csspseudo-class

How to position a CSS triangle using ::after?

I've created a div with a bottom arrow using ::after. Here is the HTML code:

.sidebar-resources-categories {
  height: 50px;
  margin-bottom: 20px;
  background-color: #e8e8e8;
  font-weight: 600;
  line-height: 50px;
  text-align: center;
  font-size: 20px;
}

.sidebar-resources-categories::after {
  content: '';
  position: absolute;
  left: 42%;
  top: 100%;
  width: 0;
  height: 0;
  border-left: 20px solid transparent;
  border-right: 20px solid transparent;
  border-top: 20px solid #e8e8e8;
  clear: both;
}
<div class="sidebar-resources-categories">Topics</div>
<div class="text-content">ok ok</div>

<div class="sidebar-resources-categories">Topics</div>
<div class="text-content">ok ok</div>

And here is the CSS:

.sidebar-resources-categories{
    height: 50px;
    margin-bottom: 20px;
    background-color: #e8e8e8;
    font-weight: 600;
    line-height: 50px;
    text-align: center;
    font-size: 20px;
}
.sidebar-resources-categories::after{
    content: '';
    position: absolute;
    left: 42%;
    top: 100%;
    width: 0;
    height: 0;
    border-left: 20px solid transparent;
    border-right: 20px solid transparent;
    border-top: 20px solid #e8e8e8;
    clear: both;
}

Here is the result:

Here is the result

I would like the arrow to be at the very bottom of the grey div. I don't want to have the content between the div and the bottom arrow. Do you know how I can do that?

Solution

  • Just add position:relative to the parent element .sidebar-resources-categories

    http://jsfiddle.net/matthewabrman/5msuY/

    explanation: the ::after elements position is based off of it's parent, in your example you probably had a parent element of the .sidebar-res... which had a set height, therefore it rendered just below it. Adding position relative to the .sidebar-res... makes the after elements move to 100% of it's parent which now becomes the .sidebar-res... because it's position is set to relative. I'm not sure how to explain it but it's expected behaviour.

    read more on the subject: http://css-tricks.com/absolute-positioning-inside-relative-positioning/