[id=change-box-sizing] {
  margin: 1em 0;
}
[id=change-box-sizing] p {
  -webkit-flex: 0 1 50%;
  -ms-flex: 0 1 50%;
  flex: 0 1 50%;
  width: 50%;
  padding: .5em 0;
}

.box-sizing-wrapper {
  background: #9e9e9e;
  margin: auto;
}
.box-sizing-wrapper article,
.box-sizing-wrapper aside {
  background: #FFEB3B;
  box-sizing: content-box;
  border: 10px solid #9C27B0;
  float: left;
  padding: 10px;
}
.box-sizing-wrapper::after {
  content: ' ';
  display: table;
  clear: both;
}
.box-sizing-wrapper p {
  margin: auto;
}

.primary {
  width: 60%;
}

.secondary {
  width: 40%;
}

[disabled] {
  opacity: .5;
}