:root {
  color-scheme: light;
  --ink: #234c63;
  --muted: #587385;
  --sea: #e8f8ff;
  --card: rgba(255, 255, 255, 0.9);
  --line: #c8e6f2;
  --accent: #2689a9;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 12% 8%, rgba(255,255,255,.95) 0 6%, transparent 7%),
    linear-gradient(180deg, #dff6ff 0%, #f7fcff 55%, #e9f8f5 100%);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", sans-serif;
  line-height: 1.8;
}

main {
  width: min(760px, calc(100% - 32px));
  margin: 0 auto;
  padding: 40px 0 64px;
}

header, section {
  margin-bottom: 20px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 22px;
  background: var(--card);
  box-shadow: 0 12px 28px rgba(60, 124, 150, .08);
}

h1 { margin: 0 0 8px; font-size: clamp(1.7rem, 6vw, 2.4rem); line-height: 1.35; }
h2 { margin: 0 0 8px; font-size: 1.15rem; }
p, ul { margin: 8px 0 0; }
ul { padding-left: 1.4rem; }
a { color: var(--accent); }
.eyebrow { margin: 0 0 4px; color: var(--accent); font-weight: 700; }
.updated, .note { color: var(--muted); font-size: .92rem; }
.placeholder {
  padding: 12px 14px;
  border: 2px dashed #df8c8c;
  border-radius: 12px;
  color: #8d3434;
  background: #fff7f7;
  font-weight: 700;
}
nav { margin-top: 18px; display: flex; flex-wrap: wrap; gap: 8px 16px; }
footer { padding: 8px 4px; color: var(--muted); text-align: center; font-size: .88rem; }

@media (max-width: 520px) {
  main { width: min(100% - 20px, 760px); padding-top: 20px; }
  header, section { padding: 19px; border-radius: 18px; }
}