:root {
  --ink: #1c1915;
  --muted: #5c564c;
  --paper: #f4efe6;
  --card: #fffdf8;
  --line: #e2d9cc;
  --amber: #9a4e12;
  --amber-soft: #f3e1d0;
  --green: #234237;
  --green-soft: #e5efe9;
  --warn: #8c2f24;
  --warn-soft: #f8e6e2;
  --shadow: 0 16px 40px rgba(28, 25, 21, 0.06);
  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --sans: "Segoe UI", "PingFang SC", "Noto Sans SC", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(900px 420px at 100% -10%, #f7e7d4 0%, transparent 55%),
    var(--paper);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.6;
}
a { color: var(--amber); }
a:hover { color: var(--ink); }
img { max-width: 100%; }

.skip {
  position: absolute;
  left: 12px;
  top: -40px;
  background: var(--ink);
  color: white;
  padding: 8px 12px;
  z-index: 5;
}
.skip:focus { top: 12px; }

.wrap { width: min(1080px, calc(100% - 32px)); margin: 0 auto; }
.narrow { width: min(740px, calc(100% - 32px)); margin: 0 auto; }

.top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 18px 0 8px;
}
.brand {
  font-family: var(--serif);
  color: var(--ink);
  text-decoration: none;
  font-size: 22px;
  letter-spacing: -0.03em;
}
.brand span { color: var(--amber); }
.nav { display: flex; flex-wrap: wrap; gap: 8px 16px; }
.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 15px;
}
.nav a[aria-current="page"], .nav a:hover { color: var(--ink); }

.notice {
  margin: 12px 0 0;
  padding: 10px 14px;
  background: var(--amber-soft);
  border-radius: 10px;
  color: #5c3412;
  font-size: 14px;
}

.hero { padding: 42px 0 20px; display: grid; grid-template-columns: 1.3fr 0.7fr; gap: 36px; align-items: center; }
.kicker {
  margin: 0 0 10px;
  font-size: 13px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--amber);
}
h1, h2, h3 { font-family: var(--serif); font-weight: 600; letter-spacing: -0.03em; line-height: 1.15; }
h1 { font-size: clamp(40px, 6vw, 64px); margin: 0 0 16px; }
h2 { font-size: 32px; margin: 28px 0 12px; }
.section > h2:first-of-type { margin-top: 0; }
h3 { font-size: 22px; margin: 0 0 8px; }
.lede { font-size: 19px; color: #3a342c; margin: 0 0 22px; }

.actions { display: flex; flex-wrap: wrap; gap: 10px; }
.btn {
  display: inline-block;
  text-decoration: none;
  border-radius: 999px;
  padding: 11px 16px;
  font-size: 15px;
}
.btn.primary { background: var(--ink); color: #f7f2ea; }
.btn.primary:hover { background: var(--amber); color: white; }
.btn.ghost { border: 1px solid var(--line); color: var(--ink); background: transparent; }

.hero-figure { margin: 0; }
.hero-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 18px;
  box-shadow: var(--shadow);
}

.bezel {
  background: #141210;
  border-radius: 18px;
  padding: 14px;
  box-shadow: var(--shadow);
}
.screen {
  background: radial-gradient(120px 80px at 50% 28%, #3a342c, #0c0b0a 70%);
  min-height: 230px;
  border-radius: 8px;
  position: relative;
  overflow: hidden;
}
.shelf {
  position: absolute;
  left: 22px;
  top: 36px;
  color: #f4efe6;
  font-family: var(--serif);
  font-size: 28px;
}
.shelf small { display: block; margin-top: 6px; font-family: var(--sans); font-size: 13px; color: #c8bfb2; }
.dock {
  position: absolute;
  left: 16px;
  right: 16px;
  bottom: 16px;
  display: flex;
  gap: 8px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 14px;
  padding: 10px;
}
.dock i {
  flex: 1;
  height: 36px;
  border-radius: 8px;
  background: #d7c3a4;
}
.dock i:nth-child(2) { background: #8ea58f; }
.dock i:nth-child(3) { background: #c47b62; }
.dock i:nth-child(4) { background: #7f8ea3; }

.section { padding: 28px 0 10px; }
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.card, .lesson, .os, .qa {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 18px 18px 16px;
  box-shadow: var(--shadow);
}
.card p, .lesson p, .os p { margin: 0; color: var(--muted); }
.num {
  font-family: var(--serif);
  color: var(--amber);
  font-size: 14px;
}

table { width: 100%; border-collapse: collapse; background: var(--card); border-radius: 16px; overflow: hidden; }
th, td { text-align: left; padding: 14px 16px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font-size: 13px; letter-spacing: 0.06em; text-transform: uppercase; color: var(--muted); background: #faf7f2; }
tr:last-child td { border-bottom: 0; }
.yes { color: var(--green); font-weight: 650; }
.no { color: var(--warn); font-weight: 650; }

.stack { display: grid; gap: 12px; }
.callout {
  border-left: 4px solid var(--warn);
  background: var(--warn-soft);
  padding: 14px 16px;
  border-radius: 0 12px 12px 0;
}
.callout strong { color: var(--warn); }
.ok {
  border-left: 4px solid var(--green);
  background: var(--green-soft);
  padding: 14px 16px;
  border-radius: 0 12px 12px 0;
}

pre {
  background: #1c1915;
  color: #f4efe6;
  padding: 14px 16px;
  border-radius: 12px;
  overflow-x: auto;
  font-size: 14px;
  line-height: 1.55;
}
code { font-family: Consolas, "Cascadia Mono", ui-monospace, monospace; }
ol.steps { margin: 0; padding-left: 20px; }
ol.steps li { margin: 0 0 12px; }
ol.steps li span { color: var(--muted); }

.crumbs {
  margin: 22px 0 14px;
  font-size: 14px;
  color: var(--muted);
}
.crumbs a { color: var(--muted); text-decoration: none; }
.crumbs a:hover { color: var(--ink); }
.crumbs [aria-current="page"] { color: var(--ink); }

.faq { display: grid; gap: 10px; }
details {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px 16px;
}
summary { cursor: pointer; }
summary h2 {
  display: inline;
  font-family: var(--sans);
  font-size: 17px;
  font-weight: 650;
  letter-spacing: 0;
  line-height: 1.4;
  margin: 0;
}
details p { margin: 8px 0 0; color: var(--muted); }

.footer {
  margin-top: 48px;
  padding: 22px 0 36px;
  color: var(--muted);
  font-size: 14px;
  border-top: 1px solid var(--line);
}
.footer a { color: var(--muted); }
.footnav { display: flex; flex-wrap: wrap; gap: 8px 16px; margin: 0 0 12px; }
.footnav a { text-decoration: none; }
.footnav a:hover { color: var(--ink); }
.updated { margin: 8px 0 0; }

@media (max-width: 800px) {
  .hero, .grid { grid-template-columns: 1fr; }
  .top { align-items: flex-start; flex-direction: column; }
  h1 { font-size: 38px; }
}