main.css

body {
  padding:0;
  margin:0;
}

img {
  max-width: 100%;
}

section {
  width: 100%;
  height: 100vh;
  min-height: 100vh;
  display: table;
  font-weight: lighter;
  font-size: 60px;
  font-family: avenir next, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  text-align: center;
}

code {
  font-family: "Envy Code R", "Courier New", Courier, monospace;
}

a {
  text-decoration: none;
  color: #333;
}

input {
  font-family: avenir next, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  font-size: 40px;
  font-weight: 300;
}

.align-middle {
  display: table-cell;
  vertical-align: middle;
}

.white {
  color: white;
}

.text-shadow-dark {
  text-shadow: 1px 1px #333;
}

.red-cross {
  display: inline-block;
  position: relative;
  width: 260px;
  height: 260px;
  margin: 20px;
}
.red-cross::before,
.red-cross::after {
  content: '';
  display: block;
  background: red;
  position: absolute;
}
.red-cross::before {
  width: 80px;
  height: 260px;
  left: 90px;
}
.red-cross::after {
  width: 260px;
  height: 80px;
  top: 90px;
}

.tableflip {
  display: inline-block;
  width: 60px;
  height: 70px;
  background: url(https://tableflip.io/img/tableflip.min.svg) no-repeat;
  background-size: 100% auto;
  font-size:0;
  user-select: none;
  opacity: 0.8;
  transition: opacity 400ms;
}
.tableflip:hover {
  opacity: 1;
}