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                .color-list__item {
  margin: 0.25rem; /* We need to know the margin size in the JS file */

color-list.css hosted with ❤ by GitHub
.color-swatch {
  width: 10rem; /* We need to know this width in the JS file */


 * Determines how many items can fit on one line, 
 * given the line width and item width.
const getMaxItemsPerLine = (lineWidth, itemSize) =>
  Math.floor(lineWidth / itemSize);

 * Determines if the item should be hidden, given
 * the items index and the max number of items allowed
 * on one line.
const isItemHidden = (maxItemsPerLine, itemIndex) =>
  itemIndex > maxItemsPerLine - 1;

export const ColorList = ({ colorSwatches, handleClick }) => {
  const [listWidth, setListWidth] = React.useState(-1);
  // Here are the values from our CSS files
  const colorSwatchSize = 160; // px, equivalent to the 10rem width assuming our root font-size is 16px
  const listItemMargin = 4; // px, equivalent to the 0.25rem width assuming our root font-size is 16px
  const colorSwatchTotalWidth = colorSwatchSize + 2 * listItemMargin;
  const maxItemsPerLine = getMaxItemsPerLine(listWidth, colorSwatchTotalWidth);

  return (
    <div className="color-list__container">
        onResize={contentRect => setListWidth(contentRect.bounds.width)}
        {({ measureRef }) => (
          <ul ref={measureRef} className="color-list">
            {, i) => {
              const hidden = isItemHidden(maxItemsPerLine, i); {/* Item will be hidden if doesn't fit on the first line */}
              return (
                <li key={i} className="color-list__item" hidden={hidden}>