#demo{
  font-size:48px;
  text-align:center;
}
button{
  font-size:48px;
  padding:5px;
  width:60px;
}


.history,
.ja{
  margin-top:10px;
  font-size:24px;
}

.word {
  margin: 20px auto;
  display: flex;
  justify-content: center;
  flex-wrap: nowrap;
  overflow-x: auto;
}

.word span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 36px;
  font-weight: bold;
  border: 1px solid #333;
  height: 60px;
  width: 60px;
  margin: 1px;
  box-sizing: border-box;
  white-space: nowrap; /* 改行禁止 */
  overflow: hidden;
  text-overflow: ellipsis;
}


.btns {
  display: grid;
  grid-template-columns: repeat(4, 1fr); /* 4列 */
  gap: 2px;
  justify-items: center;
  align-items: center;
  max-width: 300px; /* 必要に応じて調整 */
  margin: 20px auto;
}

.btns button {
  min-width: 64px;
  height: 60px;
  font-size: 24px;
  font-weight: bold;
  text-align: center;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  border: 2px solid #555;
  border-radius: 5px;
  background-color: #f0f0f0;
  cursor: pointer;
  flex-shrink: 0;
}