h1 { font-family: Arial, Helvetica, sans-serif; }

/* 数値入力欄のスピンボタン（上下矢印）を完全に非表示 */
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
  -webkit-appearance: none !important;
  appearance: none !important;
  margin: 0 !important;
}

input[type="number"] {
  -moz-appearance: textfield !important;
  appearance: textfield !important;
}