/* 共通スタイル（本文・フッター・ボタン） */
:root {
  --color-bg: #f6f7fb;
  --color-surface: #ffffff;
  --color-text: #1f2937;
  --color-muted: #5b6475;
  --color-border: #dfe3ec;
  --color-primary: #4f46e5;
  --color-primary-hover: #4338ca;
  --color-primary-soft: #eef0ff;
  --color-danger: #b42318;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.06), 0 4px 16px rgba(15, 23, 42, 0.06);
  --container: 1120px;
  --font: system-ui, -apple-system, "Segoe UI", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic UI", Meiryo, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.75;
}

[hidden] { display: none !important; }

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

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 16px;
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0);
  white-space: nowrap; border: 0;
}

.skip-link {
  position: absolute;
  left: 8px; top: -48px;
  padding: 8px 12px;
  background: var(--color-surface);
  border-radius: var(--radius-sm);
  z-index: 100;
}
.skip-link:focus { top: 8px; }

/* 見出し・本文（サイト名やロゴは表示しない方針。ページは機能の見出しから始める） */
.hero { padding-top: 28px; padding-bottom: 8px; }
.hero h1 {
  margin: 0 0 6px;
  font-size: clamp(1.35rem, 1.1rem + 1.2vw, 1.9rem);
  line-height: 1.35;
}
.lead { margin: 0; color: var(--color-muted); font-size: 0.95rem; }

.content { padding-top: 32px; padding-bottom: 48px; }
.content section {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin-bottom: 16px;
}
.content h2 { margin: 0 0 12px; font-size: 1.25rem; line-height: 1.4; }
.content h3 { margin: 18px 0 4px; font-size: 1.02rem; }
.content p { margin: 0 0 8px; }
.content ul, .content ol { margin: 0; padding-left: 1.4em; }
.content li + li { margin-top: 6px; }

.faq details {
  border-top: 1px solid var(--color-border);
  padding: 10px 0;
}
.faq details:first-child { border-top: 0; padding-top: 0; }
.faq summary { cursor: pointer; font-weight: 600; }
.faq details p { margin: 8px 0 0; color: var(--color-muted); }

/* フッター */
.site-footer {
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-muted);
  font-size: 0.85rem;
  padding: 20px 0 28px;
}
.site-footer p { margin: 0 0 4px; }

/* ボタン */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 40px;
  padding: 8px 16px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  font: inherit;
  font-weight: 600;
  font-size: 0.95rem;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s, color 0.15s;
  -webkit-tap-highlight-color: transparent;
}
.btn:hover { border-color: #c4cad8; background: #f9fafc; }
.btn:focus-visible { outline: 3px solid rgba(79, 70, 229, 0.35); outline-offset: 2px; }
.btn:disabled, .btn[aria-disabled="true"] { opacity: 0.5; cursor: not-allowed; }
.btn[aria-pressed="true"] {
  background: var(--color-primary-soft);
  border-color: var(--color-primary);
  color: var(--color-primary);
}
.btn-primary {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}
.btn-primary:hover { background: var(--color-primary-hover); border-color: var(--color-primary-hover); }
.btn-primary:disabled:hover, .btn-primary[aria-disabled="true"]:hover { background: var(--color-primary); }
.btn-ghost { background: transparent; border-color: transparent; color: var(--color-primary); }
.btn-ghost:hover { background: var(--color-primary-soft); border-color: transparent; }
.btn-sm { min-height: 34px; padding: 6px 12px; font-size: 0.875rem; }
.btn-lg { min-height: 48px; padding: 12px 22px; font-size: 1rem; }
.btn-block { width: 100%; }

/* 404 など汎用ページ */
.simple-page { padding-top: 48px; padding-bottom: 64px; text-align: center; }