.header{
 width:100%
}

.header img {
 width:100%;
}

.img-size{
 width:100%;
}

.nav{
 width:100%;
 height:auto;
 font-family:'メイリオ', 'Meiryo','ＭＳ ゴシック','Hiragino Kaku Gothic ProN','ヒラギノ角ゴ ProN W3',sans-serif;
 margin-right:auto;
 margin-left:auto;
 display:flex;
 justify-content:center; 
}

.nav ul li{
 list-style: none;
 padding:0px 0px 0px 0px;
 margin:10px 10px 10px 10px;
 float:left;
 font-family:'メイリオ', 'Meiryo','ＭＳ ゴシック','Hiragino Kaku Gothic ProN','ヒラギノ角ゴ ProN W3',sans-serif;
}


.container {
  width:75vw;
  margin-right:auto;
  margin-left:auto;
  display: flex;
  justify-content:center;
}

.main{
  font-family:'メイリオ', 'Meiryo','ＭＳ ゴシック','Hiragino Kaku Gothic ProN','ヒラギノ角ゴ ProN W3',sans-serif;
  width: 80%;
  padding: 10px;
}

.side-menu {
  font-family:'メイリオ', 'Meiryo','ＭＳ ゴシック','Hiragino Kaku Gothic ProN','ヒラギノ角ゴ ProN W3',sans-serif;
  width: 20%;
  padding: 10px;
}

.footer {
  text-align: center;
}

.footer p{
  text-align: center;
}

.dl {
    display: flex;
    justify-content: space-between;
    align-items: center;
}