index.css

@import url(https://fonts.googleapis.com/css?family=Open+Sans:700,300);

body {
  color: #444;
  font-size: 16px;
  font-weight: 300;
  line-height: 1em;
  text-align: center;
  background: #d0d0d0;
  font-family: "Open Sans", sans-serif;
}

h1 {
  font-weight: 300;
  font-size: 2.5em;
  margin: 2em 0 0.5em;
}

em,
strong {
  font: inherit;
  font-weight: 700;
}

article {
  width: 20em;
  margin: 0 auto;
}

p {
  line-height: 1.5em;
}

nav {
  display: flex;
  margin-bottom: 0;
  padding: 1em 0 2em;
  justify-content: center;
  border-bottom: 1px dotted rgba(68, 68, 68, 0.4);
}

nav .item {
  flex: 1;
  padding: 1em;
  font-size: 1em;
  margin: 0 0.2em;
  cursor: pointer;
  color: #0a4069;
  border-radius: 0;
  border-radius: 0.2em;
  box-sizing: border-box;
  background-color: transparent;
  transition: all 0.15s ease-in-out;
  font-family: "Open Sans", sans-serif;
  border: 1px solid rgba(254, 254, 254, 0.6);
}

nav .active {
  color: #76c900;
  border: 1px solid #031523;
  background-color: #0a4069;
}

.container {
  display: grid;
  grid-column-gap: 20px;
  transition: all 0.5s ease-in-out;
  grid-template-columns: 1fr 2fr 1fr;
}