body {
    background: rgb(255, 255, 255);
    color: #fff;
    font-family: 'Oswald', sans-serif;
    font-size: 60px;
    font-weight: bold;
  }
  
  #container {
    /* 50px * 2 + 10px * 2 */
    margin: 16px auto;
  }
  
  #board {
    display: flex;
    flex-wrap: wrap;
    list-style: none;
    margin: 0 0 8px;
    padding: 20px;
    background: #fff;
    border-radius: 4px;
    border: 2px solid rgb(39, 39, 39);
  }

  .clr.true:before{
    content: 'クリア！';
    color: red;
}
  
#board li {
    background: #ffa551;
    width: 90px;
    height: 90px;
    margin: 5px;
    cursor: pointer;
    border-radius: 50%;
    line-height: 90px;
    text-align: center;
    box-shadow: 0 4px 0 #b87800;
}
  
#board li.pressed {
    background: #ccc;
    box-shadow: none;
    margin-top: 9px;
    margin-bottom: 1px;
}
  
#timer {
    font-family: 'Courier New', sans-serif;
    color:#000;
    margin-bottom: 8px;
    font-size: 40px;
    text-align: right;
}
  
#btn {
    cursor: pointer;
    user-select: none;
    background: #00aaff;
    padding: 8px;
    border-radius: 4px;
    font-size:60%;
    text-align: center;
    box-shadow: 0 4px 0 #0088cc;
}
  
#btn:active {
    margin-top: 12px;
    box-shadow: none;
}

#setsumei {
    font-size:35%;
    color:#111111;
    text-align: center;

}

.hidden_show {
    height: 0;
    padding: 0 px;
    overflow: hidden;
    opacity: 0;
    transition: 0.8s;
    position:absolute;
    color: #ff0000;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    -webkit-transform: translate(-50%, -50%);
    -ms-transform: translate(-50%, -50%);
}

#board .hidden_show2 {
  padding: 10px 0;
  height: auto;
  opacity: 1;
}

.upper{
  color:#666;
  position:fixed;
  right:50px;
  bottom:50px;
  transition:1s;
  opacity:0.7;
  border: 5px solid green;
  border-radius: 10px;
  font-size: 20px;
  padding :20px;
  font-weight: bold;

  }