> For the complete documentation index, see [llms.txt](https://a.b.cr/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://a.b.cr/textbook/frontend/a-react-ribbon-component.md).

# A React Ribbon Component

## Target

![](https://img.content.cc/a/2022/03/29/19-26-14-378-9bcd559be6672a46094b78041b3e8d37-bb5455.png)

## Code

```tsx
export default function Ribbon({
  width = 100,
  height = 20,
  text = "",
  color = "#4ade80",
}: {
  width?: number;
  height?: number;
  text?: string;
  color?: string;
}) {
  const sqrt2 = Math.sqrt(2);
  const tinyUnit = ((sqrt2 - 1) / 4) * width - (sqrt2 / 4) * height;
  const unitOffset = (1 / 2) * width + (sqrt2 / 2) * height + tinyUnit;
  const ribbonStyle = `
    .ribbonWrapper {
        position: absolute;
        right: 0;
        top: -${tinyUnit}px;
        right: -${tinyUnit}px;
        z-index: 10;
        width: ${width + tinyUnit}px;
        height: ${width + tinyUnit}px;
        overflow: hidden;
    }

    .ribbonWrapper::before {
        content: "";
        position: absolute;
        width: ${tinyUnit * 2}px;
        height: ${tinyUnit}px;
        right: ${unitOffset}px;
        border-top-left-radius: ${tinyUnit}px;
        background-color: ${color};
        background: -moz-linear-gradient(
          left,
          ${color} 1%,
          rgba(15, 51, 10, 1) 90%
        ); /* FF3.6+ */
        background: -webkit-gradient(
          linear,
          left top,
          right top,
          color-stop(1%, ${color}),
          color-stop(90%, rgba(15, 51, 10, 1))
        ); /* Chrome,Safari4+ */
        background: -webkit-linear-gradient(
          left,
          ${color} 1%,
          rgba(15, 51, 10, 1) 90%
        ); /* Chrome10+,Safari5.1+ */
        background: -o-linear-gradient(
          left,
          ${color} 1%,
          rgba(15, 51, 10, 1) 90%
        ); /* Opera 11.10+ */
        background: -ms-linear-gradient(
          left,
          ${color} 1%,ß
          rgba(15, 51, 10, 1) 90%
        ); /* IE10+ */
        background: linear-gradient(
          to right,
          ${color} 1%,
          rgba(15, 51, 10, 1) 90%
        ); /* W3C */
        filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#008a3b', endColorstr='#0f330a',GradientType=1 ); /* IE6-8 */
    }

    .ribbonWrapper::after {
        content: "";
        position: absolute;
        width: ${tinyUnit}px;
        height: ${tinyUnit * 2}px;
        top: ${unitOffset}px;
        right: 0px;
        border-bottom-right-radius: ${tinyUnit}px;
        background-color: #000;
        background: -moz-linear-gradient(
          top,
          rgba(15, 51, 10, 1) 10%,
          ${color} 99%
        ); /* FF3.6+ */
        background: -webkit-gradient(
          linear,
          left top,
          left bottom,
          color-stop(10%, rgba(15, 51, 10, 1)),
          color-stop(99%, ${color})
        ); /* Chrome,Safari4+ */
        background: -webkit-linear-gradient(
          top,
          rgba(15, 51, 10, 1) 10%,
          ${color} 99%
        ); /* Chrome10+,Safari5.1+ */
        background: -o-linear-gradient(
          top,
          rgba(15, 51, 10, 1) 10%,
          ${color} 99%
        ); /* Opera 11.10+ */
        background: -ms-linear-gradient(
          top,
          rgba(15, 51, 10, 1) 10%,
          ${color} 99%
        ); /* IE10+ */
        background: linear-gradient(
          to bottom,
          rgba(15, 51, 10, 1) 10%,
          ${color} 99%
        ); /* W3C */
        filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#0f330a', endColorstr='#008a3b',GradientType=0 ); /* IE6-8 */
    }

    .ribbonAnchor {
        position: absolute;
        bottom: 0;
        left: 0;
        width: ${width}px;
        height: ${width}px;
        #overflow: hidden;
    }

    .ribbon {
        position: relative;
        z-index: 10;
        top: ${width / 4 - height / 2}px;
        right: -${width / 4}px;
        --tw-rotate: 45deg;
        transform: var(--tw-transform);
        width: ${width}px;
        height: ${height}px;
        display: flex;
        justify-content: center;
        align-items: center;
        background-color: ${color};
    }
  `;
  return (
    <>
      <style>{ribbonStyle}</style>
      <div className="ribbonWrapper">
        <div className="ribbonAnchor">
          <div className="ribbon">
            <span className="text-sm text-white">{text}</span>
          </div>
        </div>
      </div>
    </>
  );
}
```

## Reference

The key to success is **AB**, LOL

The transition is moving the gray box to the red one, and the position of the **Center'** is at **a quarter to the top and a quarter to the right of the square**.

![](https://img.content.cc/a/2022/03/29/19-26-26-800-339269080ba1f7586be26b4513767ac1-dd53fb.png)

The following is the original version on paper:

![](https://img.content.cc/a/2022/03/29/19-26-43-334-b49f0145c6659ea506320277b979d39e-c0fe0c.png)

And idea from...

{% embed url="<https://codepen.io/CSS3fx/pen/AYwZjR>" %}


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