:root {
  --paper: #f5f8ff;
  --paper-deep: #e8efff;
  --ink: #15213b;
  --muted: #5f6d88;
  --accent: #1769e0;
  --accent-deep: #0d4fad;
  --line: rgba(23, 105, 224, 0.16);
  --card: rgba(255, 255, 255, 0.86);
}

* { box-sizing: border-box; }
html { color-scheme: light; }
body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background:
    radial-gradient(circle at 12% 4%, rgba(23, 105, 224, 0.14), transparent 25rem),
    linear-gradient(155deg, var(--paper), #fff 54%, var(--paper-deep));
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  line-height: 1.85;
  overflow-x: hidden;
}
a { color: var(--accent-deep); }
a:hover { text-decoration-thickness: 2px; }
a:focus-visible { outline: 3px solid rgba(23, 105, 224, 0.35); outline-offset: 4px; }
.shell { width: min(820px, calc(100% - 32px)); margin: 0 auto; padding: 28px 0 72px; }
.masthead { display: flex; align-items: center; justify-content: space-between; gap: 24px; padding: 8px 0 32px; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 11px; color: var(--ink); font-size: 18px; font-weight: 800; letter-spacing: .02em; text-decoration: none; }
.brand-mark { display: grid; width: 38px; height: 38px; place-items: center; border-radius: 13px; color: #fff; background: var(--accent); box-shadow: 0 10px 24px rgba(13, 79, 173, .24); }
nav { display: flex; flex-wrap: wrap; gap: 16px; font-size: 13px; }
nav a { color: var(--muted); text-decoration: none; }
nav a[aria-current="page"] { color: var(--accent-deep); font-weight: 700; }
main { min-width: 0; margin-top: 38px; padding: clamp(24px, 5vw, 52px); border: 1px solid var(--line); border-radius: 28px; background: var(--card); box-shadow: 0 24px 70px rgba(21, 33, 59, .09); backdrop-filter: blur(16px); }
.eyebrow { margin: 0 0 8px; color: var(--accent-deep); font-size: 12px; font-weight: 800; letter-spacing: .15em; text-transform: uppercase; }
h1 { margin: 0; font-size: clamp(30px, 6vw, 48px); line-height: 1.25; letter-spacing: -.04em; }
.updated { margin: 10px 0 34px; color: var(--muted); font-size: 13px; }
h2 { margin: 36px 0 10px; font-size: 19px; line-height: 1.5; }
p, li { overflow-wrap: anywhere; font-size: 15px; }
ul { padding-left: 1.4em; }
li + li { margin-top: 6px; }
.lead { margin: 18px 0 0; color: var(--muted); font-size: 16px; }
.card { margin-top: 24px; padding: 22px; border: 1px solid var(--line); border-radius: 20px; background: rgba(245, 248, 255, .72); }
.card h2 { margin-top: 0; }
.button { display: inline-flex; min-height: 48px; align-items: center; justify-content: center; margin-top: 8px; padding: 0 20px; border-radius: 999px; color: #fff; background: var(--accent-deep); font-weight: 700; text-decoration: none; }
footer { padding: 28px 4px 0; color: var(--muted); font-size: 12px; }
@media (max-width: 620px) { .masthead { align-items: flex-start; flex-direction: column; } main { margin-top: 24px; border-radius: 22px; } }
@media (prefers-reduced-motion: no-preference) { main { animation: arrive 420ms ease-out both; } @keyframes arrive { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } } }