我的页脚在某些页面上只是粘性的

I'm building a web application in PHP. I want to include a footer which is sticky. I use include 'footer.php'; and it works perfect on all the pages except one page. On this page it sticks to the middle of the page with content under it. If I delete bottom: 0 it fixes it on this page but it's messed up on other pages.

CSS

#footer {
  background: #f7f7f7;
  position: absolute;
  border-top: 1px solid #dedede;
  height: 70px;
  width: 100%;
  bottom: 0;
  left: 0;
  overflow: hidden;
}

#footer li{
  padding-right: 20px;
  display: inline;
}

HTML

<!--Footer-->
<div id="footer">
    <span class="copyright">&copy; 2016 Gym</span>
    <ul class="social">
      <li><a href="#">About</a></li>
      <li><a href="#">Terms</a></li>
      <li><a href="#">Privacy</a></li>
      <li><a href="#">Contact</a></li>
      <li><a href="#">Blog</a></li>
    </ul>
    <div style="clear: both"></div>
</div>

I think you render footer where parent is relative.

You can also use position:fixed for sticky bottom of all pages.