:root {
  --bg: #ffffff;
  --bg-sub: #f5f6f8;
  --border: #dde1e6;
  --text: #1f2328;
  --text-sub: #6a737d;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --code-bg: #f6f8fa;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16181d;
    --bg-sub: #1e2127;
    --border: #33373f;
    --text: #e6e8eb;
    --text-sub: #9aa1ab;
    --accent: #3b82f6;
    --accent-hover: #60a5fa;
    --code-bg: #23262d;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Noto Sans JP", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.9;
  font-size: 15px;
}

.site-nav {
  max-width: 820px;
  margin: 0 auto;
  padding: 20px 24px 0;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-sub);
  text-decoration: none;
}
.back-link:hover { color: var(--accent); }

/* ---- hero ---- */

.hero {
  max-width: 820px;
  margin: 0 auto;
  padding: 48px 24px 56px;
  text-align: center;
}

.hero-icon { border-radius: 16px; }

.hero h1 {
  margin: 18px 0 12px;
  font-size: 30px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

.lead {
  margin: 0 auto;
  max-width: 620px;
  color: var(--text-sub);
  font-size: 14.5px;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-top: 28px;
  flex-wrap: wrap;
}

.button {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
}
.button:hover { border-color: var(--accent); color: var(--accent); }

.button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.button.primary:hover { background: var(--accent-hover); color: #fff; }

.hero-meta {
  margin-top: 14px;
  font-size: 12px;
  color: var(--text-sub);
}

/* ---- sections ---- */

main {
  max-width: 820px;
  margin: 0 auto;
  padding: 0 24px 40px;
}

section { margin-bottom: 72px; }

h2 {
  font-size: 21px;
  font-weight: 700;
  margin: 0 0 20px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border);
}

h3 { font-size: 16px; font-weight: 700; margin: 0 0 8px; }

p { margin: 0 0 12px; }

a { color: var(--accent); }

code {
  font-family: "SFMono-Regular", Consolas, Menlo, monospace;
  font-size: 0.9em;
  background: var(--code-bg);
  padding: 2px 6px;
  border-radius: 4px;
}

pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  overflow-x: auto;
  line-height: 1.7;
}
pre code { background: none; padding: 0; font-size: 12.5px; }

.note { font-size: 13px; color: var(--text-sub); }

/* features */

.features {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px 32px;
}

.features li {
  padding: 16px 0;
}

.features p { margin: 0; font-size: 13.5px; color: var(--text-sub); }

/* install steps */

.steps {
  margin: 0 0 14px;
  padding-left: 0;
  list-style: none;
  counter-reset: step;
}

.steps li {
  counter-increment: step;
  position: relative;
  padding: 6px 0 6px 44px;
}

.steps li::before {
  content: counter(step);
  position: absolute;
  left: 0;
  top: 8px;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* usage */

.usage-step { margin-bottom: 48px; }

.step-no {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent);
  color: #fff;
  font-size: 13px;
  margin-right: 10px;
  flex-shrink: 0;
}

figure {
  margin: 20px 0 0;
  text-align: center;
}

figure img {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--border);
  border-radius: 10px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.06);
}

figure .img-narrow { max-width: min(420px, 100%); }

figcaption {
  display: block;
  margin-top: 10px;
  font-size: 12px;
  color: var(--text-sub);
}

.figure-pair {
  display: flex;
  gap: 20px;
  justify-content: center;
  align-items: flex-start;
  flex-wrap: wrap;
}

.figure-pair > span { flex: 1 1 280px; max-width: 360px; }
.figure-pair img { width: 100%; }

/* footer */

.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-sub);
  text-align: center;
  padding: 48px 24px 40px;
}

.site-footer p { margin-top: 18px; font-size: 13px; }

@media (max-width: 640px) {
  .site-nav { padding: 16px 20px 0; }
  .hero { padding: 32px 20px 40px; }
  .hero h1 { font-size: 24px; }
  .hero-actions { flex-direction: column; align-items: stretch; }
  .hero-actions .button { justify-content: center; }
  main { padding: 0 20px 32px; }
  section { margin-bottom: 52px; }
  .features { grid-template-columns: 1fr; }
  .features li { padding: 12px 0; }
  .usage-step { margin-bottom: 36px; }
  pre { padding: 14px 16px; }
  .site-footer { padding: 36px 20px 32px; }
}