qrcode.css

table, button, select, label, input[type="range"], input[type="text"] {
  width: 100%;
}

main {
  text-align: center;
  margin: auto;
}

#urilink {
  display: inline-block;
  margin: 0 auto 0.5em auto;
}

#qrcode {
  position: relative;
  max-width: 256px;
  display: block;
}

#preview {
  position: absolute;
  padding: calc(100% / 3);
  height: calc(100% / 3);
  width: calc(100% / 3);
  left: 0;
  top: 0;
}

#qrcode img:last-child {
  height: 100%;
  width: 100%;
}

#digits-display {
  text-align: left;
  width: 2em;
}

td {
  font-size: 0.9em;
}

td:last-of-type {
  width: 5.5em;
}

td:not(:first-of-type) {
  padding-left: 0.5em;
}

.shrink {
  width: 1%;
}

.left {
  text-align: left;
}

label {
  display: inline-block;
  white-space: nowrap;
}

input[type="text"] {
  border: 1px solid;
  height: 100%;
}

input[type="text"]:not(.error) {
  border-color: black;
}

input[type="text"].error {
  border-color: red;
}