:root {
  --bg: #f3f6f4;
  --ink: #1c2b24;
  --accent: #0f6b4c;
  --muted: #5b6b63;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Hiragino Sans", "Noto Sans JP", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(15, 107, 76, 0.12), transparent 40%),
    linear-gradient(180deg, #eef5f1 0%, var(--bg) 100%);
  min-height: 100vh;
}

header,
main,
footer {
  width: min(720px, 92vw);
  margin: 0 auto;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 2rem 0 1rem;
}

.brand {
  margin: 0;
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--accent);
}

nav a {
  margin-left: 1rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 2px solid transparent;
}

nav a:hover {
  border-bottom-color: var(--accent);
}

main {
  padding: 1.5rem 0 3rem;
}

h1 {
  font-size: 2rem;
  margin-bottom: 0.75rem;
}

p {
  line-height: 1.7;
  color: var(--muted);
}

code {
  background: rgba(15, 107, 76, 0.1);
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
  color: var(--ink);
}

footer {
  padding-bottom: 2rem;
  font-size: 0.85rem;
  color: var(--muted);
}