<!DOCTYPE html>
<html lang="ja">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width,initial-scale=1" />
  <title>404 NotFound</title>
  <style>
    html, body {
      margin: 0;
      height: 100vh;
      display: flex;
      justify-content: center;
      align-items: center;
      color: var(--text-body);
      font-family: system-ui, -apple-system, Segoe UI, Roboto,
                   "Hiragino Kaku Gothic ProN", "Hiragino Sans",
                   "Noto Sans JP", Meiryo, sans-serif;
      background-color: #003A81;
    }
    .card {
      max-width: 600px;
      background: #ffffff;
      border: 1px solid rgba(148,163,184,0.3);
      border-radius: 16px;
      padding: 28px;
      text-align: center;
      box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    }
    .code {
      display: inline-block;
      font-weight: 700;
      font-size: 14px;
      letter-spacing: 0.08em;
      text-transform: uppercase;
      color: #ef4444;
      background: rgba(239,68,68,0.12);
      border: 1px solid rgba(239,68,68,0.35);
      padding: 8px 12px;
      border-radius: 999px;
    }
    h1 {
      margin: 16px 0 8px;
      font-size: 26px;
    }
    p { margin: 8px 0 0; color: var(--muted); }
 
    .btn-primary {
      appearance: none;
      width: 100%;
      height: 44px;
      border: none;
      border-radius: 8px;
      background: #003A81;
      color: #ffffff;
      font-size: 16px;
      font-weight: 600;
      letter-spacing: .02em;
      cursor: pointer;
      transition: transform .02s ease, opacity .15s ease, box-shadow .15s ease;
      box-shadow: 0 4px 12px rgba(0, 58, 129, 0.35);
    }
     .btn-primary {
       width: auto;
       min-width: 120px;
       padding: 10px 24px;
     }
    .btn-primary:hover { opacity: 0.95; }
    .btn-primary:active { transform: translateY(1px); }
  </style>
</head>
<body>
  <main class="card" role="main" aria-labelledby="title">
    <span class="code">HTTP 404 • Not Found</span>
    <h1 id="title">条件に一致するぺージがありませんでした。</h1>
    <p>お手数ですが、このタブを閉じてもう一度最初の画面から操作をやり直してください。</p>
    <br><br>
  </main>
</body>
</html>
