“Why is your window transparent?” a coworker asked me when she noticed my screen. I told her about how I do my CSS theming, and she pulled another coworker over and made me repeat the explanation. Since that seems like something other people might find handy, here it is.

Sass: Syntactically Awesome Sytlesheets

I rarely do CSS/front-end theming work, but when I do, I try to make it as fun and easy as back-end development. I use Sass (Syntactically Awesome Stylesheets) so that I can use nested selectors, variables, and mixins. This makes my code cleaner and easier to write. You’ll need Ruby in order to install Sass, but the tool will give you CSS that you can use on any web platform.

Browser-based tools

I prefer doing the initial tweaking in Google Chrome, because I like the way that the developer tools make it easy to modify the stylesheet. The Chrome CSS Reloader extension is handy, too. Most of the time, I make my CSS changes in the text editor, then use the CSS Reloader to reload the stylesheet without refreshing the page. This makes it easy to manually toggle the display of some elements while allowing me to refresh style rules. If I want to figure out the values for a few simple changes, I’ll sometimes make the changes directly in Chrome (you can use arrow keys to adjust values), then copy the values to my Sass source file.

Colors, sizes, and spaces

A second monitor is totally awesome and well worth it.

Designs rarely specify all the colours, sizes, and spacing needed. To quickly get the color of a pixel, I use WhatColor. This shows the hex code for colors, and allows me to quickly copy the code with the F12 shortcut key. If you want to change the shortcut key, the source is available as an AutoHotkey script.

To make it easier to match sizes and spaces, I use WinWarden to make my browser window 20% translucent. Then I carefully position it over my design reference until the important features match. Magnifixer makes it easier to line things up because it can magnify a fixed portion of the screen. By focusing Magnifixer on the part I’m working on, I can tweak CSS without straining my eyes.

When I know I’m going to be making a lot of changes, I use AutoHotkey to map a shortcut so that I can refresh the CSS with one keystroke instead of several. When I happen to have my USB foot pedal handy, I rig it up to refresh my stylesheet.

Regression testing

Sometimes my CSS changes modify other rules. Instead of laboriously checking each page after changes, I’ve figured out how to use Selenium WebDriver to write a Java program that loads the pages in Mozilla Firefox and Internet Explorer, capturing screenshots and numbering them according to the pages in my design reference. This means that I can run the program in the background or start it before taking a break, and then flip through all the screenshots when I get back.

Cross-browser testing

What’s CSS theming without the requirement of browser compatibility? Someday, when I need to deal with more browsers, I might look into Selenium RC. In the meantime, I develop in Chrome, my Selenium-based program makes it easier to test in Firefox and IE, and it’s easy enough to try the URLs in Safari as well. Virtual machines handle the rest of the requirements. 

So that’s how I’ve been doing CSS theming on this project. What are your favourite tips?