0.01em;
}

.purpose {
  margin: 0 0 1rem;
  font-size: 1.05rem;
}

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

nav.toc {
  margin-top: 1.4rem;
  padding: 0.9rem 1rem 1rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.toc-label {
  margin: 0 0 0.35rem;
  font-weight: 700;
}

nav.toc ol {
  margin: 0;
  padding-left: 1.3rem;
}

nav.toc a {
  text-decoration: none;
}

nav.toc a:hover {
  text-decoration: underline;
}

main {
  padding-bottom: 2.5rem;
}

section {
  padding-top: 0.4rem;
  margin-top: 2rem;
}

h2 {
  margin: 0 0 0.8rem;
  padding-top: 0.4rem;
  font-size: 1.4rem;
  line-height: 1.4;
}

h3 {
  margin: 1.5rem 0 0.5rem;
  font-size: 1.12rem;
  line-height: 1.45;
}

p {
  margin: 0.7rem 0;
}

ul,
ol {
  margin: 0.6rem 0 0.9rem;
  padding-left: 1.35rem;
}

li + li {
  margin-top: 0.35rem;
}

code,
pre {
  font-family: ui-monospace, "SFMono-Regular", "Cascadia Code", Menlo, Consolas, monospace;
  font-size: 0.88em;
}

code {
  padding: 0.08em 0.35em;
  background: var(--code-bg);
  color: var(--code-text);
  border-radius: 4px;
}

pre {
  margin: 0.9rem 0 1.1rem;
  padding: 0.95rem 1rem;
  overflow-x: auto;
  background: var(--code-bg);
  color: var(--code-text);
  border: 1px solid var(--border);
  border-radius: 10px;
  line-height: 1.55;
}

pre code {
  padding: 0;
  background: transparent;
  border-radius: 0;
  font-size: 0.86rem;
}

.table-scroll {
  margin: 0.9rem 0 1.15rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card);
}

table {
  width: 100%;
  min-width: 36rem;
  border-collapse: collapse;
}

th,
td {
  padding: 0.55rem 0.75rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--border);
}

th {
  background: var(--accent-soft);
  font-weight: 700;
  white-space: nowrap;
}

tr:last-child td {
  border-bottom: 0;
}

.callout {
  margin: 1rem 0;
  padding: 0.85rem 1rem;
  background: var(--callout);
  border-left: 4px solid var(--callout-border);
  border-radius: 0 10px 10px 0;
}

.callout p {
  margin: 0;
}

.flow {
  list-style: none;
  margin: 1rem 0 1.2rem;
  padding: 0;
}

.flow li {
  position: relative;
  margin: 0;
  padding: 0.8rem 1rem;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.flow li + li {
  margin-top: 1.35rem;
}

.flow li + li::before {
  content: "↓";
  position: absolute;
  top: -1.2rem;
  left: 1.15rem;
  color: var(--muted);
  line-height: 1;
}

.flow strong {
  display: block;
}

.flow span {
  display: block;
  color: var(--muted);
  font-size: 0.98rem;
}

.sources {
  margin-top: 0.4rem;
  padding-left: 1.2rem;
  font-size: 0.98rem;
}

footer {
  padding: 1.2rem 0 2.4rem;
  border-top: 1px solid var(--border);
}

@media (max-width: 640px) {
  body {
    font-size: 1rem;
  }

  .wrap {
    width: min(100% - 1.4rem, var(--max));
  }

  header.page {
    padding-top: 1.6rem;
  }

  th,
  td {
    padding: 0.5rem 0.6rem;
  }
}