:root {
  --ink: #1e293b;
  --gray: #64748b;
  --line: #e2e8f0;
  --bg: #f8fafc;
  --accent: #2563eb;
  --maxw: 960px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: "Noto Sans JP", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.85;
  font-size: 15px;
}

img { max-width: 100%; display: block; height: auto; }

.demo-header {
  background: #fff;
  border-bottom: 1px solid var(--line);
  padding: 14px 20px;
  position: sticky;
  top: 0;
  z-index: 10;
}

.demo-header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.demo-tag {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .08em;
  color: var(--accent);
}

.demo-header h1 {
  font-size: 18px;
  font-weight: 800;
}

.demo-header a {
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.demo-main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 40px 20px 72px;
}

.demo-intro {
  margin-bottom: 28px;
}

.demo-intro h2 {
  font-size: clamp(22px, 4vw, 28px);
  font-weight: 800;
  margin-bottom: 10px;
}

.demo-intro p {
  color: var(--gray);
  font-size: 14px;
}

.demo-intro-lead {
  margin-top: 12px;
  font-size: 15px;
  font-weight: 700;
  color: var(--ink);
  line-height: 1.75;
}

.payment-chart {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 24px 20px 28px;
  box-shadow: 0 12px 40px rgba(15, 23, 42, .06);
}

.payment-chart__figure {
  margin: 0;
}

.payment-chart__figure img {
  width: 100%;
  height: auto;
  border-radius: 8px;
}

.payment-chart__caption {
  margin-top: 14px;
  font-size: 13px;
  color: var(--gray);
  text-align: center;
  line-height: 1.75;
}

.demo-note {
  margin-top: 28px;
  text-align: center;
  font-size: 15px;
  font-weight: 700;
  color: var(--accent);
}

@media (max-width: 680px) {
  .payment-chart {
    padding: 16px 12px 20px;
  }
}