Creating a Responsive 45-Degree Ribbon with Folded Corner

Is it possible to have a CSS ribbon shaped like a corner?

Using a PNG image is one option, but it's not ideal for responsiveness. Here's how to create it purely with CSS:

.container {
  width: 200px;
  height: 150px;
  position: relative;
  display: inline-block;
  margin: 10px;
  background: lightblue;
}

.stack-top {
  --d: 5px;
  --g: 16px;
  --c: #333;

  position: absolute;
  top: 0;
  right: 0;
  transform: translate(29.29%, -100%) rotate(45deg);
  color: #fff;
  text-align: center;
  width: 100px;
  transform-origin: bottom left;
  padding: 5px 0 calc(var(--d)   5px);
  background:
    linear-gradient(135deg, transparent var(--g), var(--c) calc(var(--g) - 0.3px)) left,
    linear-gradient(-135deg, transparent var(--g), var(--c) calc(var(--g) - 0.3px)) right;
  background-size: 51% 100%;
  background-repeat: no-repeat;
  clip-path: polygon(
    0 0,
    100% 0,
    100% 100%,
    calc(100% - var(--d)) calc(100% - var(--d)),
    var(--d) calc(100% - var(--d)),
    0 100%
  );
}

Customizing the Ribbon

You can adjust the following variables to customize the ribbon's appearance:

• --d: Controls the size of the corner fold
• --g: Controls the height of the ribbon's peak
• --c: Specifies the color of the ribbon

Usage

To use the ribbon, simply add the following HTML code to your document:

  
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You can also specify the custom variables directly in the HTML by using the style attribute, as seen in the updated example below:

  
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