header {
    padding:10px;
    background: white;
  }
  
  #nav-drawer {
    position: relative;
  }
  
  /*チェックボックス等は非表示に*/
  .nav-unshown {
    display:none;
  }
  
  /*アイコンのスペース*/
  #nav-open {
    display: inline-block;
    max-width: 1366px;
    height: 22px;
    vertical-align: middle;
  }
  
  /*ハンバーガーの形をCSSで表現*/
  #nav-open span, #nav-open span:before, #nav-open span:after {
    position: absolute;
    height: 3px;/*線の太さ*/
    width: 25px;/*長さ*/
    border-radius: 3px;
    /* background: black; */
    background: #222222;
    display: block;
    content: '';
    cursor: pointer;
  }
  #nav-open span:before {
    bottom: -8px;
  }
  #nav-open span:after {
    bottom: -16px;
  }
  
  /*閉じる用の薄黒箇所*/
  #nav-close {
    display: none;
    position: fixed;
    z-index: 99;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #222222;
    opacity: 0;
    transition: .3s ease-in-out;
  }
  
  /*メニューの中身*/
  #nav-content {
    overflow: auto;
    position: fixed;
    top: 0;
    left: 0;
    z-index: 9999;
    width: 90%;
    max-width: 330px;/*最大幅（お好みで調整を）*/
    height: 100%;
    background: #222222;
    transition: .3s ease-in-out;
    -webkit-transform: translateX(-105%);
    transform: translateX(-105%);
  }
  #nav-content a {
    color: white;
    font-size: 20px;
  }
  
  /*チェックがついたら表示させる*/
  #nav-input:checked ~ #nav-close {
    display: block;
    opacity: .5;
  }
  
  #nav-input:checked ~ #nav-content {
    -webkit-transform: translateX(0%);
    transform: translateX(0%);
    box-shadow: 6px 0 25px rgba(0,0,0,.15);
  }