:root {
  --color-background: #1c1f26;
  --color-text: white;
}

body {
  background-color: var(--color-background);
  font-family: "Noto Sans", "Helvetica Neue", Helvetica, sans-serif;
  margin: 0;
}

header {
  height: 10vh;
}

h1 {
  color: var(--color-text);
  text-align: center;
  line-height: 10vh;
  margin: 0;
}

main {
  display: grid;
  grid-template-rows: 1fr 1fr;
  grid-template-columns: 1fr 1fr;
  height: 36vh;
  margin: 2vh 20vw;
}

@media only screen and (max-width: 1200px) {
  main {
    margin: 2vh 10vw;
  }
}

@media only screen and (max-width: 900px) {
  main {
    grid-template-rows: repeat(1fr);
    grid-template-columns: 1fr;
    height: 72vh;
  }
}

@media only screen and (max-width: 600px) {
  main {
    margin: 2vh 5vw;
  }
}

.reference {
  border-radius: 1em;
  box-sizing: border-box;
  color: var(--color-text);
  height: 18vh;
  padding: 4vh 0;
  text-align: center;
  text-decoration: none;
  transition: background-color 100ms ease;
  vertical-align: middle;
}

.reference > img {
  height: 10vh;
  width: 10vh;
  margin-right: 1em;
  vertical-align: middle;
}

.reference > h2 {
  display: inline;
  margin: 0;
  text-decoration: underline;
}

.reference:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

#logo {
  display: block;
  height: 50vh;
  margin: 0 auto;
}