Pen Settings

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.

Learn more · Versions

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.

!
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.

Learn more · Versions

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.

Powered by Algolia
About External Resources

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.

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

Learn more

+ add another resource

JavaScript

About JavaScript Preprocessors

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

Learn more · Versions

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

Powered by Algolia
About External Resources

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.

Learn more

+ add another resource

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.

Powered by Algolia
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.

If you're using React / ReactDOM, make sure to turn on Babel for the JSX processing.

Behavior

Auto Save

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML 

              
                <h1>Smart Scrollbar Example</h1>

<div id="container">Lorem ipsum dolor sit amet, te eos facilis noluisse consetetur. Ei quodsi labitur vulputate vix. Vix no nisl ornatus, discere consequat te mea. Cu ius quem ferri assueverit, cu sit nulla persequeris concludaturque. Vim ut sale causae referrentur.

    Id habemus pertinacia ius, mea fastidii convenire at. At sit postulant repudiandae, has ut natum delicatissimi. Quo liber veritus ponderum ea, his cu corrumpit consequuntur. Et cum apeirian percipitur, invidunt salutatus ex ius. Mea exerci conceptam ad, at vim accusata adipiscing.

    Nam decore docendi cu, vide liber accusam eam ei, at quando malorum sapientem vis. Eam te hinc facer. Eu usu option intellegat, cibo debitis graecis sed ei, consul tempor id pri. Quo at dicam electram, qui ut nonumy nonumes constituam. Eos nibh quaestio efficiendi an, munere argumentum ei vix, ex cum nisl novum gubergren. Vix in veniam propriae, labitur sadipscing eu mel.

Qui ut ubique placerat euripidis. His esse eius ne, ut docendi gloriatur posidonium quo. Et inermis ceteros ius, ea pro novum ignota vivendo. Cum id vide laudem, augue inermis definitiones mea at, phaedrum dissentiunt te per.

Conceptam ullamcorper an mea, autem idque pri in. Duo homero delenit no, aperiri aliquando ei vel, scripta interesset usu ut. Iriure aliquip vivendum an sit, mea molestie consulatu democritum ne, in vix virtute vivendo petentium. Vix an habeo partem ullamcorper, in mei dissentiunt concludaturque. Ipsum accusata incorrupte vix an, an sed ferri tritani voluptatibus.

Putent nostrud in ius, dicta consectetuer has ex. Ad tota graeco comprehensam pri, usu reque nobis aliquando ut. Eam ut viderer quaestio accusamus, audire menandri conclusionemque ex vim. Ius ex solet fuisset, ei dicta iudico mel. No eum vivendo volutpat expetenda, menandri iracundia ea vim.

Fugit detracto liberavisse vel an, has an amet accusam. Mei facer intellegam te, nec forensibus adipiscing ex. Iusto aperiri an his. Ei cum bonorum dolorum, enim atqui ex cum.

Invenire interpretaris ei pri, omnes tantas vidisse at ius, essent vidisse et mel. Illud partiendo referrentur cu has, aliquip impedit vim no. Ex mel veritus antiopam. Habeo utinam quidam per ne. Dolorem ancillae vim ex, te quidam ornatus propriae duo. Dictas eripuit ex eam, ut reque choro maluisset usu.

An debet inermis eam. Mei dicit munere ex. Posse disputando et per. In mundi iuvaret evertitur nec, cu simul impedit volumus mel. His meis vidisse adolescens at.

Cibo placerat maiestatis ne est, vix ad mollis civibus dolores, nemore nostro sed no. No decore tempor persecuti eum, eirmod inermis laboramus no mei. Ei suas euripidis honestatis vis. Impedit singulis corrumpit nec ex. At duo sint delicata, ea justo dolor per.
    
    Lorem ipsum dolor sit amet, te eos facilis noluisse consetetur. Ei quodsi labitur vulputate vix. Vix no nisl ornatus, discere consequat te mea. Cu ius quem ferri assueverit, cu sit nulla persequeris concludaturque. Vim ut sale causae referrentur.

Id habemus pertinacia ius, mea fastidii convenire at. At sit postulant repudiandae, has ut natum delicatissimi. Quo liber veritus ponderum ea, his cu corrumpit consequuntur. Et cum apeirian percipitur, invidunt salutatus ex ius. Mea exerci conceptam ad, at vim accusata adipiscing.

Nam decore docendi cu, vide liber accusam eam ei, at quando malorum sapientem vis. Eam te hinc facer. Eu usu option intellegat, cibo debitis graecis sed ei, consul tempor id pri. Quo at dicam electram, qui ut nonumy nonumes constituam. Eos nibh quaestio efficiendi an, munere argumentum ei vix, ex cum nisl novum gubergren. Vix in veniam propriae, labitur sadipscing eu mel.

Qui ut ubique placerat euripidis. His esse eius ne, ut docendi gloriatur posidonium quo. Et inermis ceteros ius, ea pro novum ignota vivendo. Cum id vide laudem, augue inermis definitiones mea at, phaedrum dissentiunt te per.

Conceptam ullamcorper an mea, autem idque pri in. Duo homero delenit no, aperiri aliquando ei vel, scripta interesset usu ut. Iriure aliquip vivendum an sit, mea molestie consulatu democritum ne, in vix virtute vivendo petentium. Vix an habeo partem ullamcorper, in mei dissentiunt concludaturque. Ipsum accusata incorrupte vix an, an sed ferri tritani voluptatibus.

Putent nostrud in ius, dicta consectetuer has ex. Ad tota graeco comprehensam pri, usu reque nobis aliquando ut. Eam ut viderer quaestio accusamus, audire menandri conclusionemque ex vim. Ius ex solet fuisset, ei dicta iudico mel. No eum vivendo volutpat expetenda, menandri iracundia ea vim.

Fugit detracto liberavisse vel an, has an amet accusam. Mei facer intellegam te, nec forensibus adipiscing ex. Iusto aperiri an his. Ei cum bonorum dolorum, enim atqui ex cum.

Invenire interpretaris ei pri, omnes tantas vidisse at ius, essent vidisse et mel. Illud partiendo referrentur cu has, aliquip impedit vim no. Ex mel veritus antiopam. Habeo utinam quidam per ne. Dolorem ancillae vim ex, te quidam ornatus propriae duo. Dictas eripuit ex eam, ut reque choro maluisset usu.

An debet inermis eam. Mei dicit munere ex. Posse disputando et per. In mundi iuvaret evertitur nec, cu simul impedit volumus mel. His meis vidisse adolescens at.

Cibo placerat maiestatis ne est, vix ad mollis civibus dolores, nemore nostro sed no. No decore tempor persecuti eum, eirmod inermis laboramus no mei. Ei suas euripidis honestatis vis. Impedit singulis corrumpit nec ex. At duo sint delicata, ea justo dolor per.
    
    Lorem ipsum dolor sit amet, te eos facilis noluisse consetetur. Ei quodsi labitur vulputate vix. Vix no nisl ornatus, discere consequat te mea. Cu ius quem ferri assueverit, cu sit nulla persequeris concludaturque. Vim ut sale causae referrentur.

Id habemus pertinacia ius, mea fastidii convenire at. At sit postulant repudiandae, has ut natum delicatissimi. Quo liber veritus ponderum ea, his cu corrumpit consequuntur. Et cum apeirian percipitur, invidunt salutatus ex ius. Mea exerci conceptam ad, at vim accusata adipiscing.

Nam decore docendi cu, vide liber accusam eam ei, at quando malorum sapientem vis. Eam te hinc facer. Eu usu option intellegat, cibo debitis graecis sed ei, consul tempor id pri. Quo at dicam electram, qui ut nonumy nonumes constituam. Eos nibh quaestio efficiendi an, munere argumentum ei vix, ex cum nisl novum gubergren. Vix in veniam propriae, labitur sadipscing eu mel.

Qui ut ubique placerat euripidis. His esse eius ne, ut docendi gloriatur posidonium quo. Et inermis ceteros ius, ea pro novum ignota vivendo. Cum id vide laudem, augue inermis definitiones mea at, phaedrum dissentiunt te per.

Conceptam ullamcorper an mea, autem idque pri in. Duo homero delenit no, aperiri aliquando ei vel, scripta interesset usu ut. Iriure aliquip vivendum an sit, mea molestie consulatu democritum ne, in vix virtute vivendo petentium. Vix an habeo partem ullamcorper, in mei dissentiunt concludaturque. Ipsum accusata incorrupte vix an, an sed ferri tritani voluptatibus.

Putent nostrud in ius, dicta consectetuer has ex. Ad tota graeco comprehensam pri, usu reque nobis aliquando ut. Eam ut viderer quaestio accusamus, audire menandri conclusionemque ex vim. Ius ex solet fuisset, ei dicta iudico mel. No eum vivendo volutpat expetenda, menandri iracundia ea vim.

Fugit detracto liberavisse vel an, has an amet accusam. Mei facer intellegam te, nec forensibus adipiscing ex. Iusto aperiri an his. Ei cum bonorum dolorum, enim atqui ex cum.

Invenire interpretaris ei pri, omnes tantas vidisse at ius, essent vidisse et mel. Illud partiendo referrentur cu has, aliquip impedit vim no. Ex mel veritus antiopam. Habeo utinam quidam per ne. Dolorem ancillae vim ex, te quidam ornatus propriae duo. Dictas eripuit ex eam, ut reque choro maluisset usu.

An debet inermis eam. Mei dicit munere ex. Posse disputando et per. In mundi iuvaret evertitur nec, cu simul impedit volumus mel. His meis vidisse adolescens at.

Cibo placerat maiestatis ne est, vix ad mollis civibus dolores, nemore nostro sed no. No decore tempor persecuti eum, eirmod inermis laboramus no mei. Ei suas euripidis honestatis vis. Impedit singulis corrumpit nec ex. At duo sint delicata, ea justo dolor per.
</div>

<script>
    addEventListener("load", () => smartScrollbar("#container"));
</script>
!

CSS 

              
                body {
    display: flex;
    flex-direction: column;
    align-items: center;
    
    background-color: whitesmoke;
    
    font-family: Cambria;
}

#container {
    position: relative;
    
    box-sizing: border-box;
    
    width: 75vw;
    height: 27rem;
    
    max-height: 90vh;
    
    text-indent: 2rem;
    
    padding: 0.25rem;
    padding-right: 2rem;
    
    border: 2px solid black;
    
    overflow-y: hidden;
    
    white-space: pre-wrap;
}
!

JS 

              
                var smartScrollbar = (function(){ 
    function smoothScroll(element, to, duration)
    {
        let ticks = Math.ceil(duration / 60), 
            top = element.scrollTop;
        
        to = Math.max(Math.min(top + to, element.scrollHeight), 0);
        
        let diff = to - top,
            delta = diff / ticks,
            tick;
        
        let fn = () => {
            if(--ticks)
                requestAnimationFrame(fn);
            
            top += delta;
            
            element.scrollTop = top;
            
            calculatePosition(element);            
        };
        
        fn();
    }
    
    function calculateHeight(element)
    {
        let scrollbar = element.scrollbar;
        
        let rect = offset(element), scr = scroll(element);

        let height = rect.height;

        let ratio = height / scr.height, scaledHeight = ratio * rect.height;

        scrollbar.style.height = `${scaledHeight}px`;

        calculatePosition(element, rect, scr);
    }

    function calculatePosition(element, rect, scr)
    {
        let scrollgutter = element.scrollgutter, scrollbar = element.scrollbar;
        
        rect = rect || offset(element);
        scr = scr || scroll(element);

        let scrollbarRect = offset(scrollbar), scrollbarHeight = scrollbarRect.height;

        let top = scr.top;

        let scrollHeight = scr.height, comp = computed(element);

        let internalHeight = rect.height - (parseInt(comp.borderTopWidth) + parseInt(comp.borderBottomWidth));

        let newTop = Math.max(Math.min(top / scrollHeight * internalHeight, internalHeight - scrollbarHeight), 0);

        scrollgutter.style.top = top + "px";
        scrollbar.style.top = newTop + "px";
    }
    
    function vanishScrollbar(scrollbar, delay)
    {
        return setTimeout(() => scrollbar.style.opacity = "0", delay);
    }

    return function(target, options)
    {
        options = options || {};
        
        target = E1(target);
        
        var scrollgutter = create("div", {
            className: "smart-scroll-gutter"            
        });
        
        var scrollbar = create("div", {
            className: "smart-scrollbar",
            
            onmousedown: function(e)
            {
                this.setAttribute("data-drag-offset", e.offsetY);
                this.dragging = true;
            }
        });
        
        let gstyle = scrollgutter.style;
        
        gstyle.width = options.width || "8px";
        gstyle.height = "100%";
        
        gstyle.position = "absolute";
        gstyle.right = "2px";
        gstyle.top = "0";
        
        gstyle.pointerEvents = "auto";
        gstyle.userSelect = "none";
        
        let style = scrollbar.style;
        style.position = "absolute";
        style.top = "0";
        
        style.width = "100%";
        style.backgroundColor = options.backgroundColor || "#A0A0A0";
        style.opacity = "0";
        
        style.transition = "opacity 0.5s"
        
        on(scrollgutter, "mouseenter", (e) => {
            // Don't show the scrollbar if the scrollHeight and offsetHeight are the same
            if(target.scrollHeight == target.offsetHeight)
                return;
            
            calculateHeight(target);
            calculatePosition(target);
            
            clearTimeout(target.scrollbarVanish);
            
            style.opacity = "1";
        });

        on(scrollgutter, "mouseleave", (e) => {
            if(!scrollbar.dragging)
                target.scrollbarVanish = vanishScrollbar(scrollbar, 1000);
        });

        on(target, "wheel", (e) => {
            let target = e.currentTarget;
            
            // Don't do any scrolling if the scrollHeight and offsetHeight are the same
            if(target.scrollHeight == target.offsetHeight)
                return;
            
            let scr = scroll(target);

            let scrollAmount = e.deltaY;
            
            calculateHeight(target);
            
            smoothScroll(target, scrollAmount, 500);
            
            calculatePosition(target);
            
            clearTimeout(target.scrollbarVanish);
            
            style.opacity = "1";
        }, {
            passive: true
        });
        
        on("mousemove", (e) => {            
            if(scrollbar.dragging)
            {
                let rect = offset(target), comp = computed(target);

                let scrollHeight = target.scrollHeight,
                    internalHeight = rect.height - (parseInt(comp.borderTopWidth) + parseInt(comp.borderBottomWidth)),
                    scrollAmount = Math.min(Math.max((e.clientY - rect.top) - parseInt(scrollbar.dataset.dragOffset), 0), scrollHeight);
                
                target.scrollTop = (scrollAmount / internalHeight) * scrollHeight;
                
                calculatePosition(target);
            }
        });
        
        on("mouseup", (e) => {
            if(scrollbar.dragging)
            {
                scrollbar.removeAttribute("data-drag-offset");
                scrollbar.dragging = false;
                
                if(e.target != scrollgutter && !scrollgutter.contains(e.target))
                    target.vanishScrollbar = vanishScrollbar(scrollbar, 1000)
            }
        });
        
        target.scrollgutter = scrollgutter;
        target.scrollbar = scrollbar;
        scrollgutter.appendChild(scrollbar);
        target.appendChild(scrollgutter);
        
        calculateHeight(target);
    }
})();
!
999px

Console