<style>
      * {
        font-family: "맑은 고딕", Arial, Helvetica, sans-serif;
        line-height: 150%;
      }
      body{
        margin-top: 20px;
        margin: 0 auto;
        max-width: 980px;
      }
      header, footer{
        height: 100px;
      }
      header h1 {
        display: inline;
      }
      footer{
        background-color: gray;
      }
      nav{
        height: 50px;
      }
      section{
        display: flex;
      }
      .content{
        flex:4;
      }
      aside{
        flex:1;
      }
      ul { list-style-type: none;}
      a {text-decoration: none;}
      nav ul li {
        display : inline;
        padding: 15px 30px;
        letter-spacing: 50x;
      }
      nav ul li:hover{
        background-color: #c0ca33;
      }
      nav ul {
        border-top: 2px solid  #c0ca33;
        border-bottom: 2px solid  #c0ca33;
        padding: 15px 20px;
        text-align: center;
      }
      .bigdata > img{
        padding-top: 50px;
        display: block;
        margin: 0 auto;
        width: 50%;
      }
      .action table{
        margin: 0 auto;
        width: 90%;
        font-size: 1.2em;
        border: 0px;
      }
      .action table th{
        background-color: #c0ca33;
      }
      video, iframe{
        margin: 0 auto;
        width: 70%;
      }
 </style>