header {
  display: flex;
  justify-content: center;
  padding: 20px;
}
table {
  margin: 0 auto;
  border-spacing: 15px;
}
td {
  margin: 100px;
}
header button {
 font-size: 1em;
  padding: 10px;
}
html {
  font-family: Avenir, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  /* text-align: center; */
  color: #2c3e50;
  font-size: 2em;
  /* margin-top: 60px; */
}