Guess CSS!

0 : 0

CSS A
/* Only text in bold differs */
body {
  display: flex;
  flex-direction: column-reverse;
  justify-content: space-around;
  align-items: center;
}
html, body {
  height: 100%;
  margin: 0;
}
div {
  border: 1px solid #000;
  padding: .5em;
}
body {
  color: #000;
  font-family: Menlo,
    "Ubuntu Mono", Consolas,
    source-code-pro, monospace;
  font-size: 13px;
}
CSS B
/* Only text in bold differs */
body {
  display: flex;
  flex-direction: column-reverse;
  justify-content: center;
  align-items: flex-end;
}
html, body {
  height: 100%;
  margin: 0;
}
div {
  border: 1px solid #000;
  padding: .5em;
}
body {
  color: #000;
  font-family: Menlo,
    "Ubuntu Mono", Consolas,
    source-code-pro, monospace;
  font-size: 13px;
}
CSS C
/* Only text in bold differs */
body {
  display: flex;
  flex-direction: column-reverse;
  justify-content: space-between;
  align-items: stretch;
}
html, body {
  height: 100%;
  margin: 0;
}
div {
  border: 1px solid #000;
  padding: .5em;
}
body {
  color: #000;
  font-family: Menlo,
    "Ubuntu Mono", Consolas,
    source-code-pro, monospace;
  font-size: 13px;
}
<body>
  <div class="a">a</div>
  <div class="b">b</div>
</body>