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                <div class="container">
  <h1 class="h1">Moby Dick</h1>
  <p>Herman Melville</p>
  <p id="font-size-gauge"></p>
  <p class="p">
    <span class="first-line">Call me Ishmael.</span> Some years ago—never
    mind how long precisely—having little or no money in my purse, and
    nothing particular to interest me on shore, I thought I would sail about
    a little and see the watery part of the world. It is a way I have of
    driving off the spleen, and regulating the circulation. Whenever I find
    myself growing grim about the mouth; whenever it is a damp, drizzly
    November in my soul; whenever I find myself involuntarily pausing before
    coffin warehouses, and bringing up the rear of every funeral I meet; and
    especially whenever my hypos get such an upper hand of me, that it
    requires a strong moral principle to prevent me from deliberately
    stepping into the street, and methodically knocking people's hats
    off—then, I account it high time to get to sea as soon as I can. This is
    my substitute for pistol and ball. With a philosophical flourish Cato
    throws himself upon his sword; I quietly take to the ship. There is
    nothing surprising in this. If they but knew it, almost all men in their
    degree, some time or other, cherish very nearly the same feelings
    towards the ocean with me.
    There now is your insular city of the Manhattoes, belted round by
    wharves as Indian isles by coral reefs—commerce surrounds it with her
    surf. Right and left, the streets take you waterward. Its extreme
    down-town is the battery, where that noble mole is washed by waves, and
    cooled by breezes, which a few hours previous were out of sight of land.
    Look at the crowds of water-gazers there. Circumambulate the city of a
    dreamy Sabbath afternoon.

  <code>The code in this pen demonstrates an accessibility friendly technique for employing responsive, fluid typography that respects
    user-defined font sizes. Resize the browser window to see it in action!

  <br />
  <a target="_blank" href="">🤓 Read the full tutorial</a>


                html {
  line-height: 1.5;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
  background-color: #eee;

.container {
  padding: 2rem 4vw;
  max-width: 640px;
  min-height: 100vh;
  margin: 0 auto;

.h1 {
  margin-bottom: 0;

.h1 + p {
  margin-top: 0;

code {
  background-color: #0d5aeb;
  padding: 0.25rem 0.75rem;
  border-radius: 0.25rem;
  color: white;
  border: 2px solid #063b9c;
  font-family: "Fira Code", "Segoe UI", "Roboto", monospace;
  display: flex;
  justify-content: space-between;

#font-size-gauge > div {
  margin: 0.25rem;

#font-size-gauge p {
  margin: 0;
  border-bottom: 3px dotted #73a4ff;

.number {
  font-variant-numeric: oldstyle-nums;
  border: none;

.limit {
  color: yellow;
  font-weight: 700;
#font-size-gauge .number p {
  border: none;

.first-line {
  font-weight: 700;
  font-variant: small-caps;
  font-size: 1.5em;
  float: left;
  margin: 0;
  padding: 1em 0.5em 0 0.25em;

a {
  color: #0d5aeb;



                // Purely for instructional purposes. Remove for production
const fontSizeGauge = document.getElementById("font-size-gauge");

class fluidTypography {
  constructor(minVW, maxVW, minFontSize, maxFontSize) {
    this.minVW = minVW;
    this.maxVW = maxVW;
    this.minFontSize = minFontSize;
    this.maxFontSize = maxFontSize;
    this.maxRem = this.computeRem().maxRem;
    this.minRem = this.computeRem().minRem;

  // Compute the maxRem based on arguments and user's browser preferences
  computeRem() {
    const body = document.documentElement;
    const properties = window.getComputedStyle(body);
    const baseFontSize = properties.fontSize.replace(/px/, '');
    const max = Math.max(this.minFontSize, baseFontSize); // Gets the max font size of either the browser or the dev
    const relativeMax = (this.maxFontSize * max) / this.minFontSize;
    const maxRem = relativeMax / baseFontSize;
    const minRem = max / baseFontSize;
    return { maxRem, minRem };

  // Calculate font size based on arguments and user's browser preferences
  fontSize() {
    const width = document.documentElement.offsetWidth;
    let rem = this.minRem;

    if (width > this.minVW && width < this.maxVW) {
      rem =
        this.minRem +
        ((this.maxRem - this.minRem) * (width - this.minVW)) /
          (this.maxVW - this.minVW);

    if (width > this.maxVW) {
      rem = this.maxRem;
    } = `font-size: ${rem}rem`;

   // Purely for instructional purposes. Remove for production
    const body = document.body;
    const size = window.getComputedStyle(body);
    fontSizeGauge.innerHTML = `
                <div class="number ${rem >= this.maxRem || rem <= this.minRem ? 'limit' : 'no-limit'}"><p>${rem}rem or ${size.fontSize}</p></div>
                <div><p>viewport width</p></div>
                <div class="number"><p>${width}px</p></div>

  resizeHandler() {
    window.addEventListener("resize", this.fontSize.bind(this));

// Instantiate the class
const ft = new fluidTypography(640, 1280, 17.5, 22).resizeHandler();