body {
  display: flex;
  flex-flow: row nowrap;
  justify-content: space-around;
}

main {
  max-width: 800px;
  padding: 5px;

  display: flex;
  flex-flow: column nowrap;
  align-items: center;
}

main > * {
  margin: 5px;
}

#ex_ans {
  margin-top: 10px;

  display: flex;
  flex-flow: row wrap;
  justify-content: space-around;
}

#ex_ans > * {
  margin: 5px;
  width: 45%;
}

button {
  font-size: large;
}

#ex_next {
  width: 200px;
}

#ex_scorediv {
  font-size: large;
}

#footer {
  position: absolute;
  bottom: 0;

  font-size: small;

  display: flex;
  flex-flow: row wrap;
  justify-content: space-around;
}

#footer > * {
  margin: 5px;
}