/* ===== 全体 ===== */
* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #0f172a;          /* ダーク背景 */
  color: #e5e7eb;
  min-height: 100vh;
}

/* ===== ヘッダー ===== */
header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 56px;
  background: #020617;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  z-index: 10;
}

main {
  padding-top: 72px; /* ヘッダー分 */
}

/* ===== カード ===== */
.card {
  background: #020617;
  margin: 16px;
  padding: 20px;
  border-radius: 18px;
}

/* ===== 数字・強調 ===== */
.big {
  font-size: 40px;
  font-weight: bold;
  margin: 12px 0;
}

/* ===== ボタン ===== */
button {
  width: 100%;
  margin-top: 12px;
  padding: 18px;
  font-size: 22px;
  border-radius: 16px;
  border: none;
  background: #2563eb;
  color: white;
}

button.secondary {
  background: #334155;
  font-size: 16px;
}

header .danger {
  margin-left: auto;          /* 右端へ */
  background: #7f1d1d;        /* 赤系 */
  color: #fee2e2;
}

header .danger:hover {
  background: #991b1b;
}

header {
  padding: 16px;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;

  margin-bottom: 16px; /* ★これが重要 */
}