Make flex item be the width of its text

Question

I want to have a layout with two columns, where the left column is some kind of sidebar.

Now I want to use some text in the sidebar that shouldn't wrap.

When I do so it causes some kind of overflow and then using overflow:hidden hides a good part of the text.

How can I modify the left column to use the width of the unwrapped text and the right column to use the remaining space without dropping overflow:hidden?

#container {
    display: flex;
}
#sidebar {
    border: 1px solid red;
    flex 1 auto;
    overflow: hidden;
}
#sidebar .column {
    white-space: nowrap;
}
#sidebar .column span {
    margin: 2px;
    padding: 2px;
    border: 1px solid green;
    display: inline-block;
}
#content {
    border: 1px solid black;
    flex: 1 100%;
}

<div id="container">
    <div id="sidebar">
        <div class="column">
            <span>Howdy Cowboy, some text is missing here</span>
        </div>
    </div>
    <div id="content">
        Some funny content
    </div>
</div>

JSFIDDLE

Answer 1

How can I modify the left column to use the width of the unwrapped text and the right column to use the remaining space without dropping overflow:hidden?

Tell the left column to be only as wide as its content.

So instead of this:

#sidebar {
  flex: 1 auto;            /* 1 */
  overflow: hidden;
  border: 1px solid red;
}

Use this:

#sidebar {
  flex: 0 1 auto;        /* 1 */
  overflow: hidden;
  border: 1px solid red;
}

And tell the right column to consume any remaining space.

Instead of this:

#content {
  flex: 1 100%;         /* 2 */
  border: 1px solid black;
}

Use this:

#content {
  flex: 1;              /* 2 */
  border: 1px solid black;
}

revised fiddle

Notes:

1. flex: 1 auto is shorthand for flex-grow: 1 (defined), flex-shrink: 1 (by default) and flex-basis: auto (defined). Switch to flex-grow: 0 since you don't want the box to expand beyond the content.

   Incidentally, flex-grow: 0, flex-shrink: 1 and flex-basis: auto are all default values. Hence, you can omit the flex rule and get the same result.

   Note that your code won't work in any case because you have a syntax error (a missing :).

2. flex-basis: 100% will force the item to expand as much as it can across the width of the container, even intruding into the sidebar space if it can. Just use flex: 1 (same as flex-grow: 1, flex-shrink: 1, flex-basis: 0), which tells the item to consume only free space.