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HTML

About HTML Preprocessors

HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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Adding Classes

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html> tag. If you want to add classes there that can affect the whole document, this is the place to do it.

About the <head>

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. If you need things in the <head> of the document, put that code here.

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Insecure Resource

The resource you are linking to is using the 'http' protocol, which may not work when the browser is using https.

CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

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You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself.

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

Add External Scripts/Pens

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You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

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About Packages

Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.

All packages are different, so refer to their docs for how they work.

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HTML 

              
                <div class="overflow__box" id="box">
  <div class="element">
    <h2>Should a classic scrollbar’s scrollbar gutter be present?</h2>
    <p>What is Lorem Ipsum? Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.</p>
    <p dir="rtl" class="content">الكلمة الافتتاحية للمدير العام لمنظمة الصحة العالمية في جلسة الاستماع العامالمتعلقة بوضع صك دولي جديد بشأن التأهب والاستجابة للجائحة - 12 نيسان/ نيسان/أبريل 2022. ولكن حتى ونحن نعمل على القضاء على هذه الجائحة، فإننا ندين لأولئك الذين لقوا حتفهم بسببها وأولئك الذين تضرروا منها بتعلم الدروس المؤلمة التي تقدمها لنا وإدخال التغييرات التي يجب أن نجريها للتأكد من أن العالم متأهب على نحو أفضل للجائحة التالية.</p>
  </div>
</div>

<form>
  <div class="control">
    <label for="overflow">CSS溢出属性:</label>
    <div class="wrapper">
      <select name="overflow" id="overflow">
        <option value="overflow" selected>overflow</option>
        <optgroup label="物理属性">
          <option value="overflow-x">overflow-x</option>
          <option value="overflow-y">overflow-y</option>
        </optgroup>
        <optgroup label="逻辑属性">
          <option value="overflow-inline">overflow-inline</option>
          <option value="overflow-block">overflow-block</option>
        </optgroup>
      </select>
      <span>:</span>
      <select name="value" id="value">
        <optgroup label="Keyword values">
          <option value="visible" selected>visible</option>
          <option value="hidden">hidden</option>
          <option value="clip">clip</option>
          <option value="scroll">scroll</option>
          <option value="auto">auto</option>
        </optgroup>
        <optgroup label="Global values">
          <option value="inherit">inherit</option>
          <option value="initial">initial</option>
          <option value="revert">revert</option>
          <option value="revert-layer">revert-layer</option>
          <option value="unset">unset</option>
          <option value="all">all</option>
        </optgroup>
      </select>
    </div>
  </div>
  <div class="control">
    <label for="direction">direction:</label>
    <select name="direction" id="direction">
      <option value="ltr" selected>ltr</option>
      <option value="rtl">rtl</option>
    </select>
  </div>
  <div class="control">
    <label for="writing-mode">writing-mode:</label>
    <select name="writing-mode" id="writing-mode">
      <option value="horizontal-tb">horizontal-tb</option>
      <option value="vertical-rl">vertical-rl</option>
      <option value="vertical-lr">vertical-lr</option>
    </select>
  </div>
  <div class="control">
    <label for="scrollbar-gutter">scrollbar-gutter:</label>
    <select name="scrollbar-gutter" id="scrollbar-gutter">
      <option value="auto">auto</option>
      <option value="stable">stable</option>
      <option value="stable both-edges">stable both-edges</option>
    </select>
  </div>
  <div class="control">

    <div class="button button--change" id="change">Toggle Size and Content</div>
  </div>
</form>
!

CSS 

              
                @import url("https://fonts.googleapis.com/css2?family=Exo:wght@600&display=swap");

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  width: 100vw;
  min-height: 100vh;
  font-family: "Exo", Arial, sans-serif;
  background-color: #557;
  color: #fff;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--gap);
}

form {
  padding: 1rem;
  background-color: rgb(0 0 0 / 0.6);
  backdrop-filter: blur(20px);
}

.control {
  display: grid;
  grid-template-columns: 8em 1fr;
  gap: 5px;
  align-items: center;
}

.control:not(:last-child) {
  margin-bottom: 1rem;
}

.control label {
  width: min(8em, 100%);
  text-align: right;
}

form select {
  width: clamp(4em, 100%, 9em);
  background: rgb(255 255 255 / 0.3);
  outline: none;
  padding: 10px 2px 10px 10px;
  font-size: 1rem;
  color: #fff;
  text-shadow: 1px 1px 1px rgb(0 0 0 / 30%);
  border: 1px solid rgba(0, 0, 0, 0.3);
  font-family: "Exo", Arial, sans-serif;
  border-radius: 4px;
  box-shadow: inset 0 -5px 45px rgb(100 100 100 / 20%),
    0 1px 1px rgb(255 255 255 / 20%);
  transition: box-shadow 0.5s ease;
}

form select:focus {
  box-shadow: inset 0 -5px 45px rgb(100 100 100 / 40%),
    0 1px 1px rgb(255 255 255 / 20%);
  border-color: #0c69f3;
}

.overflow__box {
  inline-size: 400px;
  max-block-size: 360px;
  border: 1px solid #f9f9f9;
  border-radius: 4px;
  box-shadow: 0 0 1px rgb(0 0 0 / 0.4);
  padding: 2rem;
  margin: auto;
  background-color: rgb(90 120 111 / 0.5);
}

.element {
  padding: 1.2em;
  background: linear-gradient(rgba(255, 255, 255, 0.6) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.6) 1px, transparent 1px),
    linear-gradient(rgba(255, 255, 255, 0.6) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.6) 1px, transparent 1px),
    linear-gradient(
      135deg,
      rgba(84, 232, 220, 1) 0%,
      rgba(241, 231, 103, 1) 25%,
      rgba(240, 229, 104, 1) 50%,
      rgba(254, 182, 69, 1) 75%,
      rgba(250, 118, 47, 1) 100%
    );
  background-size: 20px 20px, 20px 20px, 20px 20px, 20px 20px, 100% 100%;
  background-blend-mode: hard-light, overlay, screen, saturation;
  color: #000;
  letter-spacing: 0.0125em;
  hyphens: auto;
  text-shadow: 1px 1px 0 rgb(255 255 255 / 50%);
  font-size: 1.25em;
}

h2 {
  font-size: clamp(1.2rem, 2vw + 1.5rem, 2rem);
}

.element > * + * {
  margin-block-start: 2rem;
  line-height: 1.6;
}

.overflow__box {
  --direction: ltr;
  --writing-mode: horizontal-tb;
  --scrollbar-gutter: auto;
  direction: var(--direction);
  writing-mode: var(--writing-mode);
  scrollbar-gutter: var(--scrollbar-gutter);
}

.content {
  display: none;
}

.element--wide {
  width: 45vmax;
}

.element--wide .content {
  display: block;
}
.button {
  --background-color: #1b86f9;
  -webkit-appearance: button;
  background-color: var(--background-color);
  border: none;
  color: #fff;
  border-radius: 8px;
  padding: 1em 2em;
  box-shadow: 0 0 0.2em var(--background-color);
  cursor: pointer;
  font-family: "Exo", Arial, sans-serif;
  transition: all 0.28s ease-in-out;
  grid-column: 2 / -1;
  margin-right: auto;
}

.button:focus,
.button:hover {
  --background-color: #3f51b5;
}

@media screen and (max-width: 768px) {
  body {
    grid-template-columns: auto;
    grid-template-rows: 1fr auto;
  }

  form {
    width: 100%;
  }
}
!

JS 

              
                const keyDom = document.querySelector("#overflow");
const valueDom = document.querySelector("#value");
const boxDom = document.querySelector("#box");
const dirDom = document.querySelector("#direction");
const writingMode = document.querySelector("#writing-mode");
const scrollbarGutter = document.querySelector("#scrollbar-gutter");
const toggleButton = document.querySelector(".button");
const ele = document.querySelector(".element");

let key, value;

function setStyle() {
  boxDom.style = {};
  boxDom.style.setProperty(`${key}`, `${value}`);
}

window.addEventListener("load", () => {
  key = keyDom.value;
  value = valueDom.value;
  setStyle();
});

keyDom.addEventListener("change", () => {
  key = keyDom.value;
  console.log("key===>", key);
  setStyle();
});

valueDom.addEventListener("change", () => {
  value = valueDom.value;
  setStyle();
});

[dirDom, writingMode, scrollbarGutter].forEach((selector) => {
  selector.addEventListener("change", (etv) => {
    boxDom.style.setProperty(`--${etv.target.id}`, `${etv.target.value}`);
  });
});

toggleButton.addEventListener("click", () => {
  ele.classList.toggle("element--wide");
});
!
999px

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