path: root/posts/flexbox-bar-graphs.md

# Pure CSS Bar Graphs with Graceful Mobile Fallbacks

2020-12-08

I recently published a new open source project, <a target="_blank" href="https://flexbox-bar-graphs.netlify.app/">Flexbox Bar Graphs</a>, and wanted to share a simple breakdown of how it was built. It isn't anything mind-blowing, but I like the idea of placing bar graphs in a web page with *zero* Javascript.

So in the end, this is what our bar graphs will look like on desktop:

<figure>
    <img src="/public/images/flexbox-bar-graph-1.webp" alt="Flexbox Bar Graph">
    <figcaption>The flexbox bar graph in desktop view (<a href="/public/images/flexbox-bar-graph-1.webp">direct link to image</a>)</figcaption>
</figure>

And this is how it will look on smaller devices:

<figure>
    <img src="/public/images/flexbox-bar-graph-2.webp" alt="Flexbox Bar Graph Table">
    <figcaption>The flexbox bar graph on mobile devices (<a href="/public/images/flexbox-bar-graph-2.webp">direct link to image</a>)</figcaption>
</figure>

Let's get into the details!

## The HTML

The main "secret" of this project is that our graphs are constructed out of HTML *tables*. Now before you freak out - this is perfectly fine and works in our favor quite well.

1. If the user has JS disabled --> they will still see our graphs
2. If the user has CSS disabled --> they will see a standard data table set

All bases are covered!


    <!-- Using a basic table with our custom data-id -->
    <table data-id="flexbox-bar-graph">
        <caption>Web Performance Results</caption>
        <thead>
            <tr>
                <th>Test Performed</th>
                <th>Before</th>
                <th>After</th>
                <th>Difference</th>
            </tr>
        </thead>
        <tbody>
            <tr>
                <th>Initial Load Time</th>
                <td>
                    <!--
                        WTF are these CSS variables?
                        See the CSS section below
                    -->
                    <span style="--data-set:4.7/5;"></span>
                    <p>4.7</p>
                </td>
                <td>
                    <span style="--data-set:2.7/5;"></span>
                    <p>2.7</p>
                </td>
                <td>
                    <span style="--data-set:2/5;"></span>
                    <p>2</p>
                </td>
            </tr>
        </tbody>
    </table>


Nothing crazy is happening here - just your standard HTML table structure. The one main thing to notice is the `--data-set` CSS variable placed inline on each data point. This will be important for our CSS to configure the individual bar graphs properly.

## The CSS

This might look overwhelming if I just dumped the whole CSS file in one big code block, so instead I'm going to break them down into two parts:

1. Baseline styling (mobile)
2. Desktop styling

### Baseline

Here we target just our table elements with the `data-id` of `flexbox-bar-graph`. This allows us to avoid worrying about adding classes or IDs and also avoids conflicts with other non-graph styled tables in our projects.

The base `:root` element holds all of our bar graph colors. Change these as you see fit!


    /* Bar Graph color variables */
    :root {
        --bar-color-1: #357EC7;
        --bar-color-2: #E42217;
        --bar-color-3: #4CC417;
        --bar-color-4: #7D0541;
        --bar-color-5: #FFD801;
    }

    [data-id="flexbox-bar-graph"] {
        border-collapse: collapse;
        margin: 4rem 0 6rem;
        width: 100%;
    }
    [data-id="flexbox-bar-graph"] caption {
        text-align: left;
    }
    [data-id="flexbox-bar-graph"] thead th {
        text-align: right;
    }
    [data-id="flexbox-bar-graph"] thead th:nth-child(1),
    [data-id="flexbox-bar-graph"] tbody th {
        text-align: left;
    }
    [data-id="flexbox-bar-graph"] tbody th {
        font-weight: normal;
        font-style: italic;
    }
    [data-id="flexbox-bar-graph"] tbody td {
        text-align: right;
    }
    [data-id="flexbox-bar-graph"] tbody td p {
        margin: 0;
    }


### Desktop

Now we set your "visual" bar graphs to show at a set width (in this example it is 1000px and above). That way the "default" styling can target the mobile device screen sizes.

- The `thead tr th:nth-child(x):before` elements create the square "legends" beside each individual data point heading
- The `tbody tr td:nth-of-type(x) span` elements are the bars themselves


    @media(min-width: 1000px) {
        [data-id="flexbox-bar-graph"] {
            background: transparent;
            display: block;
            min-height: 400px;
            padding: 0;
            position: relative;
            width: 100%;
        }
    
        [data-id="flexbox-bar-graph"] caption {
            display: block;
            font-size: 2rem;
            text-align: center;
            width: 100%;
        }
    
        [data-id="flexbox-bar-graph"] thead {
            display: block;
            margin: 2rem 0 3rem;
            width: 100%;
        }
        [data-id="flexbox-bar-graph"] thead tr {
            border-bottom: 1px solid lightgrey;
            display: flex;
            justify-content: center;
            padding-bottom: 1rem;
        }
    
        [data-id="flexbox-bar-graph"] thead tr th {
            display: inline-block;
            margin: 0;
            padding: 0;
            position: relative;
            text-align: right;
        }
        [data-id="flexbox-bar-graph"] thead tr th:before {
            content:'';
            display: inline-block;
            height: 10px;
            margin: 0 0.5rem 0 2rem;
            position: relative;
            width: 10px;
        }
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(1),
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(1):before {
            display: none;
        }
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(2):before {
            background: var(--bar-color-1);
        }
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(3):before {
            background: var(--bar-color-2);
        }
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(4):before {
            background: var(--bar-color-3);
        }
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(5):before {
            background: var(--bar-color-4);
        }
        [data-id="flexbox-bar-graph"] thead tr th:nth-child(6):before {
            background: var(--bar-color-5);
        }
    
        [data-id="flexbox-bar-graph"] tbody {
            display: flex;
            justify-content: space-between;
            min-height: 300px;
            width: 100%;
        }
    
        [data-id="flexbox-bar-graph"] tbody tr {
            display: flex;
            flex-direction: column-reverse;
            flex-wrap: wrap;
            justify-content: flex-end;
            padding: 0 50px;
            position: relative;
            width: 100%;
        }
        [data-id="flexbox-bar-graph"] tbody tr th {
            font-size: 90%;
            position: absolute;
            text-align: center;
            top: 100%;
            width: calc(100% - 100px);
        }
        [data-id="flexbox-bar-graph"] tbody tr td {
            align-items: center;
            display: flex;
            flex-direction: column;
            height: 95%;
            justify-content: flex-end;
        }
    
        [data-id="flexbox-bar-graph"] tbody tr td span {
            display: block;
            height: calc(var(--data-set) * 100%);
            width: 20px;
        }
        [data-id="flexbox-bar-graph"] tbody tr td:nth-of-type(1) span {
            background: var(--bar-color-1);
        }
        [data-id="flexbox-bar-graph"] tbody tr td:nth-of-type(2) span {
            background: var(--bar-color-2);
        }
        [data-id="flexbox-bar-graph"] tbody tr td:nth-of-type(3) span {
            background: var(--bar-color-3);
        }
        [data-id="flexbox-bar-graph"] tbody tr td:nth-of-type(4) span {
            background: var(--bar-color-4);
        }
        [data-id="flexbox-bar-graph"] tbody tr td:nth-of-type(5) span {
            background: var(--bar-color-5);
        }
    
        [data-id="flexbox-bar-graph"] tbody tr td p {
            font-size: 90%;
            margin: 0;
            text-align: center;
        }
    }


## Bonus Styling

In the <a target="_blank" href="https://github.com/bradleytaunt/flexbox-bar-graphs">Flexbox Bar Graph</a> repo, I've also included the ability to display these bar graphs horizontally, like so:

<figure>
    <img src="/public/images/flexbox-bar-graph-3.webp" alt="Flexbox Bar Graph Horizontal">
    <figcaption>The flexbox bar graph in the horizontal layout (<a href="/public/images/flexbox-bar-graph-3.webp">direct link to image</a>)</figcaption>
</figure>

The change in CSS is actually quite simple to pull this off - you just need to include the `data-layout` attribute on the table itself.


    [data-layout="horizontal"] tbody {
        min-height: auto;
    }
    
    [data-layout="horizontal"] tbody tr {
        flex-direction: column;
        padding: 0 40px;
    }
    [data-layout="horizontal"] tbody tr th {
        width: calc(100% - 80px);
    }
    
    [data-layout="horizontal"] tbody tr th {
        text-align: left;
        top: calc(100% + 20px);
    }
    
    [data-layout="horizontal"] tbody tr td {
        flex-direction: row;
        height: auto;
        justify-content: start;
        margin: 10px 0;
    }
    
    [data-layout="horizontal"] tbody tr td span {
        height: 20px;
        width: calc(var(--data-set) * 100%);
    }
    
    [data-layout="horizontal"] tbody tr td p {
        margin-left: 10px;
    }


## That's All Folks!

That just about sums things up. Feel free to check out the Github repo itself, open any issues you find or fork it for your own!

- Github: <a href="https://github.com/bradleytaunt/flexbox-bar-graphs">https://github.com/bradleytaunt/flexbox-bar-graphs</a>
- Live Demo: <a href="https://flexbox-bar-graphs.netlify.app/">https://flexbox-bar-graphs.netlify.app/</a>