/* ==========================================================================
   reactguide.org — stylesheet
   No external fonts, no CDNs, no trackers. Everything is served from here.
   ========================================================================== */

/* --- Tokens --------------------------------------------------------------- */

:root {
  --brand:        #087ea4;
  --brand-bright: #149eca;
  --accent:       #58c4dc;
  --accent-soft:  #e6f4f9;

  --surface: #ffffff;
  --paper:   #f4f8fa;
  --line:    #dde7ec;
  --ink:     #16181d;
  --text:    #3f4650;
  --muted:   #6b7480;

  --code-bg:    #16191f;
  --code-text:  #d8dee9;
  --code-line:  #262c35;

  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

  --radius: 10px;
  --wrap: 1140px;
  --shadow: 0 1px 2px rgba(22, 24, 29, .06), 0 8px 24px -12px rgba(22, 24, 29, .18);
}

:root[data-theme="dark"] {
  --brand:        #58c4dc;
  --brand-bright: #7ad4e8;
  --accent:       #58c4dc;
  --accent-soft:  #1d2b33;

  --surface: #16181d;
  --paper:   #1b1e25;
  --line:    #2b313b;
  --ink:     #f2f5f8;
  --text:    #c3cbd6;
  --muted:   #8b95a3;

  --code-bg:   #10131a;
  --code-line: #232932;
  --shadow: 0 1px 2px rgba(0, 0, 0, .4), 0 8px 24px -12px rgba(0, 0, 0, .6);
}

/* --- Base ----------------------------------------------------------------- */

*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 88px; }

body {
  margin: 0;
  background: var(--surface);
  color: var(--text);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  color: var(--ink);
  font-weight: 700;
  letter-spacing: -0.022em;
  line-height: 1.22;
  margin: 0;
}

a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

:focus-visible {
  outline: 3px solid var(--brand-bright);
  outline-offset: 2px;
  border-radius: 3px;
}

img { max-width: 100%; }

.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: 24px;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -60px;
  z-index: 100;
  background: var(--brand);
  color: #fff;
  padding: 10px 16px;
  border-radius: 0 0 var(--radius) var(--radius);
  transition: top .15s ease;
}
.skip-link:focus { top: 0; }

/* --- Header --------------------------------------------------------------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: var(--surface);
  background: color-mix(in srgb, var(--surface) 88%, transparent);
  backdrop-filter: saturate(160%) blur(10px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  gap: 20px;
  height: 64px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
  letter-spacing: -0.03em;
  font-size: 18px;
  margin-right: auto;
}
.brand:hover { text-decoration: none; color: var(--brand); }
.brand svg { flex: none; }
.brand .dot { color: var(--brand-bright); }

.brand-mark { animation: orbit 24s linear infinite; transform-origin: 50% 50%; }
@keyframes orbit { to { transform: rotate(360deg); } }

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.site-nav a {
  display: block;
  padding: 7px 12px;
  border-radius: 8px;
  color: var(--text);
  font-size: 15px;
  font-weight: 500;
}
.site-nav a:hover { background: var(--paper); color: var(--ink); text-decoration: none; }
.site-nav a[aria-current] { color: var(--brand); background: var(--accent-soft); }

.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: transparent;
  color: var(--text);
  cursor: pointer;
}
.icon-btn:hover { background: var(--paper); color: var(--ink); }

.nav-toggle { display: none; }
:root[data-theme="dark"] .icon-sun { display: none; }
:root:not([data-theme="dark"]) .icon-moon { display: none; }

/* --- Footer --------------------------------------------------------------- */

.site-footer {
  margin-top: 80px;
  border-top: 1px solid var(--line);
  background: var(--paper);
  font-size: 15px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr;
  gap: 40px;
  padding: 48px 0 32px;
}
.footer-grid h2 {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: .09em;
  color: var(--muted);
  margin-bottom: 14px;
  font-weight: 600;
}
.footer-grid ul { list-style: none; margin: 0; padding: 0; }
.footer-grid li { margin-bottom: 8px; }
.footer-grid p { margin: 0 0 12px; color: var(--muted); max-width: 42ch; }
.footer-bottom {
  border-top: 1px solid var(--line);
  padding: 20px 0 36px;
  color: var(--muted);
  font-size: 13.5px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px 16px;
}

/* --- Home: hero ----------------------------------------------------------- */

.hero { padding: 72px 0 24px; }
.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: center;
}
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: .04em;
  color: var(--brand);
  background: var(--accent-soft);
  padding: 5px 11px;
  border-radius: 999px;
  margin-bottom: 22px;
}
.hero h1 {
  font-size: clamp(34px, 5.2vw, 54px);
  letter-spacing: -0.035em;
  margin-bottom: 20px;
}
.hero h1 em {
  font-style: normal;
  color: var(--brand);
  box-shadow: inset 0 -0.14em 0 var(--accent);
}
.hero p.lede { font-size: 19px; max-width: 46ch; margin: 0 0 30px; }

.cta-row { display: flex; flex-wrap: wrap; gap: 12px; }
.btn {
  display: inline-block;
  padding: 12px 22px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 16px;
  border: 1px solid transparent;
}
.btn:hover { text-decoration: none; }
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-bright); }
:root[data-theme="dark"] .btn-primary { color: #0d1117; }
.btn-ghost { border-color: var(--line); color: var(--ink); background: var(--surface); }
.btn-ghost:hover { border-color: var(--brand); color: var(--brand); }

/* Signature element: the JSX-to-UI panel */
.demo {
  display: grid;
  grid-template-columns: 1fr;
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
  box-shadow: var(--shadow);
  background: var(--surface);
}
.demo-label {
  font-family: var(--mono);
  font-size: 11.5px;
  letter-spacing: .11em;
  text-transform: uppercase;
  padding: 10px 16px;
  color: var(--muted);
  border-bottom: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
}
.demo-code {
  background: var(--code-bg);
  color: var(--code-text);
  font-family: var(--mono);
  font-size: 13.5px;
  line-height: 1.75;
  padding: 16px 18px;
  margin: 0;
  overflow-x: auto;
}
.demo-code .demo-label { border-bottom: none; padding: 0 0 8px; color: #8b95a3; }
.demo-code code { display: block; }
.demo-line { display: block; opacity: 0; transform: translateY(4px); }
.demo-out .demo-label { border-bottom: none; padding: 0 0 10px; }
.demo-out {
  padding: 22px 18px;
  background: var(--paper);
  border-top: 1px solid var(--line);
}
.demo-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
}
.demo-card h3 { font-size: 17px; margin-bottom: 4px; }
.demo-card p { margin: 0; color: var(--muted); font-size: 14.5px; }
.demo-piece { opacity: 0; }
.demo-count {
  margin-top: 12px;
  display: inline-flex;
  align-items: center;
  gap: 10px;
}
.demo-count button {
  font: inherit;
  font-size: 14px;
  padding: 5px 12px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
}
.demo-count button:hover { border-color: var(--brand); color: var(--brand); }
.demo-count strong { font-variant-numeric: tabular-nums; color: var(--brand); }

.demo-line,
.demo-piece {
  animation: rise .38s cubic-bezier(.2, .7, .3, 1) forwards;
  animation-delay: calc(var(--i) * 90ms);
}
@keyframes rise { to { opacity: 1; transform: none; } }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .brand-mark { animation: none; }
  .demo-line,
  .demo-piece { animation: none; opacity: 1; transform: none; }
}

/* --- Home: chapter grid --------------------------------------------------- */

.section { padding: 64px 0 0; }
.section-head { margin-bottom: 32px; max-width: 60ch; }
.section-head h2 { font-size: clamp(26px, 3.4vw, 34px); margin-bottom: 10px; }
.section-head p { margin: 0; color: var(--muted); }

.chapters {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(290px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
}
.chapter-card {
  background: var(--surface);
  padding: 22px 24px 24px;
  display: block;
  color: inherit;
  transition: background .15s ease;
}
.chapter-card:hover { background: var(--paper); text-decoration: none; }
.chapter-card:hover h3 { color: var(--brand); }
.chapter-card .num {
  font-family: var(--mono);
  font-size: 12.5px;
  color: var(--brand);
  letter-spacing: .06em;
}
.chapter-card h3 { font-size: 17.5px; margin: 6px 0 6px; }
.chapter-card p { margin: 0; font-size: 14.5px; color: var(--muted); line-height: 1.6; }

.callout-strip {
  margin-top: 56px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--brand);
  border-radius: var(--radius);
  background: var(--paper);
  padding: 22px 26px;
}
.callout-strip h2 { font-size: 19px; margin-bottom: 8px; }
.callout-strip p { margin: 0; color: var(--muted); max-width: 72ch; }

/* --- Guide layout --------------------------------------------------------- */

.guide-layout {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 56px;
  padding-top: 40px;
  align-items: start;
}

.toc {
  position: sticky;
  top: 88px;
  max-height: calc(100vh - 110px);
  overflow-y: auto;
  padding-right: 8px;
  font-size: 14.5px;
}
.toc h2 {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--muted);
  margin-bottom: 12px;
  font-weight: 600;
}
.toc ol { list-style: none; margin: 0; padding: 0; counter-reset: ch; }
.toc li { counter-increment: ch; }
.toc a {
  display: flex;
  gap: 10px;
  padding: 6px 10px;
  border-radius: 7px;
  color: var(--text);
  border-left: 2px solid transparent;
}
.toc a::before {
  content: counter(ch, decimal-leading-zero);
  font-family: var(--mono);
  font-size: 12px;
  color: var(--muted);
  padding-top: 2px;
}
.toc a:hover { background: var(--paper); color: var(--ink); text-decoration: none; }
.toc a[aria-current] {
  color: var(--brand);
  background: var(--accent-soft);
  font-weight: 600;
}
.toc a[aria-current]::before { color: var(--brand); }

.toc-mobile { display: none; }

/* --- Article -------------------------------------------------------------- */

.article { max-width: 760px; }
.article-head { border-bottom: 1px solid var(--line); padding-bottom: 26px; margin-bottom: 8px; }
.article-head .num {
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--brand);
  text-transform: uppercase;
}
.article-head h1 {
  font-size: clamp(30px, 4.4vw, 42px);
  letter-spacing: -0.034em;
  margin: 8px 0 14px;
}
.article-head .lede { font-size: 18.5px; color: var(--muted); margin: 0; max-width: 54ch; }

.article h2 {
  font-size: 25px;
  margin: 44px 0 14px;
  padding-top: 4px;
}
.article h3 { font-size: 19px; margin: 30px 0 10px; }
.article p { margin: 0 0 18px; }
.article ul, .article ol { margin: 0 0 20px; padding-left: 22px; }
.article li { margin-bottom: 8px; }
.article strong { color: var(--ink); font-weight: 600; }

.article :not(pre) > code,
.article li code,
.article p code {
  font-family: var(--mono);
  font-size: .875em;
  background: var(--accent-soft);
  color: var(--brand);
  padding: 2px 6px;
  border-radius: 5px;
  white-space: nowrap;
}
:root[data-theme="dark"] .article :not(pre) > code { color: var(--accent); }

.note {
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  background: var(--paper);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin: 0 0 22px;
}
.note::before {
  content: "Note";
  display: block;
  font-size: 12px;
  letter-spacing: .09em;
  text-transform: uppercase;
  color: var(--brand);
  font-weight: 600;
  margin-bottom: 4px;
}
.note p { margin: 0; }

/* --- Code blocks ---------------------------------------------------------- */

.code-block {
  position: relative;
  margin: 0 0 24px;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--code-bg);
  border: 1px solid var(--code-line);
}
.code-block pre {
  margin: 0;
  padding: 18px 20px;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 13.8px;
  line-height: 1.68;
  color: var(--code-text);
  tab-size: 2;
}
.copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  font: inherit;
  font-size: 12px;
  font-family: var(--sans);
  padding: 4px 10px;
  border-radius: 6px;
  border: 1px solid #333b46;
  background: #1e242c;
  color: #9aa5b3;
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s ease;
}
.code-block:hover .copy-btn,
.copy-btn:focus-visible { opacity: 1; }
.copy-btn:hover { color: #fff; border-color: #4b5563; }

.tok-comment { color: #6f7b8c; font-style: italic; }
.tok-string  { color: #9ecb8a; }
.tok-keyword { color: #e08fc0; }
.tok-tag     { color: #7cc7e0; }
.tok-hook    { color: #f0c274; }
.tok-comp    { color: #f0c274; }
.tok-number  { color: #d7a4f0; }
.tok-attr    { color: #8fb8e8; }

/* --- Pager ---------------------------------------------------------------- */

.pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 56px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}
.pager a {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 18px;
  color: var(--ink);
}
.pager a:hover { border-color: var(--brand); text-decoration: none; }
.pager span {
  display: block;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .09em;
  color: var(--muted);
  margin-bottom: 3px;
}
.pager .next { text-align: right; grid-column: 2; }

/* --- Legal / plain pages -------------------------------------------------- */

.page { max-width: 760px; padding-top: 56px; }
.page h1 { font-size: clamp(30px, 4.4vw, 42px); letter-spacing: -0.034em; margin-bottom: 12px; }
.page .updated { color: var(--muted); font-size: 15px; margin: 0 0 34px; font-family: var(--mono); }
.page h2 { font-size: 22px; margin: 40px 0 12px; }
.page h3 { font-size: 17.5px; margin: 26px 0 8px; }
.page p { margin: 0 0 16px; }
.page ul { margin: 0 0 20px; padding-left: 22px; }
.page li { margin-bottom: 8px; }
.page .toc-legal {
  border: 1px solid var(--line);
  background: var(--paper);
  border-radius: var(--radius);
  padding: 18px 24px;
  margin-bottom: 36px;
}
.page .toc-legal ol { margin: 0; padding-left: 20px; font-size: 15px; }

.error-page { text-align: center; padding: 110px 0 40px; }
.error-page .code404 {
  font-family: var(--mono);
  font-size: 15px;
  color: var(--brand);
  letter-spacing: .1em;
}
.error-page h1 { font-size: clamp(30px, 5vw, 44px); margin: 10px 0 14px; }
.error-page p { max-width: 46ch; margin: 0 auto 26px; color: var(--muted); }

/* --- Responsive ----------------------------------------------------------- */

@media (max-width: 1000px) {
  .hero-grid { grid-template-columns: 1fr; gap: 40px; }
  .hero { padding-top: 48px; }
  .guide-layout { grid-template-columns: 1fr; gap: 28px; }
  .toc { display: none; }
  .toc-mobile { display: block; margin-bottom: 8px; }
  .toc-mobile summary {
    cursor: pointer;
    padding: 12px 16px;
    border: 1px solid var(--line);
    border-radius: var(--radius);
    background: var(--paper);
    font-weight: 600;
    color: var(--ink);
  }
  .toc-mobile[open] summary { border-radius: var(--radius) var(--radius) 0 0; }
  .toc-mobile .toc {
    display: block;
    position: static;
    max-height: none;
    border: 1px solid var(--line);
    border-top: none;
    border-radius: 0 0 var(--radius) var(--radius);
    padding: 14px 16px;
  }
  .toc-mobile .toc h2 { display: none; }
}

@media (max-width: 720px) {
  body { font-size: 16.5px; }
  .wrap { padding-inline: 18px; }

  /* No JavaScript: the header wraps and the links sit on their own row. */
  .header-inner { flex-wrap: wrap; height: auto; padding-block: 10px; row-gap: 8px; }
  .site-nav { flex-basis: 100%; order: 3; }
  .site-nav ul { flex-wrap: wrap; gap: 2px; }
  .site-nav a { padding: 8px 10px; }

  /* With JavaScript: collapse behind the menu button. */
  :root.js .header-inner { flex-wrap: nowrap; height: 64px; padding-block: 0; }
  :root.js .nav-toggle { display: inline-grid; }
  :root.js .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 64px;
    background: var(--surface);
    border-bottom: 1px solid var(--line);
    padding: 10px 18px 16px;
    box-shadow: var(--shadow);
  }
  :root.js .site-nav.is-open { display: block; }
  :root.js .site-nav ul { flex-direction: column; align-items: stretch; }
  :root.js .site-nav a { padding: 11px 12px; font-size: 16px; }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; padding-top: 36px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { grid-column: 1; text-align: left; }
  .article h2 { font-size: 22px; margin-top: 36px; }
}

@media print {
  .site-header, .site-footer, .toc, .toc-mobile, .pager, .copy-btn { display: none; }
  body { font-size: 11pt; }
  .code-block { border: 1px solid #ccc; }
}