:root {
  --bg: #fbfcff;
  --bg2: #f4f7ff;
  --text: #0f0f10;
  --text-faint: rgba(15, 15, 16, 0.48);
  --line: rgba(15, 15, 16, 0.10);
  --container: 820px;
  --pageY: 72px;
  --pageX: 22px;
  --font: "Noto Sans JP", system-ui, -apple-system, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

html,
body { height: 100%; }

body {
  font-family: var(--font);
  margin: 0;
  padding: var(--pageY) var(--pageX);
  background: var(--bg);
  color: var(--text);
  line-height: var(--lh, 1.8);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  position: relative;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(1100px 520px at 18% -12%, rgba(43, 108, 255, 0.10), transparent 62%),
    radial-gradient(1200px 620px at 78% 112%, rgba(43, 108, 255, 0.08), transparent 60%),
    linear-gradient(180deg, var(--bg), var(--bg2));
}

.container {
  max-width: var(--container);
  margin: 0 auto;
  animation: fadeIn 0.6s ease-out both;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

a {
  color: inherit;
  text-decoration: none;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
textarea:focus-visible {
  outline: 2px solid rgba(15, 15, 16, 0.22);
  outline-offset: 4px;
  border-radius: 12px;
}

.back {
  display: inline-flex;
  align-items: center;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid transparent;
  color: rgba(15, 15, 16, 0.62);
  margin-top: 18px;
  transition: background 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
  font-weight: 700;
  font-size: 12.5px;
  letter-spacing: 0.02em;
}

.back:hover {
  background: rgba(15, 15, 16, 0.03);
  border-color: rgba(15, 15, 16, 0.10);
  transform: translateY(-1px);
}

footer {
  margin-top: 64px;
  padding-top: 18px;
  border-top: 1px solid rgba(15, 15, 16, 0.10);
  color: var(--text-faint);
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.02em;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.footer-link {
  display: inline-flex;
  align-items: center;
  padding: 8px 10px;
  border-radius: 12px;
  border: 1px solid transparent;
  color: rgba(15, 15, 16, 0.62);
  transition: background 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
  white-space: nowrap;
}

.footer-link:hover {
  background: rgba(15, 15, 16, 0.03);
  border-color: rgba(15, 15, 16, 0.10);
  transform: translateY(-1px);
}

@media (prefers-reduced-motion: reduce) {
  .container { animation: none; }
  .back,
  .footer-link { transition: none; }
}