Paragraph does not wrap with div

Question

I am puzzled by a wrap that works 90% of the time - but breaks in specific word compositions.

It's based on the css-tricks "Don't overthink it grids" blog post, so it seems the problem already existed there at the end of the tutorial.

Live/Demo/Code: http://codepen.io/anon/pen/xdFhr

As you can see the following paragraph:

BIDFIK roolbool rackorack op deenoopaloomba ka jandalop me pep google lopski perfect preference group call later go take foot pep universal.

Flows out of the parent div. Why?

<h1>Don't Overthink It Grids <em>(while we wait for flexbox!)</em></h1>

<div class="grid">
  <div class="col-2-3">
    <div class="module">
      <h3>2/3</h3>
      <p>BIDFIK roolbool rackorack op deenoopaloomba ka jandalop me pep google lopski perfect preference group call later go take foot pep universal.</p>
    </div>
  </div>
  <div class="col-1-3">
    <div class="module">
      <h3>1/3</h3>
      <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies</p>
    </div>
  </div>
</div>

<div class="grid grid-pad">
  <div class="col-2-3">
    <div class="module">
      <h3>2/3 (Opt-in Outside Padding)</h3>
      <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>
    </div>
  </div>
  <div class="col-1-3">
    <div class="module">
      <h3>1/3</h3>
      <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam.</p>
    </div>
  </div>
</div>

<div class="grid grid-pad">
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
  <div class="col-1-8">
    <div class="module">
      <h3>1/8</h3>
    </div>
  </div>
</div>

<div class="grid grid-pad">
  <div class="col-1-4">
    <div class="module">
      <h3>1/4</h3>
    </div>
  </div>
  <div class="col-1-2">
    <div class="module">
      <h3>1/2</h3>
    </div>
  </div>
  <div class="col-1-4">
    <div class="module">
      <h3>1/4</h3>
    </div>
  </div>
</div>

CSS:

* {
  @include box-sizing(border-box);
}

$pad: 20px;

.grid {
  background: white;
  margin: 0 0 $pad 0;

  &:after {
    /* Or @extend clearfix */
    content: "";
    display: table;
    clear: both;
  }
}

[class*='col-'] {
    float: left;
  padding-right: $pad;
  .grid &:last-of-type {
    padding-right: 0;
  }
}
.col-2-3 {
    width: 66.66%;
}
.col-1-3 {
    width: 33.33%;
}
.col-1-2 {
    width: 50%;
}
.col-1-4 {
    width: 25%;
}
.col-1-8 {
    width: 12.5%;
}

.module {
  padding: $pad;
  background: #eee;
}

/* Opt-in outside padding */
.grid-pad {
  padding: $pad 0 $pad $pad;
  [class*='col-']:last-of-type {
    padding-right: $pad;
  }
}

body {
    padding: 10px 50px 200px;
  background: url(http://s.cdpn.io/3/dark_wall_@2X.png);
  background-size: 300px 300px;
}
h1 {
  color: white;
  em {
    color: #666;
    font-size: 16px;
  }
}

Answer 1

It was invisible chars/hidden characters.

I removed it with a Vim command:

:%s/\%xa0/ /gc

Where xa0 is the hex code of the char (0xA0).