nav {
  margin-bottom: 20px;
}

body {
  background: white;
  /* opacity: .5; */
  max-width: 550px;
  margin: 20px auto;
  padding: 20px;
  background-color: #222;
  color: #ddd;
  border-radius: 30px;
  /* text-align: center; */
}

h1,
h2 {
  text-align: center;
}

ul li {
  list-style-type: none;
  font-size: 18px;

}

a {
  color: lightblue;
}

a:visited {
  color: powderblue;
}

.flex {
  display: flex
}

img {
  margin: 20px 0;
}

.text-center {
  text-align: center;
}

p {
  margin: 10px 0;
}
.center {
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}