:root {
  color-scheme: light;
  --paper: #efe7d7;
  --paper-light: #faf6ec;
  --ink: #15202b;
  --muted: #66707a;
  --line: rgba(21, 32, 43, 0.18);
  --accent: #a93d2d;
  --blue: #315b73;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
body { margin: 0; color: var(--ink); background: var(--paper); line-height: 1.65; }
a { color: inherit; }
.site-header, main, footer { width: min(1180px, calc(100% - 32px)); margin-inline: auto; }
.site-header { min-height: 76px; display: flex; align-items: center; justify-content: space-between; border-bottom: 1px solid var(--line); }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; }
.brand span { display: grid; width: 42px; height: 42px; place-items: center; color: var(--paper-light); background: var(--ink); border-radius: 50%; font-weight: 800; }
.site-header nav { display: flex; gap: 22px; font-size: 0.92rem; }
main { padding-block: 30px 72px; }
.breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 38px; color: var(--muted); font-size: 0.86rem; }
.eyebrow { margin: 0 0 10px; color: var(--accent); font-size: 0.76rem; font-weight: 800; letter-spacing: 0.14em; text-transform: uppercase; }
.hero { display: grid; grid-template-columns: minmax(0, 1.55fr) minmax(270px, 0.7fr); gap: 56px; align-items: end; padding-bottom: 50px; border-bottom: 1px solid var(--line); }
.hero h1 { max-width: 900px; margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: clamp(3rem, 8vw, 7rem); font-weight: 500; line-height: 0.94; letter-spacing: -0.055em; }
.hero > div > p:last-child { max-width: 740px; margin: 28px 0 0; color: var(--muted); font-size: 1.08rem; }
.hero dl { margin: 0; border-top: 1px solid var(--line); }
.hero dl div { display: grid; grid-template-columns: 95px 1fr; gap: 16px; padding: 12px 0; border-bottom: 1px solid var(--line); }
.hero dt { color: var(--muted); font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.08em; }
.hero dd { margin: 0; font-weight: 700; }
.study-note { display: grid; grid-template-columns: 0.55fr 1.45fr; gap: 34px; margin: 38px 0; padding: 22px 26px; color: var(--paper-light); background: var(--ink); }
.language-variants { align-items: center; border-bottom: 1px solid var(--line); display: flex; gap: 22px; justify-content: space-between; padding: 18px 0; }
.language-variants > strong { font: 800 0.7rem/1 ui-monospace, SFMono-Regular, Menlo, monospace; letter-spacing: 0.09em; text-transform: uppercase; }
.language-variants > div { display: flex; flex-wrap: wrap; gap: 8px; justify-content: flex-end; }
.language-variants a { border: 1px solid var(--line); font: 800 0.68rem/1 ui-monospace, SFMono-Regular, Menlo, monospace; padding: 10px 13px; text-decoration: none; text-transform: uppercase; }
.language-variants a:hover, .language-variants a[aria-current="page"] { background: var(--ink); color: var(--paper-light); }
.study-note p { margin: 0; color: rgba(250, 246, 236, 0.76); }
.editorial { display: grid; grid-template-columns: 0.8fr 1.2fr; gap: 56px 72px; margin-block: 64px; }
.editorial header h2, .source-card h2 { margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: clamp(2.2rem, 5vw, 4.4rem); font-weight: 500; line-height: 1; letter-spacing: -0.04em; }
.editorial header > p:last-child { color: var(--muted); }
.editorial > ol { margin: 0; padding: 0; list-style: none; counter-reset: steps; }
.editorial > ol li { counter-increment: steps; display: grid; grid-template-columns: 44px 1fr; gap: 18px; padding: 22px 0; border-top: 1px solid var(--line); }
.editorial > ol li::before { content: counter(steps, decimal-leading-zero); color: var(--accent); font-weight: 800; }
.editorial section { grid-column: 2; padding-top: 28px; border-top: 1px solid var(--line); }
.editorial h3 { margin-top: 0; font-size: 1.15rem; }
.editorial ul { padding-left: 20px; }
.accuracy-note { color: var(--muted); font-size: 0.9rem; }
.source-card { display: grid; grid-template-columns: 1.3fr 0.7fr; gap: 42px; padding: 38px; background: var(--paper-light); border: 1px solid var(--line); }
.source-card h2 { font-size: clamp(2rem, 4vw, 3.2rem); }
.source-actions { display: flex; flex-direction: column; justify-content: center; gap: 12px; }
.source-actions a, .next-actions a { padding: 13px 16px; border: 1px solid var(--line); text-align: center; text-decoration: none; font-weight: 700; }
.source-actions .primary { color: var(--paper-light); background: var(--accent); border-color: var(--accent); }
.code-panel { margin-top: 38px; border: 1px solid var(--line); background: #101721; color: #e8edf2; }
.code-panel-header { align-items: center; display: flex; justify-content: space-between; gap: 22px; padding: 22px 26px; }
.code-panel-header > span:first-child { display: grid; }
.code-panel-header small { color: #9fb0bf; text-transform: uppercase; letter-spacing: 0.1em; }
.code-panel-header strong { color: #f3f6fa; font-size: 1.15rem; }
.language-badge { border: 1px solid #8dd8ff; color: #8dd8ff; font: 800 0.67rem/1 ui-monospace, SFMono-Regular, Menlo, monospace; padding: 8px 10px; text-transform: uppercase; }
.code-warning { padding: 10px 26px; color: #f5dbc5; background: #7c3429; font-size: 0.88rem; }
.code-panel pre { background: linear-gradient(145deg, #050a12 0%, #0a1522 55%, #07101a 100%); border-top: 1px solid rgba(255,255,255,0.12); margin: 0; overflow-x: auto; padding: 22px 0 30px; tab-size: 2; }
.code-panel code { color: #dce6f3; display: block; font: 0.82rem/1.65 "SFMono-Regular", Consolas, monospace; }
.code-line { display: grid; grid-template-columns: 58px minmax(max-content, 1fr); min-height: 1.65em; padding-right: 24px; white-space: pre; }
.code-line:hover { background: rgba(220, 239, 178, 0.055); }
.line-number { border-right: 1px solid #263244; color: #64748b; margin-right: 18px; padding-right: 13px; text-align: right; user-select: none; }
.token-keyword, .token-preprocessor { color: #c586c0; }
.token-string { color: #ce9178; }
.token-number { color: #b5cea8; }
.token-comment { color: #6a9955; font-style: italic; }
.token-type { color: #4ec9b0; }
.token-function { color: #dcdcaa; }
.token-constant { color: #4fc1ff; }
.token-operator { color: #d4d4d4; }
.related-problems { display: grid; grid-template-columns: 0.65fr 1.35fr; gap: 42px; margin-top: 56px; padding-top: 38px; border-top: 1px solid var(--line); }
.related-problems h2 { margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: clamp(2rem, 4vw, 3.2rem); font-weight: 500; line-height: 1; letter-spacing: -0.04em; }
.related-problem-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
.related-problem-grid a { display: grid; align-content: space-between; gap: 24px; min-height: 130px; padding: 18px; border: 1px solid var(--line); text-decoration: none; }
.related-problem-grid a:hover, .related-problem-grid a:focus-visible { border-color: var(--accent); background: var(--paper-light); }
.related-problem-grid strong { line-height: 1.3; }
.related-problem-grid span { color: var(--muted); font: 700 0.68rem/1.4 ui-monospace, SFMono-Regular, Menlo, monospace; letter-spacing: 0.04em; text-transform: uppercase; }
.next-actions { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; margin-top: 38px; }
footer { display: flex; justify-content: space-between; gap: 20px; padding-block: 30px; border-top: 1px solid var(--line); color: var(--muted); font-size: 0.9rem; }

@media (max-width: 760px) {
  .site-header nav { display: none; }
  .hero, .editorial, .source-card, .study-note, .related-problems { grid-template-columns: 1fr; gap: 28px; }
  .hero h1 { font-size: clamp(2.8rem, 15vw, 5.2rem); }
  .editorial section { grid-column: 1; }
  .next-actions { grid-template-columns: 1fr; }
  .related-problem-grid { grid-template-columns: 1fr; }
  .code-panel-header { align-items: flex-start; padding: 19px 18px; }
  .code-panel pre { background: linear-gradient(145deg, #050a12 0%, #0a1522 55%, #07101a 100%); }
  .code-line { grid-template-columns: 48px minmax(max-content, 1fr); padding-right: 16px; }
  footer { flex-direction: column; }
  .language-variants { align-items: flex-start; flex-direction: column; }
  .language-variants > div { justify-content: flex-start; }
}