This tutorial demonstrates creating a CSS3 paper curl effect without images. Previous tutorials showed how to create speech bubbles and ribbons using CSS3's :before and :after pseudo-elements; this builds on that technique.

A paper curl effect is an optical illusion, typically achieved with a shadow at the element's bottom. Previously, this required image editing software. CSS3 offers a superior alternative. The advantages of using CSS3 include: browser compatibility (it gracefully degrades in older browsers), background independence, scalability, reusable code, and easy customization.

First, create a simple HTML element:

<div class="box">My box</div>

Then, add basic inner and outer shading using box-shadow:

.box {
  position: relative;
  width: 500px;
  padding: 50px;
  margin: 0 auto;
  background-color: #fff;
  box-shadow: 0 0 5px rgba(0, 0, 0, 0.2), inset 0 0 50px rgba(0, 0, 0, 0.1);
}

The curl effect is created with two :before and :after pseudo-elements. These are:

1. Rotated and skewed using CSS3 transforms.
2. Positioned at the bottom edge.
3. Given a box-shadow.

Setting z-index: -1 places the pseudo-elements behind the main box, making only the shadow edges visible:

The CSS for the pseudo-elements:

.box:before, .box:after {
  position: absolute;
  width: 40%;
  height: 10px;
  content: ' ';
  left: 12px;
  bottom: 12px;
  background: transparent;
  transform: skew(-5deg) rotate(-5deg);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.3);
  z-index: -1;
}

.box:after {
  left: auto;
  right: 12px;
  transform: skew(5deg) rotate(5deg);
}

While this uses vendor prefixes for broader browser support, it remains more efficient than an image-based solution. The effect works in modern browsers; older browsers will simply omit the shadow. A demonstration page is available (link omitted as it's not provided in the input). The CSS is embedded within the HTML. IE6, 7, and 8 will gracefully degrade without showing the shadow effects.

Frequently Asked Questions (FAQs) about Pure CSS3 Paper Curls are omitted as they are already well-answered in the original text.

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