* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: Helvetica, Arial, sans-serif;
  font-size: 18px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow: hidden;
}
#app {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  height: 100vh;
}
#app > *:not(:last-child) {
  margin-bottom: 20px;
}