Style Design Philosophy

DP Style History

The DP codebase has grown very organically over the years, starting out in 2000 when CSS was young and browser support for CSS was very poor. Since that time developers have added new code and styling for code in a variety of ways. In 2017 we updated the entire site codebase to adopt a common look-and-feel using modern CSS.

There are still places in the code that do not follow all the best practices. Due to the nature of DP development this will be an ongoing process for some time.

Style Demo

See the Style Demo page for some examples of oft-used DP styles.

Design Goals


One of the goals of the style redesign was consistency across the site. Fonts, colors, table layouts, page layouts, etc should all be consistent across the site. This means that many pages changed such that all look alike.

Modern CSS

Another goal of the style redesign was using modern CSS. This means getting rid of <font> tags and HTML attributes that specify style and putting all of that into CSS files. We aimed to support CSS 3.0, although most of what we want to implement is actually 2.1. This means that while the site will function on all browsers, older browsers that do not support modern CSS may not get the optimal visual experience.



Pages should generally start with an <h1> header at the top of the page. There are often cases when you might not want a header at all in which case it can be left off. If you need more sections on the page, use increasing header tags to create them (h1 to h2 to h3, etc).

Do not use an <h2> tag as the first tag just because you want smaller text.


Early DP designers were fascinated with centering. Everything was centered. Tables in pages would be less than 100% and centered on the page. Don't do this. In the age of tabs, centering content makes it "jump around" when you have the page up in a background tab, resize the window for the foreground tab, and go back. By left-aligning text the user knows where to look to find the start of page content.


Use tables for showing tabular data and divs for doing layout. Lots of old code still uses tables for layout however.

Don't put table titles in the table. You probably want a header instead.

Table header alignment

For tables with a header row, the header cell alignment should match the data alignment in the rows beneath it. That is, if you have a column of right-aligned data, the table header for that column should also be right-aligned.

Tables with the header cell on the left of the row should be left-aligned. They should also not contain a trailing colon.

Colspan and rowspan alignment

Data in colspan cells that span multiple columns, whether in a header or a regular row, should be center-aligned.

Data in rowspan cells that span multiple rows should be top-aligned.

Re-use existing styles

Give a long, hard thought on why you can't use an existing style before creating a new one. If you're showing an error use the .error class, .warning for a warning. Reuse the existing table styles for new tables.