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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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Adding Classes

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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

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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-.

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JavaScript

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

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Babel includes JSX processing.

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HTML 

              
                <div class="browser-template">
    <div class="browser-template__top-bar">
        <ul class="browser-template__buttons">
            <li class="browser-template__buttons_item"></li>
            <li class="browser-template__buttons_item"></li>
            <li class="browser-template__buttons_item"></li>
        </ul>
        
        <div class="browser-template__address">
            <svg xmlns="http://www.w3.org/2000/svg"
             viewBox="0 0 448 512">
            <path d="M144 144v48h160v-48c0-44.2-35.8-80-80-80s-80 35.8-80 80zm-64 48v-48C80 64.5 144.5 0 224 0s144 64.5 144 144v48h16c35.3 0 64 28.7 64 64v192c0 35.3-28.7 64-64 64H64c-35.3 0-64-28.7-64-64V256c0-35.3 28.7-64 64-64h16z" />
                            </svg>
                            unicornclub.dev
        </div>
        
        <ul class="browser-template__controls">
            <li class="browser-template__controls_item">
                <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><path fill="currentColor" d="M229.9 473.899l19.799-19.799c4.686-4.686 4.686-12.284 0-16.971L94.569 282H436c6.627 0 12-5.373 12-12v-28c0-6.627-5.373-12-12-12H94.569l155.13-155.13c4.686-4.686 4.686-12.284 0-16.971L229.9 38.101c-4.686-4.686-12.284-4.686-16.971 0L3.515 247.515c-4.686 4.686-4.686 12.284 0 16.971L212.929 473.9c4.686 4.686 12.284 4.686 16.971-.001z"/></svg>
            </li>
            <li class="browser-template__controls_item">
                <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><path fill="currentColor" d="M218.101 38.101L198.302 57.9c-4.686 4.686-4.686 12.284 0 16.971L353.432 230H12c-6.627 0-12 5.373-12 12v28c0 6.627 5.373 12 12 12h341.432l-155.13 155.13c-4.686 4.686-4.686 12.284 0 16.971l19.799 19.799c4.686 4.686 12.284 4.686 16.971 0l209.414-209.414c4.686-4.686 4.686-12.284 0-16.971L235.071 38.101c-4.686-4.687-12.284-4.687-16.97 0z"/></svg>
            </li>
            <li class="browser-template__controls_item">
                <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path fill="currentColor" d="M483.515 28.485L431.35 80.65C386.475 35.767 324.485 8 256.001 8 119.34 8 7.9 119.525 8 256.185 8.1 393.067 119.095 504 256 504c63.926 0 122.202-24.187 166.178-63.908 5.113-4.618 5.353-12.561.482-17.433l-19.738-19.738c-4.498-4.498-11.753-4.785-16.501-.552C351.787 433.246 306.105 452 256 452c-108.321 0-196-87.662-196-196 0-108.321 87.662-196 196-196 54.163 0 103.157 21.923 138.614 57.386l-54.128 54.129c-7.56 7.56-2.206 20.485 8.485 20.485H492c6.627 0 12-5.373 12-12V36.971c0-10.691-12.926-16.045-20.485-8.486z"/></svg>
            </li>
        </ul>
    </div>
    
    <iframe 
        src="https://unicornclub.dev/" 
        width="100%"
        height="100%"
        frameborder="0">
    </iframe>
</div>
!

CSS 

              
                $template-color: #dedede;
$red:     #FF3737;
$yellow:  #FFCE00;
$green:   #32d74b;

.browser-template {
    overflow: hidden;
    border: 2px solid $template-color;
    border-top: none;
    border-radius: 8px;
    box-shadow: 0 4px 10px 1px rgba(darken($template-color, 50%), 0.05);

    &__top-bar {
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        padding: 7px 10px;
        background: $template-color;
    }

    &__buttons {
        display: flex;
        margin: 0;

        &_item {
            width: 10px;
            height: 10px;
            margin-top: 0;
            margin-left: 5px;
            list-style: none;
            border-radius: 100px;
            background: darken($template-color, 10%);

            &:first-child {
                margin-left: 0;
                background-color: $red;
            }

            &:nth-child(2) {
                background-color: $yellow;
            }

            &:nth-child(3) {
                background-color: $green;
            }
        }
    }

    &__address {
        flex-basis: 0;
        flex-grow: 1;
        max-width: 100%;
        height: 23px;
        margin: 0 15px;
        border-radius: 4px;
        background: lighten($template-color, 10%);
        box-shadow: 0 1px 2px 0 rgba(darken($template-color, 50%), 0.05);
        color: darken($template-color, 80%);
        font-size: 12px;
        line-height: 23px;
        text-align: center;

        svg {
            display: inline;
            height: 0.7em;
            margin-right: 1px;
            opacity: 0.8;
            color: darken($green, 10%);
            fill: currentColor;
        }
    }

    &__controls {
        display: flex;
        margin: 0;

        &_item {
            width: 12px;
            height: 12px;
            margin-top: 0;
            margin-left: 10px;
            list-style: none;
            color: darken($template-color, 15%);

            &:first-child {
                margin-left: 0;
            }
        }
    }
}



// Demo
body {
    padding: 15px;
    background: #F7F8FB;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}

.browser-template {
    margin: 0 auto;
    max-width: 1200px;
    height: 95vh;
}

iframe {
    height: calc(100% - 35px);
}
!

JS
!
999px

Console