How to get 'div' shaped as a flag with CSS

Question

I want to add a label on some of my elements on a website and design for a label that is a flag with an inverted V-shaped cut at the bottom.

So far I have this:

HTML

<div class="css-shapes"></div>

CSS

.css-shapes{
    border-left: 99px solid #f00fff;
    border-right: 99px solid #f00fff;
    border-bottom: 39px solid transparent;
}

http://jsfiddle.net/yhexkm4u/2/

However, I need the background to be white and border around this shape in purple and 1px. I was trying to fit the same shape just in white inside of this one, but everything got messy and didn't go as expected.

Maybe it is a wrong approach, but I want to end up with labels that would look something like this:

Answer 1

With CSS:

You can use CSS transforms on pseudo elements to create the background with a transparent inverted triangle at the bottom:

body{background:url('http://lorempixel.com/image_output/food-q-c-640-480-1.jpg');background-size:cover;}
p{
  position: relative;
  width: 150px; height: 150px;
  overflow: hidden;
  border-top:3px solid #EF0EFE;
}
p:before, p:after{
  content: '';
  position: absolute;
  top: -3px;
  height: 100%; width: 50%;
  z-index: -1;
  border:2px solid #EF0EFE;
  box-sizing:border-box;
}
p:before{
  left: 0;  
  transform-origin: 0 0;
  transform: skewY(-20deg);
  border-width:0 0 4px 3px;
}
p:after{
  right: 0;
  transform-origin: 100% 0;
  transform: skewY(20deg);
  border-width:0 3px 4px 0;
}

<p>Some text ... </p>

Note that you will need to add vendor prefixes on the transform and transform-origin properties to maximize browser support. See canIuse for more information.

---

With SVG

Another approach is to use an inline SVG with the polygon element:

body{background: url('http://lorempixel.com/image_output/food-q-c-640-480-1.jpg');background-size: cover;}
div{position: relative;width: 100px; height: 150px;}
svg{position: absolute;width: 100%;height: 100%;z-index: -1;}

<div>
  <svg viewbox="-1.5 -1.5 103 153">
    <polygon points="100 0, 100 100, 50 85, 0 100, 0 0" fill="transparent" stroke-width="3" stroke="#ef0efe"/>
  </svg>
  <p>Some text ... </p>
</div>

Answer 2

Here is a slightly different method using pseudo-elements and transform rotations to create an outlined banner like this:

• This angled shape is created with position: absolute pseudo-elements, :before and :after:

• The excess is cut off with overflow: hidden on the parent to form our banner:

• The outline is created with box-shadow and the two angles are prevented from overlapping by pulling / pushing the x-axis by 46px — box-shadow: 46px 0 0 3px #000

Full Example

div {
  height: 100px;
  width: 100px;
  margin: 100px auto;
  position: relative;
  overflow: hidden;
  border: solid 3px #000;
  border-bottom: none;
  text-align: center;
}
div:before,
div:after {
  content: '';
  display: block;
  height: 100%;
  width: 200%;
  transform: rotate(20deg);
  box-shadow: 46px 0 0 3px #000;
  position: absolute;
  top: 1px;
  right: -120%;
}
div:after {
  transform: rotate(-20deg);
  left: -120%;
  box-shadow: -46px 0 0 3px #000;
}

<div>Text</div>