body {
    font-family: Arial, sans-serif;
    line-height: 1.6;
    margin: 30px;
}
h1, h2, h3 {
    text-align: center;
}
.nav-list {
  list-style-type: none;
  margin: 0;
  padding: 0;
}
.content {
    max-width: 800px;
    margin: 0 auto;
}
.intro {
  width:70%

}
.nav {
  width:30%
}
.flex-container {
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
}