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CSS

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HTML 

              
                <link rel="stylesheet" href="https://unpkg.com/mvp.css" type="text/css">

<main>
  <p>Some colors need to be tweaked  in order to get nice visual results. Average chrome is around 0.2 and hue is incremented by values between 25 and 50.</p>
  <table class="color-table">
    <thead>
      <tr>
        <th></th>
        <th>50</th>
        <th>100</th>
        <th>200</th>
        <th>300</th>
        <th>400</th>
        <th>500</th>
        <th>600</th>
        <th>700</th>
        <th>800</th>
        <th>900</th>
      </tr>
    </thead>
    <tbody>
      <tr class="neutral">
        <th>neutral</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="gray">
        <th>gray</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="blue">
        <th>blue</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="indigo">
        <th>indigo</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="purple">
        <th>purple</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="pink">
        <th>pink</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="red">
        <th>red</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="orange">
        <th>orange</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="yellow">
        <th>yellow</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="green">
        <th>green</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="teal">
        <th>teal</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
      <tr class="cyan">
        <th>cyan</td>
        <td><button style="--l:95%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:90%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:80%;--color-btn:var(--color-text);"></button></td>
        <td><button style="--l:70%"></button></td>
        <td><button style="--l:60%"></button></td>
        <td><button style="--l:50%"></button></td>
        <td><button style="--l:40%"></button></td>
        <td><button style="--l:30%"></button></td>
        <td><button style="--l:20%"></button></td>
        <td><button style="--l:10%"></button></td>
      </tr>
    </tbody>
  </table>

  <hr>

  The APCA scoring system scores accessibility in levels out of 106 & -108. The higher the number, the higher the contrast. 15 is the minimum for non-text elements, while 75 is the preferred level for body text. Negative values means light text on dark background.
  <hr>
  <a href="https://caniuse.com/?search=oklch" target="blank">Browser support for OKLCH</a><br>
  <a href="https://caniuse.com/css-relative-colors" target="blank">Browser support for relative colors</a>
</main>
!

CSS 

              
                /* Syntax is oklch(L C H / a) */
:root {
  --color-text: #212529;
  --color-btn: #fff;
  --gray-c: 0.015;
  --gray-h: 248;
  --blue-c: 0.225;
  --blue-h: 250;
  --indigo-c: 0.3;
  --indigo-h: 275;
  --purple-c: 0.2;
  --purple-h: 320;
  --pink-c: 0.25;
  --pink-h: 0;
  --red-c: 0.25;
  --red-h: 25;
  --orange-c: 0.25;
  --orange-h: 50;
  --yellow-c: 0.18;
  --yellow-h: 85;
  --green-c: 0.2;
  --green-h: 140;
  --teal-c: 0.2;
  --teal-h: 160;
  --cyan-c: 0.2;
  --cyan-h: 210;
}

/*This works with relative colors
  /*--color:rgb(from var(--blue) h s l);*/

.color-table button {
  --lv: var(--l);
  --l: 50%;
  --c: 0;
  --h: 0;
  --a: 100%;
  --color: oklch(var(--lv) var(--c) var(--h) / var(--a));
  width: 50px;
  padding: 0.5em;
  background-color: var(--color);
  border-color: var(--color);
  color: var(--color-btn);
}

.color-table button:hover {
  filter: none;
  --a: 75%;
}

.neutral button {
  --c: 0;
}

.gray button {
  --c: var(--gray-c);
  --h: var(--gray-h);
}

.blue button {
  --c: var(--blue-c);
  --h: var(--blue-h);
}
.indigo button {
  --c: var(--indigo-c);
  --h: var(--indigo-h);
}
.purple button {
  --c: var(--purple-c);
  --h: var(--purple-h);
}
.pink button {
  --c: var(--pink-c);
  --h: var(--pink-h);
}
.red button {
  --c: var(--red-c);
  --h: var(--red-h);
}
.orange button {
  --c: var(--orange-c);
  --h: var(--orange-h);
}
.yellow button {
  --c: var(--yellow-c);
  --h: var(--yellow-h);
}
.green button {
  --c: var(--green-c);
  --h: var(--green-h);
}
.teal button {
  --c: var(--teal-c);
  --h: var(--teal-h);
}
.cyan button {
  --c: var(--cyan-c);
  --h: var(--cyan-h);
}
!

JS 

              
                import Color from "https://colorjs.io/dist/color.js";

document.querySelectorAll(".color-table button").forEach((btn) => {
  const styles = window.getComputedStyle(btn);
  const bg = styles.getPropertyValue("background-color");
  const color = styles.getPropertyValue("color");

  let text = new Color(color);
  let background = new Color(bg);
  let contrast = background.contrast(text, "APCA");

  if (contrast) {
    btn.innerHTML = contrast.toString().split(".")[0];
  }
});
!
999px

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