:root {
  --paper: #fdfdfa;
  --sheet: #ffffff;
  --dot: #c9d1e3;
  --ink: #1b1e2e;
  --muted: #596079;
  --blue: #2d4a9c;
  --blue-dark: #1f3577;
  --mark: #ffe34f;
  --hair: #dfe3ee;
}

* {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background-color: var(--paper);
  background-image: radial-gradient(var(--dot) 1px, transparent 1.2px);
  background-size: 24px 24px;
  color: var(--ink);
  font-family: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 18px;
  line-height: 1.7;
}

a {
  color: var(--blue);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--blue-dark);
  background: var(--mark);
}

.topbar {
  background: var(--ink);
  color: #fff;
}

.topbar-in {
  max-width: 1040px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px 24px;
}

.brand {
  color: #fff;
  font-size: 26px;
  font-weight: 800;
  letter-spacing: -0.01em;
  text-decoration: none;
  line-height: 1.2;
}

.brand span {
  background: var(--mark);
  color: var(--ink);
  padding: 0 8px;
  margin-right: 2px;
}

.brand:hover {
  background: transparent;
  color: #fff;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 22px;
  font-size: 15px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.nav a {
  color: #dfe5f7;
  text-decoration: none;
  padding: 2px 0;
}

.nav a:hover,
.nav a.on {
  background: transparent;
  color: var(--mark);
}

.page {
  max-width: 1040px;
  margin: 28px auto 48px;
  padding: 0 20px;
}

.sheet {
  background: var(--sheet);
  border: 1px solid var(--hair);
  box-shadow: 0 10px 30px rgba(27, 30, 46, 0.07);
  padding: 44px 56px 52px;
}

.kicker {
  margin: 0 0 12px;
  font-size: 14px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
}

.kicker b {
  background: var(--mark);
  color: var(--ink);
  padding: 1px 8px;
  font-weight: 700;
}

h1 {
  margin: 0 0 22px;
  font-size: 44px;
  line-height: 1.12;
  font-weight: 800;
  letter-spacing: -0.02em;
  overflow-wrap: break-word;
}

h2 {
  margin: 40px 0 12px;
  font-size: 27px;
  line-height: 1.25;
  font-weight: 750;
  letter-spacing: -0.01em;
}

h2 span {
  background: linear-gradient(transparent 58%, var(--mark) 58%);
}

.lead {
  font-size: 21px;
  line-height: 1.6;
  color: #2b3045;
  margin: 0 0 8px;
}

.text {
  max-width: 720px;
}

.text p {
  margin: 0 0 16px;
}

.text ul,
.text ol {
  margin: 0 0 18px;
  padding-left: 26px;
}

.text li {
  margin-bottom: 9px;
  padding-left: 4px;
}

.text li::marker {
  color: var(--blue);
  font-weight: 700;
}

.hero {
  display: flex;
  flex-wrap: wrap;
  gap: 24px 48px;
  align-items: flex-end;
  justify-content: space-between;
  padding-bottom: 30px;
  border-bottom: 2px solid var(--ink);
}

.hero h1 {
  margin: 0;
  max-width: 640px;
}

.hero p {
  margin: 0;
  max-width: 340px;
  color: var(--muted);
  font-size: 17px;
}

.toc {
  list-style: none;
  margin: 0;
  padding: 0;
}

.toc li {
  display: grid;
  grid-template-columns: 84px 1fr;
  gap: 4px 24px;
  padding: 26px 0;
  border-bottom: 1px solid var(--hair);
}

.toc .no {
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: 40px;
  font-weight: 700;
  line-height: 1.1;
  color: var(--blue);
}

.toc h3 {
  margin: 0 0 6px;
  font-size: 26px;
  line-height: 1.25;
  font-weight: 750;
  overflow-wrap: break-word;
}

.toc h3 a {
  color: var(--ink);
  text-decoration: none;
}

.toc h3 a:hover {
  background: var(--mark);
}

.toc p {
  margin: 0 0 8px;
  color: #3a4058;
  font-size: 17px;
  line-height: 1.6;
}

.tag {
  display: inline-block;
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  font-size: 13px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.tag b {
  background: var(--mark);
  color: var(--ink);
  padding: 1px 7px;
  margin-right: 8px;
}

.tips {
  margin: 44px 0 0;
}

.tips h2 {
  margin-top: 0;
}

.tips dl {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0 48px;
  margin: 0;
}

.tips dt {
  margin-top: 18px;
  font-weight: 750;
  font-size: 19px;
}

.tips dd {
  margin: 2px 0 0;
  color: #3a4058;
  font-size: 17px;
  line-height: 1.6;
}

.more {
  margin-top: 48px;
  padding-top: 8px;
  border-top: 2px solid var(--ink);
}

.more h2 {
  margin-top: 20px;
  font-size: 22px;
}

.more ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.more li {
  padding: 10px 0;
  border-bottom: 1px solid var(--hair);
  overflow-wrap: break-word;
}

.more li span {
  display: inline-block;
  min-width: 52px;
  font-family: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color: var(--blue);
  font-weight: 700;
}

.note {
  margin-top: 36px;
  padding: 16px 20px;
  background: #fff9d6;
  font-size: 16px;
  line-height: 1.6;
  max-width: 720px;
}

.foot {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 20px 40px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

.foot p {
  margin: 0 0 6px;
}

@media (max-width: 760px) {
  body {
    font-size: 17px;
  }

  .sheet {
    padding: 26px 20px 34px;
  }

  h1 {
    font-size: 32px;
  }

  h2 {
    font-size: 23px;
    margin-top: 32px;
  }

  .lead {
    font-size: 19px;
  }

  .toc li {
    grid-template-columns: 1fr;
  }

  .toc .no {
    font-size: 28px;
  }

  .toc h3 {
    font-size: 22px;
  }

  .tips dl {
    grid-template-columns: 1fr;
  }

  .brand {
    font-size: 22px;
  }

  .page {
    margin-top: 16px;
    padding: 0 12px;
  }
}