index.css

/*
  vertical/horiztonal centered fixed-width, flexible height box
  credit: https://stackoverflow.com/a/6182661

  masonry layout
  credit: https://w3bits.com/css-masonry/
*/

body, a {
  font-family: "Helvetica Neue";
}

body {
  background-color: #1c1c1c;
}

a, a:visited, a:hover, a:active {
  color: #0087ff;
  cursor: pointer;
  text-decoration: underline;
}

html {
  box-sizing: border-box;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

.outer {
  display: flex;
  align-items: center;
  justify-content: center;
}

.middle {
  display:        table-cell;
  vertical-align: top;
}

.inner {
  column-count: 2;
  column-gap: 1.5em;
  margin: 1.5em auto;
  width: 80%;
}

@media only screen and (min-width: 768px) {
  .inner {
    column-count: 3;
  }
}

@media only screen and (max-width: 500px) {
  .inner {
    column-count: 1;
  }
}

.box {
  background: #262626;
  border-radius: 5px;
  display: inline-block;
  font-size: 150%;
  margin: 0 0 1.5em;
  padding: 1em;
  width: 100%;
}

h3 {
  margin: 0;
  color: #8a8a8a
}