body {
    color: white;
    background-image: url('https://www.textures4photoshop.com/tex/thumbs/matrix-code-animation-gif-free-animated-background-716.gif');
}
h1 {
    font-size: 50px;
    font-family: Georgia, serif;
    color: #0d1b68;
    text-align: center;
}

h2 {
    font-size: 30px;
    font-family: Georgia, serif;
    color: #0d1b68;
    background: #000000;
}
a,p,li {
    font-size: 20px;
}

a {
    color: #0000ff;
    background: #000000;
}

.source {
    font-size: 10px;
    font-style: italic;
    text-align: center;
}

img {
    height: 300px;
    max-width: 70%;
}

.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
}
* {
  box-sizing: border-box;
}

.column {
  float: left;
  width: 33.33%;
  padding: 5px;
}
.row::after {
  content: "";
  clear: both;
  display: table;
}