style.css

body,
select {
  font-family: 'Open Sans', sans-serif;
  margin: 0;
}

/* https://www.paulirish.com/2012/box-sizing-border-box-ftw/ */
html {
  box-sizing: border-box;
  font-size: 62.5%;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

.all-box,
select {
  width: 100%;
}

select {
  position: fixed;
  z-index: 3;
}
.all-box {
  margin: 0 auto;
  padding-top: 2.25rem;
  display: flex;
  flex-flow: row wrap;
  justify-content: start;
}
.json-box {
  position: absolute;
  top: 2.25rem;
  z-index: 2;
}
.box-color {
  text-align: center;
  flex-grow: 1;
  padding: 5px;
  cursor: crosshair;
  border-right: 1px dashed black;
  border-bottom: 1px dashed black;
  transition-property: font-size;
  transition-duration: .8s;
}

.box-color,
select,
.json-box {
  font-size: 1.5rem;
}

.box-color:hover {
  flex-basis: 22%;
  font-size: 2.25rem;
}

span {
  display: block;
}

.none {
  display: none;
}