Child elements expanding outside parent element with flex

Question

I have used CSS flex to display two divs side by side which are contained inside a wrapper and I have been trying so that inside #myClippetWrapper is where I set the height, so in the child elements of #myClippetWrapper I can just set height: 100%;.

But as you can see from running the snippet below all of the elements inside #myClippetWrapper go outside of the main section, they are all hanging out of the main content div?

I don't want to use overflow: auto because I do not want a scroll bar there, I just need the child elements of #myClippetWrapper to not be outside of the main section/ div.

main {
  margin: 0 auto;
  margin-top: 10px;
  margin-bottom: 10px;
  padding: 8px;
  background-color: red;
  width: 100%;
  max-width: 50%;
  height: auto;
}

#myClippetWrapper {
  display: flex;
  height: 700px;
}

#clippetNav {
  padding: 10px;
  width: 250px;
  height: 100%;
  background-color: #222222;
  margin-right: 10px;
}

#codeAndNotesWrapper {
  display: flex;
  width: 100%;
}

#codeAndNotesWrapper>div {
  flex-basis: 100%;
  height: 100%;
}

#codeView {
  padding: 10px;
  /*flex: 0 0 40%;*/
  height: 100%;
  background-color: #222222;
  margin-right: 10px;
}

#noteView {
  padding: 10px;
  /*flex: 1;*/
  height: 100%;
  background-color: #222222;
}

#codeNotesEditor {
  height: 100%;
  background-color: #EAEAEA;
}

<main>
  <div id="myClippetWrapper">

    <div id="clippetNav">

    </div>

    <div id="codeAndNotesWrapper">

      <div id="codeView">

      </div>

      <div id="noteView">

        <div id="codeNotesEditor">

        </div>

      </div>

    </div>

  </div>
</main>

Answer 1

In many cases, flexbox eliminates the need to use percentage heights.

An initial setting of a flex container is align-items: stretch. This means that in flex-direction: row (like in your code) flex items will automatically expand the full height of the container.

Alternatively, you can use flex-direction: column and then apply flex: 1 to the children, which can also make a flex item expand the full height of the parent.

main {
  max-width: 50%;
  margin: 10px auto;
  padding: 8px;
  background-color: red;
}

#myClippetWrapper {
  display: flex;
  height: 700px;
}

#clippetNav {
  display: flex;
  padding: 10px;
  width: 250px;
  margin-right: 10px;
  background-color: #222222;
}

#codeAndNotesWrapper {
  display: flex;
  width: 100%;
}

#codeAndNotesWrapper>div {
  display: flex;
  flex-basis: 100%;
}

#codeView {
  display: flex;
  padding: 10px;
  margin-right: 10px;
  background-color: #222222;
}

#noteView {
  display: flex;
  flex-direction: column;
  padding: 10px;
  background-color: #222222;
}

#codeNotesEditor {
  flex: 1;
  background-color: #EAEAEA;
}

<main>
  <div id="myClippetWrapper">
    <div id="clippetNav"></div>
    <div id="codeAndNotesWrapper">
      <div id="codeView"></div>
      <div id="noteView">
        <div id="codeNotesEditor"></div>
      </div>
    </div>
  </div>
</main>

jsFiddle

Answer 2

Add

 box-sizing: border-box;

To your child elements. This will make the padding show on the inside of the box rather than the outside and will not increase the overall size.