:root {
  color-scheme: dark;
  --bg: #070b12;
  --ink: #eef3f8;
  --muted: #94a7b9;
  --line: rgba(255, 255, 255, 0.12);
  --teal: #46e6d3;
  --serif: "Times New Roman", "Hiragino Mincho ProN", YuMincho, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Hiragino Sans", "Noto Sans JP", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--bg);
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 14% 8%, rgba(70, 230, 211, 0.1), transparent 32rem),
    linear-gradient(180deg, #09111b, var(--bg));
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
}

.shell {
  width: min(780px, calc(100% - 44px));
  margin: 0 auto;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 94px;
  border-bottom: 1px solid var(--line);
}

.brand {
  text-decoration: none;
  font-weight: 750;
  letter-spacing: 0.04em;
}

.brand b,
.back,
main a {
  color: var(--teal);
}

.back {
  font-size: 0.78rem;
  text-decoration: none;
}

main {
  padding: clamp(62px, 10vw, 118px) 0 110px;
}

.eyebrow,
.updated {
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.16em;
}

h1 {
  margin: 18px 0 56px;
  font-family: var(--serif);
  font-size: clamp(2.6rem, 8vw, 5.2rem);
  font-weight: 500;
  line-height: 1.06;
}

section {
  margin-top: 42px;
  padding-top: 32px;
  border-top: 1px solid var(--line);
}

h2 {
  margin: 0 0 14px;
  font-size: 1.02rem;
}

p,
li {
  color: #c8d4de;
  font-size: 0.92rem;
  line-height: 1.95;
}

ul {
  padding-left: 1.4em;
}

.updated {
  margin-top: 58px;
}

footer {
  padding: 30px 0 46px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.72rem;
}

@media (max-width: 520px) {
  header {
    align-items: flex-start;
    flex-direction: column;
    justify-content: center;
  }
}