style.css

@import url(http://fonts.googleapis.com/css?family=Noto+Sans);
body {
  font-family: 'Noto Sans', sans-serif;
  margin: 0;
}
a {
  color: steelblue;
  text-decoration: none;
}
.logo {
  margin: 0;
  text-align: center;
}
.logo a {
  display: inline-block;
  margin: 0;
  padding: 20px;
}
.nav {
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: row;
}
.nav li {
  flex: 1;
  list-style: none;
}
.nav a {
  background: #000;
  color: #fff;
  display: block;
  padding: 20px 10px;
  text-align: center;
  text-decoration: none;
  -webkit-transition: .3s;
  -o-transition: .3s;
  transition: .3s;
}
.nav a:hover {
  background: steelblue;
}
.content {
  min-height: 220px;
  max-width: 1000px;
  margin: 100px auto;
}
.footer {
  background: #000;
  color: #fff;
  padding: 20px;
  text-align: center;
}
@media (max-width: 768px) {
  body {
    margin-bottom: 80px;
    word-wrap: break-word;
  }
  .header {
    background: #000;
  }
  .nav {
    bottom: 0;
    position: fixed;
    width: 100%;
  }
  .nav li:nth-child(n+1) a {
    background: blue;
  }
  .nav li:nth-child(n+2) a {
    background: cyan;
  }
  .nav li:nth-child(n+3) a {
    background: red;
  }
  .nav li:nth-child(n+4) a {
    background: green;
  }
  .nav li:nth-child(n+5) a {
    background: gold;
  }
  .nav li a:hover {
    background: steelblue;
  }
  .content {
    margin: 20px;
  }
  .footer {
    display: none;
  }
}