:root {
    --ground: #F7F8F6;
    --surface: #FFFFFF;
    --surface2: #F0F3F0;
    --ink: #1B2420;
    --ink2: #4B564F;
    --ink3: #79857E;
    --line: #E1E6E1;
    --accent: #1F6FB2;
    --accent-soft: #E5F0FA;
    --accent-deep: #164F80;
  }
  @media (prefers-color-scheme: dark) {
    :root {
      --ground: #101512;
      --surface: #171D19;
      --surface2: #1D2420;
      --ink: #EAF0EC;
      --ink2: #B8C4BC;
      --ink3: #7E8B84;
      --line: #26302A;
      --accent: #5AA9E6;
      --accent-soft: #16304A;
      --accent-deep: #9CCBF2;
    }
  }
  * { box-sizing: border-box; }
  body {
    margin: 0;
    background: var(--ground);
    color: var(--ink);
    font-family: "Noto Sans JP", "Hiragino Sans", system-ui, sans-serif;
    line-height: 1.9;
    -webkit-font-smoothing: antialiased;
  }
  img { max-width: 100%; }
  .page {
    max-width: 760px;
    margin: 0 auto;
    padding: 56px 24px 96px;
  }
  header.top {
    display: flex;
    align-items: center;
    gap: 14px;
    margin-bottom: 8px;
  }
  .mark {
    width: 40px; height: 40px;
    border-radius: 11px;
    background: var(--accent);
    color: #fff;
    display: flex; align-items: center; justify-content: center;
    font-family: "Zen Maru Gothic", sans-serif;
    font-weight: 700;
    font-size: 17px;
    flex: none;
  }
  .brand {
    font-family: "Zen Maru Gothic", sans-serif;
    font-weight: 500;
    font-size: 13.5px;
    color: var(--ink3);
    letter-spacing: 0.02em;
  }
  h1 {
    font-family: "Zen Maru Gothic", sans-serif;
    font-weight: 700;
    font-size: clamp(26px, 4.5vw, 34px);
    line-height: 1.3;
    margin: 18px 0 6px;
    text-wrap: balance;
  }
  .h1-en {
    font-family: "Zen Maru Gothic", sans-serif;
    font-weight: 500;
    font-size: 15px;
    color: var(--ink3);
    margin: 0 0 22px;
  }
  .meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 18px;
    font-size: 12.5px;
    color: var(--ink3);
    padding-bottom: 26px;
    border-bottom: 1px solid var(--line);
    margin-bottom: 30px;
  }
  .meta b { color: var(--ink2); font-weight: 600; }
  .block a, .note a { color: var(--accent-deep); text-decoration-thickness: 1px; }
  .block a:hover, .note a:hover { text-decoration-thickness: 2px; }
  .lead {
    background: var(--accent-soft);
    border: 1px solid color-mix(in srgb, var(--accent) 30%, transparent);
    border-radius: 14px;
    padding: 18px 20px;
    margin-bottom: 36px;
  }
  .lead p { margin: 0; }
  .lead .ja { font-size: 15px; font-weight: 500; color: var(--ink); }
  .lead .en { font-size: 12.5px; color: var(--ink2); margin-top: 6px; }
  nav.toc { margin-bottom: 44px; }
  nav.toc .toc-label {
    font-family: "Zen Maru Gothic", sans-serif;
    font-size: 11.5px;
    font-weight: 700;
    letter-spacing: 0.08em;
    color: var(--ink3);
    text-transform: uppercase;
    margin-bottom: 10px;
  }
  nav.toc ol {
    list-style: none;
    margin: 0; padding: 0;
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 6px 20px;
  }
  nav.toc li a {
    display: block;
    font-size: 13.5px;
    color: var(--ink2);
    text-decoration: none;
    padding: 6px 0;
    border-bottom: 1px dashed var(--line);
  }
  nav.toc li a:hover { color: var(--accent-deep); }
  nav.toc li a span.num {
    color: var(--ink3);
    font-variant-numeric: tabular-nums;
    margin-right: 8px;
  }
  section {
    padding: 30px 0;
    border-bottom: 1px solid var(--line);
    scroll-margin-top: 20px;
  }
  section:last-of-type { border-bottom: none; }
  h2 {
    font-family: "Zen Maru Gothic", sans-serif;
    font-size: 19px;
    font-weight: 700;
    display: flex;
    align-items: baseline;
    gap: 10px;
    margin: 0 0 16px;
  }
  h2 .num {
    font-size: 13px;
    font-weight: 700;
    color: var(--accent-deep);
    background: var(--accent-soft);
    border-radius: 7px;
    padding: 3px 8px;
    font-variant-numeric: tabular-nums;
  }
  .block { margin-bottom: 16px; }
  .block:last-child { margin-bottom: 0; }
  .ja { font-size: 15px; color: var(--ink); }
  .en { font-size: 13px; color: var(--ink3); margin-top: 5px; line-height: 1.7; }
  ul.items { margin: 10px 0 0; padding-left: 0; list-style: none; }
  ul.items li {
    padding: 10px 0 10px 18px;
    border-top: 1px solid var(--line);
    position: relative;
  }
  ul.items li:first-child { border-top: none; }
  ul.items li::before {
    content: "";
    position: absolute;
    left: 2px; top: 19px;
    width: 5px; height: 5px;
    border-radius: 50%;
    background: var(--accent);
  }
  .note {
    margin-top: 14px;
    font-size: 12.5px;
    color: var(--ink3);
    background: var(--surface2);
    border-radius: 10px;
    padding: 12px 14px;
  }
  footer {
    margin-top: 40px;
    padding-top: 24px;
    border-top: 1px solid var(--line);
    font-size: 12px;
    color: var(--ink3);
  }
  @media (max-width: 520px) {
    nav.toc ol { grid-template-columns: 1fr; }
  }

  .apps { display: grid; gap: 14px; margin: 10px 0 0; }
  .app { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 18px 20px; }
  .app h3 { font-family: "Zen Maru Gothic", sans-serif; font-size: 17px; margin: 0 0 4px; }
  .app p { margin: 0; font-size: 14px; color: var(--ink2); }
  .app .links { margin-top: 10px; font-size: 13.5px; display: flex; flex-wrap: wrap; gap: 6px 16px; }
  .app .links a { color: var(--accent-deep); }
  .badge { display: inline-block; font-size: 11.5px; font-weight: 700; color: var(--accent-deep); background: var(--accent-soft); border-radius: 6px; padding: 2px 8px; margin-left: 8px; vertical-align: 2px; }