html {
  padding: 0px;
  font-family: "Be Vietnam Pro", sans-serif;
  background-color: whitesmoke;
  font-size: 18px;
}
body {
  font-family: Arial, Helvetica, sans-serif;
  margin: 0;
}

ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #333;
  position: fixed;
  top: 0;
  width: 100%;
}

li {
  float: left;
}

li a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

/* Change the link color to #111 (black) on hover */
li a:hover {
  background-color: #111;
}
.active {
  background-color: #04AA6D;
  color: white;
}

.content{
  padding: 20px 70px;
}

h1 {
  text-align: center;
  margin: 50px 0 0 0;
}

.center{
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 450px;
  height: 400px;
}

<img src= "number of northkorea missile tests and launches(rok presidency).png" style="width: 50px; height: 30px;">