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HTML

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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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Insecure Resource

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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).

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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.

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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="demo-grid">
    <div class="demo-card">
        <img width="200" height="200" src="https://placekitten.com/200/200?image=1" alt="" class="demo-img">
        <h1 class="line-clamp demo-title">
            Spill litter box, scratch at owner, destroy all furniture, especially couch
        </h1>
    </div>

    <div class="demo-card">
        <img width="200" height="200" src="https://placekitten.com/200/200?image=2" alt="" class="demo-img">
        <h1 class="line-clamp demo-title">
            Claws in the eye of the beholder
        </h1>
    </div>

    <div class="demo-card">
        <img width="200" height="200" src="https://placekitten.com/200/200?image=3" alt="" class="demo-img">
        <h1 class="line-clamp demo-title">
            Relentlessly pursues moth eat too much then proceed to regurgitate all over living room carpet while humans eat dinner
        </h1>
    </div>
</div>
<!-- Titles via http://www.catipsum.com/ -->
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CSS 

              
                /* By default, truncate the text abruptly */
.line-clamp {
    /* Careful computing the max-height, it needs to match n * line-height */
    max-height: calc(2 * 1.15 * 1.5rem);
    overflow: hidden;
}

/* For capable browsers, truncate with an ellipsis */
/* To simulate a browser without support, you can add a s after clamp in the following line */
@supports (-webkit-line-clamp: 2) {
    .line-clamp {
        /* Remove the made up max-height */
        max-height: none;
        
        /* Those three properties are mandatory, so is overflow: hidden that we defined earlier */
        display: -webkit-box;
        -webkit-box-orient: vertical;
        -webkit-line-clamp: 2;
    }
}


/* Extra code for the look of the demo */
.demo-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(13rem,1fr));
    gap: 1rem;
    margin: 1rem;
}
.demo-card {
    background-color: #E2E8F0;
    border-radius: 0.5rem;
    display: flex;
    flex-direction: column;
    padding: 0.5rem;
}
.demo-img {
    align-self: center;
    margin-bottom: 0.5rem;
    border-radius: 0.5rem;
}
.demo-title {
    font-size: 1.5rem;
    margin: 0;
}
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JS
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999px

Console