body {
    font-family: helvetica, sans-serif;
    padding-bottom: 100px;
  }
  
  header {
    background: url(//qiita-image-store.s3.amazonaws.com/0/48396/4ac222d9-6a3b-c09f-25a3-cff918dd2c69.jpeg ) no-repeat center center;
    background-size: cover;
    padding: 24% 0;
    color: #fff;
    text-align: center;
  }
  
  h1 {
    font-size: 48px;
    letter-spacing: .15em;
    font-family: helvetica;
    margin-bottom: 5px;
  }
  
  .menu-open-btn {
    background: url(//qiita-image-store.s3.amazonaws.com/0/48396/56dc0274-0ec5-d10e-16d1-35209ffe0154.png) no-repeat center center;
    width: 50px;
    height: 50px;
    background-size: 25px;
    position: fixed;
    top: 10px;
    right: 10px;
  }
  
  #content {
    text-align: center;
  }
  
  main {
    margin: 0 auto;
    padding: 30px 25px;
    max-width: 800px;
    text-align: left;
    line-height: 1.4;
  }
  
  main h2 {
    font-size: 24px;
    font-weight: bold;
    padding: 1em 0 .5em;
  }
  
  main p {
    margin: .5em 0;
  }
  
  #modal-menu {
    position: fixed;
    width: 100%;
    height: 100%;
    background-color: rgba(50, 47, 45, 0.9);
    top: 0;
    left: 0;
    opacity: 0;
    transition: opacity .2s ease-out;
    pointer-events: none;
  }
  
  .menu-nav {
    margin-top: 100px;
    text-align: center;
    position: relative;
    transform: translateY(50px);
    transition: all .2s ease-out;
  }
  
  .menu-nav a {
    color: #fff;
    text-decoration: none;
    font-size: 40px;
    margin: 20px 0;
    display: block;
  }
  
  .menu-nav a:hover {
    text-decoration: underline;
  }
  
  .menu-close-btn {
    background: url(//qiita-image-store.s3.amazonaws.com/0/48396/c90e1498-4813-cf79-8bc3-118456431bc5.png) no-repeat center center;
    width: 50px;
    height: 50px;
    background-size: 30px;
    position: absolute;
    top: 10px;
    right: 10px;
  }
  
  body.is-menu-open #modal-menu {
    opacity: 1;
    pointer-events: auto;
  }
  
  body.is-menu-open #content {
    pointer-events: none;
    transition: all .2s ease-out;
    -webkit-filter: blur(8px);
       -moz-filter: blur(8px);
        -ms-filter: blur(8px);
            filter: blur(8px);
  }
  
  body.is-menu-open .menu-nav {
    transform: translateY(0);
  }