/* ====== 基本設定 ====== */
body {
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", sans-serif;
  margin: 0;
  padding: 0;
  background: linear-gradient(180deg, #f5f8ff 0%, #eaf0ff 100%);
  color: #333;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ====== ヘッダー（透明感あり） ====== */
header {
  position: relative;
  text-align: center;
  padding: 2.5rem 1rem 2rem;
  background: rgba(255, 255, 255, 0.35);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.3);
  box-shadow: 0 4px 18px rgba(0, 0, 0, 0.08);
  z-index: 100;
}

header h1 {
  margin-bottom: 0.4rem;
  font-size: 2rem;
  font-weight: 700;
  color: #007aff;
  letter-spacing: 0.5px;
}

header p {
  font-size: 0.95rem;
  opacity: 0.8;
  color: #444;
}

/* ====== メイン ====== */
main {
  flex: 1;
  max-width: 700px;
  margin: 2.5rem auto;
  padding: 0 1rem;
}

/* ====== カード ====== */
.card {
  background: rgba(255, 255, 255, 0.9);
  border-radius: 16px;
  padding: 1.6rem;
  margin-bottom: 1.5rem;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  width: 600px;   /* 固定 */
  max-width: 90%; /* 画面が狭いときは自動調整 */
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
}

.card h2 {
  margin-top: 0;
  color: #007aff;
  font-size: 1.3rem;
  margin-bottom: 0.8rem;
}

/* ====== リンク ====== */
a {
  color: #007aff;
  text-decoration: none;
  transition: 0.2s;
}

a:hover {
  text-decoration: underline;
}

/* ====== ボタン ====== */
.button {
  display: inline-block;
  background: linear-gradient(135deg, #007aff, #4aa8ff);
  color: white;
  padding: 0.6rem 1.4rem;
  border-radius: 10px;
  text-decoration: none;
  font-weight: 600;
  margin-top: 0.8rem;
  transition: background 0.2s, transform 0.15s;
}

.button:hover {
  background: linear-gradient(135deg, #0063d1, #3389ff);
  transform: translateY(-2px);
}

/* ====== フッター ====== */
footer {
  text-align: center;
  font-size: 0.85rem;
  padding: 1.5rem 0;
  color: #666;
  background: rgba(255, 255, 255, 0.5);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

/* ====== レスポンシブ対応 ====== */
@media (max-width: 600px) {
  header h1 {
    font-size: 1.6rem;
  }
  main {
    padding: 0 0.8rem;
  }
  .card {
    padding: 1.2rem;
  }
}