:root {
  --bg: #ffffff;
  --fg: #1d1d1f;
  --muted: #6e6e73;
  --accent: #1a8054;
  --accent-light: #e8f5ee;
  --border: #e5e5e7;
  --card-bg: #fafafa;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1c1e;
    --fg: #f5f5f7;
    --muted: #a1a1a6;
    --accent: #4cb583;
    --accent-light: #1f2c25;
    --border: #38383a;
    --card-bg: #2c2c2e;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  padding: 0;
  font-family:
    -apple-system, BlinkMacSystemFont, "Helvetica Neue",
    "Hiragino Sans", "Hiragino Kaku Gothic ProN",
    "Noto Sans JP", "Yu Gothic", "Meiryo", sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}
.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 32px 24px 80px;
}

/* ========== Header ========== */
header.page-header {
  padding-bottom: 20px;
  margin-bottom: 28px;
  border-bottom: 1px solid var(--border);
}
header.page-header .app-name {
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0.1em;
  font-weight: 600;
  margin-bottom: 6px;
}
header.page-header h1 {
  font-size: 30px;
  font-weight: 700;
  margin: 0 0 8px;
  letter-spacing: -0.01em;
}
header.page-header .meta {
  font-size: 13px;
  color: var(--muted);
}

/* ========== Sections ========== */
h2 {
  font-size: 19px;
  font-weight: 600;
  margin: 36px 0 10px;
  color: var(--fg);
}
h2::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 18px;
  background: var(--accent);
  border-radius: 2px;
  vertical-align: -2px;
  margin-right: 10px;
}

h3 {
  font-size: 16px;
  font-weight: 600;
  margin: 24px 0 6px;
}

p { margin: 8px 0 16px; }
ul { padding-left: 22px; margin: 8px 0 16px; }
li { margin-bottom: 6px; }

a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}
a:hover { text-decoration: none; }

/* ========== Top page (index) ========== */
.hero {
  text-align: center;
  padding: 32px 0 24px;
}
.hero .app-name-big {
  font-size: 48px;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin: 0 0 12px;
  color: var(--accent);
}
.hero .tagline {
  font-size: 17px;
  color: var(--muted);
  margin-bottom: 0;
}
.cards {
  display: grid;
  gap: 16px;
  margin-top: 36px;
}
.card {
  display: block;
  padding: 20px 22px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--card-bg);
  text-decoration: none;
  color: var(--fg);
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.card:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}
.card .card-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--fg);
}
.card .card-desc {
  font-size: 13px;
  color: var(--muted);
}

/* ========== FAQ (support) ========== */
.faq-item {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 18px;
  margin-bottom: 12px;
  background: var(--card-bg);
}
.faq-q {
  font-weight: 600;
  margin-bottom: 6px;
  font-size: 15px;
}
.faq-a {
  font-size: 14px;
  color: var(--fg);
  margin: 0;
}

/* ========== Callout ========== */
.callout {
  background: var(--accent-light);
  border-left: 3px solid var(--accent);
  padding: 12px 16px;
  border-radius: 6px;
  margin: 16px 0 20px;
  font-size: 14px;
}

/* ========== Footer ========== */
footer.page-footer {
  margin-top: 56px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  font-size: 13px;
  color: var(--muted);
  text-align: center;
}
footer.page-footer .back-link {
  display: inline-block;
  margin-bottom: 12px;
}