/* Article pages linked from airi.html: same cream page and Inter. */

@font-face {
  font-family: "Inter";
  src: url("../fonts/Inter-Regular.woff2") format("woff2");
  font-weight: 400;
  font-style: normal;
  font-display: swap;
}

@font-face {
  font-family: "Inter";
  src: url("../fonts/Inter-Medium.woff2") format("woff2");
  font-weight: 500;
  font-style: normal;
  font-display: swap;
}

:root {
  --cream: #fcf6ef;
  --ink: #161c27;
  --teal: #2fbead;
  --card: #fff;
  --bg: var(--cream);
  --text: var(--ink);
  --muted: #5c564e;
  --border: rgba(22, 28, 39, 0.12);
  --glass: var(--card);
  --surface-card: var(--card);
  --example-border: var(--teal);
  --pre-bg: #161c27;
  --chip-bg: #fff;
  --callout-bg: #fff;
  --link: #1a8f82;
  --code-bg: rgba(22, 28, 39, 0.06);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--cream);
  color: var(--ink);
  font-family: "Inter", system-ui, sans-serif;
  font-size: 1.05rem;
  line-height: 1.6;
  text-wrap: pretty;
}

a { color: inherit; }
code { font-size: 0.92em; background: var(--code-bg); padding: 0.05em 0.3em; border-radius: 0.25rem; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 2;
  background: rgba(252, 246, 239, 0.92);
  border-bottom: 1px solid var(--border);
}

.site-header__inner {
  width: min(72rem, calc(100% - 2rem));
  margin: 0 auto;
  min-height: 3.6rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  font-weight: 500;
  font-size: 1.05rem;
  text-decoration: none;
}

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.9rem;
  font-size: 0.95rem;
}

.nav a { text-decoration: none; }
.nav a:hover,
.nav a[aria-current="page"] { text-decoration: underline; text-underline-offset: 0.2em; }

.article {
  width: min(42rem, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2.5rem 0 4rem;
}

.back-link {
  display: inline-block;
  margin-bottom: 1.25rem;
  text-decoration: none;
}

.back-link:hover { text-decoration: underline; }

.article__title,
.article h1,
.article h2,
.article h3 {
  font-weight: 500;
  letter-spacing: -0.02em;
}

.article__title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  margin: 0 0 0.6rem;
  line-height: 1.2;
}

.skill-id {
  margin: 0 0 0.75rem;
  font-family: ui-monospace, Menlo, Consolas, monospace;
  font-size: 0.85rem;
  color: var(--muted);
}

.article__meta { display: flex; flex-wrap: wrap; gap: 0.5rem; margin: 0 0 1rem; }

.article__lead {
  margin: 0 0 1.5rem;
  font-size: 1.15rem;
}

.article h2 { font-size: 1.35rem; margin: 2rem 0 0.6rem; }
.article h3 { font-size: 1.1rem; margin: 1.4rem 0 0.4rem; }
.article p { margin: 0.6rem 0; }
.article ul, .article ol { padding-left: 1.2rem; }
.article li { margin: 0.35rem 0; }
.article ul { list-style: none; padding-left: 0; }
.article ul li { position: relative; padding-left: 1.35rem; }
.article ul li::before { content: "→"; position: absolute; left: 0; color: #167c70; }

.chip {
  display: inline-flex;
  padding: 0.25rem 0.7rem;
  border-radius: 999px;
  background: var(--card);
  font-size: 0.85rem;
}

.example {
  margin: 1rem 0;
  padding: 1rem 1.1rem;
  background: var(--card);
  border-radius: 10px;
}

.example pre {
  margin: 0.6rem 0 0;
  padding: 0.9rem 1rem;
  overflow-x: auto;
  background: var(--pre-bg);
  color: #fcf6ef;
  border-radius: 8px;
  font-size: 0.88rem;
  line-height: 1.45;
}

.example pre code { background: none; color: inherit; padding: 0; }

.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
  margin: 1.25rem 0 0;
}

.steps li {
  position: relative;
  padding: 0 0 1.25rem 2.6rem;
  margin-left: 0.75rem;
  border-left: 1px solid var(--border);
}

.steps li:last-child { border-left-color: transparent; padding-bottom: 0; }

.steps li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: -0.85rem;
  top: 0;
  width: 1.7rem;
  height: 1.7rem;
  border-radius: 50%;
  background: var(--teal);
  border: 1px solid var(--teal);
  color: #fff;
  font-weight: 600;
  font-size: 0.85rem;
  display: grid;
  place-items: center;
}

.callout {
  margin: 1.5rem 0;
  padding: 1rem 1.15rem;
  background: var(--card);
  border-radius: 10px;
}

.callout p { margin: 0; }

.article__actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 2rem; }

.btn {
  display: inline-flex;
  text-decoration: none;
  background: var(--card);
  border-radius: 10px;
  padding: 0.7rem 1rem;
}

.btn-primary { background: var(--ink); color: #fff; }
.btn:hover { text-decoration: underline; text-underline-offset: 0.15em; }

.graph {
  margin: 1.25rem 0;
  padding: 1rem;
  background: var(--card);
  border-radius: 10px;
  overflow-x: auto;
}

.lesson-toc,
.tree-card {
  background: var(--card);
  border-color: transparent;
}

.site-footer { padding: 0 0 2.5rem; }
.site-footer__inner {
  width: min(42rem, calc(100% - 2rem));
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  font-size: 0.95rem;
}
.site-footer a { text-underline-offset: 0.15em; }

@media (max-width: 720px) {
  .site-header__inner, .site-footer__inner { flex-direction: column; align-items: flex-start; }
  .nav { padding-bottom: 0.6rem; }
}