:root {
  --card: #ffffff;
  --fg: #0f172a;
  --muted: #475569;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  min-height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
    "Yu Gothic UI", Meiryo, sans-serif;
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  color: var(--fg);
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  position: relative;
}

.lang-switch {
  position: absolute;
  top: 16px;
  right: 16px;
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.lang-switch button {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.25);
  background: rgba(255, 255, 255, 0.08);
  color: #e2e8f0;
  font-size: 12px;
  padding: 6px 10px;
  border-radius: 9999px;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease;
}

.lang-switch button:hover { background: rgba(255, 255, 255, 0.18); }
.lang-switch button[aria-pressed="true"] {
  background: #fff;
  color: #0f172a;
  border-color: #fff;
}

.card {
  background: var(--card);
  border-radius: 16px;
  padding: 48px 32px;
  max-width: 560px;
  width: 100%;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.25);
  text-align: center;
}

.title {
  margin: 0 0 20px;
  font-size: clamp(20px, 3.4vw, 26px);
  line-height: 1.5;
  color: var(--fg);
}

.lead {
  margin: 0 0 28px;
  font-size: 15px;
  line-height: 1.7;
  color: var(--muted);
}

.btn {
  display: inline-block;
  padding: 14px 32px;
  background: var(--accent);
  color: #fff;
  font-weight: 600;
  text-decoration: none;
  border-radius: 9999px;
  transition: background 0.15s ease;
}

.btn:hover { background: var(--accent-hover); }