How to style radio buttons differently if they fit in a single row?

Question

PLAYGROUND HERE

I'd like to style radio buttons differently if they fit in a single row. For example:

The first container doesn't have enough space to fit all the radio buttons in a single row. Therefore, they appear vertically as normal radio buttons.

The second container has enough space. Therefore, the radio buttons appear as buttons.

Is that possible to achieve this behaviour using CSS only?

If not, Javascript "hack" is welcome.

PLAYGROUND HERE

---

HTML

<div class="container radio">
  <div>
    <input id="a1" type="radio" name="radio">
    <label for="a1">Yes,</label>
  </div>
  <div>
    <input id="a2" type="radio" name="radio">
    <label for="a2">it</label>
  </div>
  <div>
    <input id="a3" type="radio" name="radio">
    <label for="a3">is</label>
  </div>
  <div>
    <input id="a4" type="radio" name="radio">
    <label for="a4">possible</label>
  </div>
  <div>
    <input id="a5" type="radio" name="radio">
    <label for="a5">to</label>
  </div>
  <div>
    <input id="a6" type="radio" name="radio">
    <label for="a6">achieve</label>
  </div>
  <div>
    <input id="a7" type="radio" name="radio">
    <label for="a7">this</label>
  </div>
</div>
<div class="container buttons">
  <div>
    <input id="b1" type="radio" name="buttons">
    <label for="b1">Yes,</label>
  </div>
  <div>
    <input id="b2" type="radio" name="buttons">
    <label for="b2">it</label>
  </div>
  <div>
    <input id="b3" type="radio" name="buttons">
    <label for="b3">is</label>
  </div>
  <div>
    <input id="b4" type="radio" name="buttons">
    <label for="b4">possible</label>
  </div>
</div>

CSS (LESS)

.container {
  display: flex;
  width: 220px;
  padding: 20px;
  margin-top: 20px;
  border: 1px solid black;

  &.radio {
    flex-direction: column;
  }

  &.buttons {
    flex-direction: row;

    > div {
      input {
        display: none;

        &:checked + label {
          background-color: #ADFFFE;
        }
      }

      label {
        padding: 5px 10px;
        margin: 0 1px;
        background-color: #ccc;
      }
    }
  }
}

Answer 1

Not possible in CSS, but it doesn't take much JavaScript.

In CSS, add flex-shrink: 0 to > div. This will prevent .container's children from shrinking smaller than their extent.

In JavaScript:

1. Apply the buttons class.
2. Use Element.getBoundingClientRect to determine if the last child of .container is outside the extent of .container. If so, switch to the radio class. (You also need to take the right padding into account. Thanks to @Moob for pointing that out.)

Javascript

var container = document.querySelector('.container'),
    lastChild= document.querySelector('.container > :last-child'),
    paddingRight= parseInt(window.getComputedStyle(container, null).getPropertyValue('padding-right')),
    timer;

window.onresize = function() {
  clearTimeout(timer);
  timer= setTimeout(function() {
    container.classList.remove('radio');
    container.classList.add('buttons');
    if (container.getBoundingClientRect().right-paddingRight <
        lastChild.getBoundingClientRect().right) {
      container.classList.add('radio');
      container.classList.remove('buttons');
    }
  });
}

Updated JSBin