:root {
  --bg: #f7f7f4;
  --surface: #ffffff;
  --text: #171717;
  --muted: #666b73;
  --line: #dedfd9;
  --accent: #2457d6;
  --accent-soft: #edf2ff;
  --code: #183153;
  --max: 760px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; }

a:focus-visible {
  outline: 3px solid var(--accent-soft);
  outline-offset: 4px;
  border-radius: 3px;
}

.mobile-nav summary:focus-visible {
  outline: 3px solid var(--accent-soft);
  outline-offset: 4px;
}

.wrap {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.mono {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

header {
  border-bottom: 1px solid var(--line);
  background: rgba(247, 247, 244, .94);
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(10px);
}

header a {
  text-decoration: none;
}

.nav {
  min-height: 66px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  color: var(--text);
  text-decoration: none;
  font-weight: 750;
  font-size: 1.22rem;
  letter-spacing: -.02em;
  display: flex;
  align-items: center;
  gap: 8px;
}

.brand-logo {
  display: block;
  width: 32px;
  height: auto;
}

.back {
  color: var(--muted);
  text-decoration: none;
  font-size: .9rem;
}

.back:hover { color: var(--text); }

.nav-links {
  display: flex;
  gap: 22px;
  color: var(--muted);
  font-size: .92rem;
}

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

.nav-links a:hover {
  color: var(--text);
}

.mobile-nav {
  display: none;
  position: relative;
}

.mobile-nav summary {
  width: 42px;
  height: 40px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  cursor: pointer;
  list-style: none;
}

.mobile-nav summary::-webkit-details-marker { display: none; }

.menu-icon {
  width: 20px;
  display: grid;
  gap: 4px;
}

.menu-icon span {
  display: block;
  height: 2px;
  border-radius: 999px;
  background: var(--text);
}

.mobile-nav-menu {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: min(250px, calc(100vw - 40px));
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 9px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  box-shadow: 0 16px 40px rgba(24, 49, 83, .14);
}

.mobile-nav-menu a {
  padding: 10px 12px;
  border-radius: 8px;
  color: var(--muted);
  font-size: .9rem;
  font-weight: 600;
  text-decoration: none;
}

.mobile-nav-menu a:hover {
  background: var(--accent-soft);
  color: var(--accent);
}

header .wrap {
  width: min(980px, calc(100% - 40px));
}

article { padding: 40px 0 90px; }

article.wrap,
footer .wrap {
  width: min(980px, calc(100% - 40px));
}

article > .kicker,
article > h1,
article > .dek,
article > .meta,
article > .series-banner,
article > .body,
article > .series-nav {
  max-width: 760px;
}

.kicker {
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .08em;
  font: 650 .85rem/1.4 "SFMono-Regular", Consolas, monospace;
}

h1, h2 {
  font-family: "Avenir Next", Avenir, "Helvetica Neue", Helvetica, Arial, sans-serif;
  letter-spacing: -.01em;
  font-weight: 650;
}

h1 {
  margin: 18px 0 22px;
  font-size: clamp(2.45rem, 7vw, 4.5rem);
  line-height: 1.04;
}

h1 .part-title {
  display: block;
  margin-top: 12px;
  color: var(--accent);
  font-size: .45em;
  line-height: 1.25;
  letter-spacing: 0;
}

h2 {
  margin: 56px 0 14px;
  font-size: clamp(1.55rem, 4vw, 2.1rem);
  line-height: 1.25;
}

.dek {
  margin: 0;
  color: var(--muted);
  font-size: 1.2rem;
  line-height: 1.65;
}

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  margin: 30px 0 0;
  padding: 18px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  color: var(--muted);
  font: .8rem/1.4 "SFMono-Regular", Consolas, monospace;
  text-transform: uppercase;
  letter-spacing: .04em;
}

.tag {
  padding: 4px 8px;
  background: var(--accent-soft);
  border-radius: 999px;
  color: var(--accent);
  font-weight: 700;
}

.series-banner {
  margin: 28px 0 0;
  padding: 16px 18px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent);
  border-radius: 10px;
  color: var(--muted);
}

.series-banner strong { color: var(--text); }

.series-banner a {
  color: var(--accent);
  font-weight: 650;
}

.body { margin-top: 48px; }

.body p { margin: 0 0 24px; }

.body strong { font-weight: 700; }

.example {
  margin: 28px 0;
  padding: 20px 24px;
  background: var(--surface);
  border-left: 3px solid var(--accent);
  color: var(--code);
  font-size: 1.08rem;
}

.wide-figure {
  width: 100%;
  margin: 38px 0 44px;
}

.wide-figure img {
  display: block;
  width: 100%;
  height: auto;
  background: white;
  border: 1px solid var(--line);
  border-radius: 14px;
}

.wide-figure figcaption {
  margin-top: 10px;
  color: var(--muted);
  font-size: .82rem;
  text-align: center;
}

.probabilities {
  margin: 26px 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}

.probabilities li {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}

.flow {
  margin: 32px 0;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  color: var(--code);
  font: 650 .9rem/1.8 "SFMono-Regular", Consolas, monospace;
  text-align: center;
}

.closing {
  margin-top: 58px;
  padding: 24px 0;
  border-top: 2px solid var(--text);
  border-bottom: 1px solid var(--line);
  color: var(--text);
}

.closing p { margin: 0; }

.series-nav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 42px;
}

.series-link {
  display: block;
  padding: 18px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  text-decoration: none;
}

.series-link.next { text-align: right; }

.series-link small {
  display: block;
  color: var(--accent);
  font: 650 .72rem/1.4 "SFMono-Regular", Consolas, monospace;
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 4px;
}

.series-link:hover { border-color: var(--accent); }

.series-spacer { min-height: 1px; }

footer {
  border-top: 1px solid var(--line);
  padding: 28px 0 42px;
  color: var(--muted);
  font-size: .9rem;
}

.blog-index {
  padding: 40px 0 0;
}

.blog-index-wrap {
  width: min(980px, calc(100% - 40px));
  margin: 0 auto;
}

.blog-index h1 {
  max-width: 800px;
}

.category-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 30px 0 0;
}

.category-nav a {
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--muted);
  text-decoration: none;
  font-size: .85rem;
}

.category-nav a:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.blog-category {
  padding: 58px 0;
  border-top: 1px solid var(--line);
}

.blog-category:first-of-type {
  margin-top: 58px;
}

.blog-category h2 {
  margin-top: 0;
}

.blog-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.blog-card {
  display: flex;
  flex-direction: column;
  min-height: 250px;
  padding: 24px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  text-decoration: none;
}

.blog-card:hover { border-color: var(--accent); }

.blog-card-meta {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  color: var(--muted);
  font: .75rem/1.4 "SFMono-Regular", Consolas, monospace;
  text-transform: uppercase;
  letter-spacing: .04em;
}

.blog-card h3 {
  margin: 28px 0 12px;
  font-family: "Avenir Next", Avenir, "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 1.35rem;
  line-height: 1.25;
}

.blog-card p {
  margin: 0;
  color: var(--muted);
}

.blog-card .read-more {
  margin-top: auto;
  padding-top: 20px;
  color: var(--accent);
  font-weight: 650;
}

.empty-category {
  margin: 0;
  padding: 24px;
  background: var(--surface);
  border: 1px dashed var(--line);
  border-radius: 12px;
  color: var(--muted);
}

.blog-contact {
  padding: 76px 0;
  border-top: 1px solid var(--line);
}

.contact-panel {
  display: grid;
  grid-template-columns: 1fr .8fr;
  gap: 22px;
  align-items: stretch;
}

.contact-panel > div:first-child,
.contact-links {
  padding: clamp(26px, 4vw, 38px);
  border-radius: 16px;
}

.contact-panel > div:first-child {
  background: var(--surface);
  border: 1px solid var(--line);
}

.eyebrow {
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .09em;
  font: 650 .98rem/1.3 "SFMono-Regular", Consolas, monospace;
  margin-bottom: 20px;
}

.contact-panel h2 {
  margin: 0;
  font-size: clamp(1.65rem, 3vw, 2.25rem);
  line-height: 1.15;
}

.contact-panel p {
  margin: 16px 0 0;
  color: var(--muted);
  max-width: 620px;
}

.contact-links {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  justify-content: center;
  gap: 12px;
  background: var(--accent-soft);
}

.contact-links h3 {
  margin: 0 0 8px;
  font-family: "Avenir Next", Avenir, "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 1.35rem;
  line-height: 1.25;
}

.contact-link {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  color: var(--accent);
  border-bottom: 1px solid rgba(36, 87, 214, .3);
  padding-bottom: 3px;
  font-weight: 650;
  text-decoration: none;
}

.contact-link:hover {
  border-color: var(--accent);
}

.contact-icon {
  width: 18px;
  height: 18px;
  flex: 0 0 18px;
  color: currentColor;
}

.footer-row {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

@media (max-width: 760px) {
  .nav {
    min-height: 62px;
    padding: 10px 0;
  }

  .nav-links {
    display: none;
  }

  .mobile-nav {
    display: block;
  }

  .contact-panel {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 600px) {
  article { padding: 30px 0 68px; }
  .nav { min-height: 58px; }
  .wide-figure { margin-top: 30px; margin-bottom: 36px; }
  .series-nav { grid-template-columns: 1fr; }
  .series-link.next { text-align: left; }
  .series-spacer { display: none; }
  .blog-index { padding: 30px 0 0; }
  .blog-contact { padding: 58px 0; }
  .blog-grid { grid-template-columns: 1fr; }
}