:root {
  --bg: #000000;
  --surface: #111113;
  --text: #f2f2f2;
  --muted: #9a9a9a;
  --border: #2a2a2a;
  --accent: #ffffff;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN",
    "Yu Gothic", Meiryo, sans-serif;
  line-height: 1.8;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 20px 80px;
}

header.site {
  border-bottom: 1px solid var(--border);
  padding: 18px 20px;
  position: sticky;
  top: 0;
  background: rgba(0, 0, 0, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
}

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

.wordmark {
  font-style: italic;
  font-weight: 800;
  font-size: 22px;
  letter-spacing: -0.5px;
  color: var(--text);
  text-decoration: none;
}

.nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  margin-left: 16px;
}
.nav a:hover { color: var(--text); }

h1 {
  font-size: 28px;
  font-weight: 800;
  margin: 8px 0 4px;
  letter-spacing: -0.5px;
}

h2 {
  font-size: 19px;
  font-weight: 700;
  margin: 40px 0 10px;
  padding-top: 24px;
  border-top: 1px solid var(--border);
}

h3 {
  font-size: 16px;
  font-weight: 700;
  margin: 26px 0 4px;
  color: var(--text);
}

p, li { color: var(--text); }

ol, ul { padding-left: 22px; }
li { margin: 6px 0; }

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

strong { font-weight: 700; }

.updated {
  color: var(--muted);
  font-size: 14px;
  margin-bottom: 8px;
}

.lead { color: var(--muted); }

table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
  font-size: 15px;
}
th, td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
th { background: var(--surface); }

.faq h3::before {
  content: "Q. ";
  color: var(--muted);
}

footer.site {
  max-width: 720px;
  margin: 0 auto;
  padding: 28px 20px 60px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 14px;
}
footer.site a { color: var(--muted); margin-right: 16px; }
footer.site a:hover { color: var(--text); }

/* 招待リンク / 友達リンクの未インストール時フォールバック */
.landing {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 40px 24px;
  gap: 8px;
}
.landing .wordmark { font-size: 28px; margin-bottom: 24px; }
.landing h1 { font-size: 24px; margin: 0; }
.landing .sub { color: var(--muted); margin: 4px 0 28px; }
.landing .cta {
  display: inline-block;
  width: 100%;
  max-width: 320px;
  padding: 15px 20px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 16px;
  text-decoration: none;
  margin: 6px 0;
}
.landing .cta.primary { background: var(--accent); color: #000; }
.landing .cta.secondary { background: var(--surface); color: var(--text); border: 1px solid var(--border); }