html,
body {
  height: 100%;
  margin: 0;
}

body {
  align-items: center;
  display: flex;
  justify-content: center;
  color: rgba(0, 0, 0, 0.7);
  background: linear-gradient(to bottom right, #00d034, #c0c0c0);
  font-size: 1.5rem;
  font-family: sans-serif;
}

main {
  width: 30em;
}

.entry,
.readout {
  margin: 0 auto;
  padding: 8px;
  border: 1px solid black;
  background-color: rgba(0, 0, 0, 0.25);
}

.entry input {
  font-size: 1.5rem;
  background: transparent;
  border: 1px solid rgba(0, 0, 0, 0.6);
  width: 100%;
  display: block;
  box-sizing: border-box;
  margin-top: 16px;
}

.readout {
  margin-top: 16px;
}

input:focus {
  outline: 0;
  border-color: #550096;
}

.footnote {
  font-size: 0.9rem;
  margin-top: 16px;
}