CSS ‘schema’ how-to

cssstyling

How does one go about establishing a CSS 'schema', or hierarchy, of general element styles, nested element styles, and classed element styles. For a rank novice like me, the amount of information in stylesheets I view is completely overwhelming. What process does one follow in creating a well factored stylesheet or sheets, compared to inline style attributes?

Best Solution

I'm a big fan of naming my CSS classes by their contents or content types, for example a <ul> containing navigational "tabs" would have class="tabs". A header containing a date could be class="date" or an ordered list containing a top 10 list could have class="chart". Similarly, for IDs, one could give the page footer id="footer" or the logo of the website id="mainLogo". I find that it not only makes classes easy to remember but also encourages proper cascading of the CSS. Things like ol.chart {font-weight: bold; color: blue;} #footer ol.chart {color: green;} are quite readable and takes into account how CSS selectors gain weight by being more specific.

Proper indenting is also a great help. Your CSS is likely to grow quite a lot unless you want to refactor your HTML templates evertime you add a new section to your site or want to publish a new type of content. However hard you try you will inevitably have to add a few new rules (or exceptions) that you didn't anticipate in your original schema. Indeting will allow you to scan a large CSS file a lot quicker. My personal preference is to indent on how specific and/or nested the selector is, something like this: 

    ul.tabs {
    list-style-type: none;
    }
        ul.tabs li {
        float: left;
        }
            ul.tabs li img {
            border: none;
            }

That way the "parent" is always furthest to the left and so the text gets broken up into blocks by parent containers. I also like to split the stylesheet into a few sections; first comes all the selectors for HTML elements. I consider these so generic that they should come first really. Here I put "body { font-size: 77%; }" and "a { color: #FFCC00; }" etc. After that I would put selectors for the main framework parts of the page, for instance "ul#mainMenu { float: left; }" and "div#footer { height: 4em; }". Then on to common object classes, "td.price { text-align: right; }", finally followed by extra little bits like ".clear { clear: both; }". Now that's just how I like to do it - I'm sure there are better ways but it works for me.

Finally, a couple of tips:

  1. Make best use of cascades and don't "overclass" stuff. If you give a <ul> class="textNav" then you can access its <li>s and their children without having to add any additional class assignments. ul.textNav li a:hover {}

  2. Don't be afraid to use multiple classes on a single object. This is perfectly valid and very useful. You then have control of the CSS for groups of objects from more than one axis. Also giving the object an ID adds yet a third axis. For example:

    <style>
div.box {
float: left;
border: 1px solid blue;
padding: 1em;
}

div.wide {
width: 15em; 
}

div.narrow {
width: 8em; 
}

div#oddOneOut {
float: right;
}
</style>

<div class="box wide">a wide box</div>
<div class="box narrow">a narrow box</div>
<div class="box wide" id="oddOneOut">an odd box</div>

  3. Giving a class to your document <body> tag (or ID since there should only ever be one...) enables some nifty overrides for individual pages, like hilighting the menu item for the page you're currently on or getting rid of that redundant second sign-in form on the sign-in page, all using CSS only. "body.signIn div#mainMenu form.signIn { display: none; }"

I hope you find at least some of my ramblings useful and wish you the best with your projects!