:root {
  color-scheme: light dark;
  --bg: #f8fbf8;
  --surface: rgba(255, 255, 255, 0.86);
  --ink: #20302b;
  --muted: #66746f;
  --line: rgba(42, 84, 69, 0.16);
  --leaf: #2f8d6a;
  --leaf-soft: #e4f4ec;
  --sky-soft: #edf7fb;
  --peach-soft: #fff3ee;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111816;
    --surface: rgba(25, 34, 31, 0.88);
    --ink: #edf7f2;
    --muted: #a9b8b2;
    --line: rgba(198, 230, 215, 0.18);
    --leaf: #64d2a1;
    --leaf-soft: rgba(67, 131, 99, 0.22);
    --sky-soft: rgba(74, 128, 150, 0.18);
    --peach-soft: rgba(167, 96, 72, 0.18);
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at 12% 6%, rgba(228, 244, 236, 0.85), transparent 30%),
    radial-gradient(circle at 88% 12%, rgba(237, 247, 251, 0.78), transparent 28%),
    var(--bg);
  color: var(--ink);
  font-family: "Hiragino Sans", "Yu Gothic", system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  line-height: 1.82;
  letter-spacing: 0;
}

main {
  width: min(920px, calc(100% - 32px));
  margin: 0 auto;
  padding: 56px 0 72px;
}

header {
  margin-bottom: 28px;
}

.mark {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 18px;
  color: var(--leaf);
  font-weight: 800;
}

.mark::before {
  content: "";
  width: 18px;
  height: 18px;
  border-radius: 999px;
  background: var(--leaf);
  box-shadow: 22px 0 0 rgba(47, 141, 106, 0.28), 44px 0 0 rgba(47, 141, 106, 0.14);
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 7vw, 3.3rem);
  line-height: 1.2;
  letter-spacing: 0;
}

.lead {
  max-width: 720px;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 1.04rem;
}

section,
.nav {
  margin-top: 18px;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 24px;
  box-shadow: 0 18px 42px rgba(23, 54, 42, 0.07);
}

section.soft {
  background: color-mix(in srgb, var(--leaf-soft) 68%, var(--surface));
}

section.sky {
  background: color-mix(in srgb, var(--sky-soft) 72%, var(--surface));
}

section.peach {
  background: color-mix(in srgb, var(--peach-soft) 72%, var(--surface));
}

h2 {
  margin: 0 0 10px;
  font-size: 1.16rem;
}

p {
  margin: 0 0 12px;
}

p:last-child,
ul:last-child,
ol:last-child {
  margin-bottom: 0;
}

ul,
ol {
  margin: 0 0 12px;
  padding-left: 1.25em;
}

a {
  color: var(--leaf);
  font-weight: 800;
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.18em;
}

.nav {
  display: grid;
  gap: 10px;
}

.nav a {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.5);
  color: var(--ink);
  text-decoration: none;
}

@media (prefers-color-scheme: dark) {
  .nav a {
    background: rgba(255, 255, 255, 0.04);
  }
}

.meta {
  margin-top: 28px;
  color: var(--muted);
  font-size: 0.92rem;
}

footer {
  margin-top: 28px;
  color: var(--muted);
  font-size: 0.92rem;
}