bootstrap_callout

.bs-callout {
  margin: 20px 0;
  padding: 15px 30px 15px 15px;
  border-left: 5px solid #eee;
}

.bs-callout-danger {
  background-color: #fcf2f2;
  border-color: #dFb5b4;
}

.bs-callout-warning {
  background-color: #fefbed;
  border-color: #f1e7bc;
}

index.html

<div class="bs-callout bs-callout-danger">
  <h4>Cross-browser compatibility</h4>
  <p>Striped tables are styled via the <code>:nth-child</code> CSS selector, which is not available in Internet Explorer 8.</p>
</div>

<div class="bs-callout bs-callout-warning">
  <h4>Link functionality of <code>&lt;a&gt;</code> not impacted</h4>
  <p>This class will only change the appearance of <code>&lt;a class="btn btn-default"&gt;</code> buttons, not their functionality. Use custom JavaScript to disable links here.</p>
</div>