How to prevent a DIV from expanding in width?

Question

How do I prevent a div from expanding in width?

I'd like .dont-expand to pretend that width: 100%; means "100%, but not counting myself". Basically, compute width: 100%; (ignoring itself), and setting that width in pixels width: Npx; -- in CSS and not JS.

.outer {
  position: absolute;
  border: 1px solid black;
}

/* This element sets the width of the container */
.has-width {
  width: 300px;
  margin-top: 10px;
  background: rgba(0,128,0,.2);
  border-right: 2px solid green;
  color: #888;
}

.dont-expand {
  /* width: ??? */
  
  /* This would be nice       */
  /* expand: false;           */
  
  /* Or this                  */
  /* width: toPx(100%);       */
  
  /* Or this                  */
  /* width: calc(100% + 0px); */
}

  <div class="outer">
    <div class="dont-expand">
      How do I get this text to wrap
      instead of growing the container?
    </div>
    <div class="has-width">
      I should be setting the width of "container".
    </div>
  </div>

jsbin link

Answer 1

It looks like you can make an element "appear" as 0 width to its parent, but still have it expand to the parent's width by doing: width: 0px; min-width: 100%.

This seems to be the cleanest, most browser-compatible solution. It also doesn't require changing the display property, which is a plus.

 /* Make it "shrink-to-fit", either inline-block, or position: absolute */
 .outer {
    /* position: absolute; */
    display: inline-block;
    border: 1px solid black;
  }

  /* This element sets the width of the container */
  .has-width {
    width: 300px;
    margin-top: 10px;
    background: rgba(0,128,0,.2);
    border-right: 2px solid green;
    color: #888;
  }

  /* Appears as 0 width to parent, but then expands to fit. */
  .dont-expand {
    width: 0px;
    min-width: 100%;
  }

<div class="outer">
  <div class="dont-expand">
    How do I get this text to wrap
    instead of growing the container?
  </div>
  <div class="has-width">
    I should be setting the width of "container".
  </div>
</div>

Answer 2

Try using

.outer {
  position: absolute;
  border: 1px solid black;
  width: min-content;
}

This should make it so that the width of the outer box becomes as small as possible, while not squashing content.