:root {
  --color-bg: #ffffff;
  --color-text: #111111;
  --color-text-secondary: #707072;
  --color-link: #1151ff;
  --color-border: #cacacb;
  --color-surface: #fafafa;
}

* {
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  padding: 0;
  font-family:
    -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Hiragino Sans",
    "Yu Gothic", system-ui, sans-serif;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
}

header {
  border-bottom: 1px solid var(--color-border);
  padding: 16px 0;
}

.header-inner {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

a.logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-text);
  text-decoration: none;
  letter-spacing: -0.02em;
}

nav.global-nav {
  display: flex;
  gap: 16px;
  font-size: 0.9rem;
}

nav.global-nav a {
  color: var(--color-text-secondary);
  text-decoration: none;
}

nav.global-nav a:hover {
  color: var(--color-text);
}

main {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}

h1 {
  font-size: 1.75rem;
  line-height: 1.3;
  margin: 0 0 8px;
  letter-spacing: -0.02em;
}

h2 {
  font-size: 1.25rem;
  line-height: 1.4;
  margin: 32px 0 12px;
  letter-spacing: -0.01em;
}

h3 {
  font-size: 1.05rem;
  margin: 20px 0 8px;
}

p,
li {
  font-size: 1rem;
  margin: 0 0 12px;
}

ul,
ol {
  padding-left: 1.5em;
}

a {
  color: var(--color-link);
}

.subtitle {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
  margin-bottom: 24px;
}

.meta {
  color: var(--color-text-secondary);
  font-size: 0.85rem;
  margin-bottom: 24px;
}

.divider {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 32px 0;
}

footer {
  border-top: 1px solid var(--color-border);
  padding: 24px;
  margin-top: 64px;
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 0.85rem;
}

footer nav {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-bottom: 8px;
}

footer nav a {
  color: var(--color-text-secondary);
  text-decoration: none;
}

@media (max-width: 480px) {
  .header-inner {
    padding: 0 16px;
  }
  main {
    padding: 24px 16px 48px;
  }
  h1 {
    font-size: 1.5rem;
  }
}