--description--

An element's margin controls the amount of space between an element's border and surrounding elements.

If you set an element's margin to a negative value, the element will grow larger.

--instructions--

Try to set the margin to a negative value like the one for the red box.

Change the margin of the blue box to -15px, so it fills the entire horizontal width of the yellow box around it.

--hints--

Your blue-box class should give elements -15px of margin.

assert($('.blue-box').css('margin-top') === '-15px');

--seed--

--seed-contents--

<style>
  .injected-text {
    margin-bottom: -25px;
    text-align: center;
  }

  .box {
    border-style: solid;
    border-color: black;
    border-width: 5px;
    text-align: center;
  }

  .yellow-box {
    background-color: yellow;
    padding: 10px;
  }

  .red-box {
    background-color: crimson;
    color: #fff;
    padding: 20px;
    margin: -15px;
  }

  .blue-box {
    background-color: blue;
    color: #fff;
    padding: 20px;
    margin: 20px;
  }
</style>

<div class="box yellow-box">
  <h5 class="box red-box">padding</h5>
  <h5 class="box blue-box">padding</h5>
</div>

--solutions--

<style>
  .injected-text {
    margin-bottom: -25px;
    text-align: center;
  }

  .box {
    border-style: solid;
    border-color: black;
    border-width: 5px;
    text-align: center;
  }

  .yellow-box {
    background-color: yellow;
    padding: 10px;
  }

  .red-box {
    background-color: crimson;
    color: #fff;
    padding: 20px;
    margin: -15px;
  }

  .blue-box {
    background-color: blue;
    color: #fff;
    padding: 20px;
    margin: 20px;
    margin-top: -15px;
  }
</style>

<div class="box yellow-box">
  <h5 class="box red-box">padding</h5>
  <h5 class="box blue-box">padding</h5>
</div>