CSS3

  • 200730 Jul

    A mock-up interface using CSS3 Colour

    by David Storey

    Posted in Modules, Tutorials

    I recently posted a preview of the CSS3 colour module on my own blog, but avoided using any actual examples. This was because of the things that have been implemented, the true power isn’t really seen using a simple example. With opacity and the HSLA/RGBA colour models, any elements that have been coloured just look like they fade to a lighter tint if there is only a white background behind it. Support for SVG colour keywords has also existed for a long time, just without being accepted by the validator.

    To show the true flexibility of CSS3 colour, I had to build a more complex example with overlapping elements. I also added a number of other CSS3 properties to show case them while I was at it (Why not?). Due to using a lot of transparency, there are a number of issues with Minefield, where it crawls to a hault then eventually stops responding. This may only be a issue with the Mac build or my hardware, so your mileage may vary. There shouldn’t be any issues with using webKit, except for a number of bugs that I seem to have uncovered. Most of these were hi-lighted in my previous post.

    Without further ado, here is the example for you to try out (warning large background image). It is based on a loose mock-up of a Mac OS X Leopard style interface. I needed a background image, so took a wallpaper from Michael Palin’s great Sahara series. The photo is copyright Basil Pao and is of a mother and her child in Tabelot, Niger.

    Because the example was designed to showcase the various colour values, I’ve mixed between using opacity, HSL, HSLA, RGB, RGBA (both hex and percentage) and keywords. In a real production site I’d have avoided this and stuck with the same colour models where appropriate. I tend to use keywords myself as they are easier (for me) to remember. HSL (and by extension HSLA) would be very useful when greater control over the colour is needed, but at the current moment it isn’t supported enough to be used. The correct RGB value would have to be used anyway to act as a fallback colour.

    The example showcases the difference between HSLA/RGBA and opacity. If you hover over the File or Go menus, I’ve added a sub menu that has opacity applied too it. When hovering over a menu item that is displayed over the white title bar behind it, you’ll notice the text is more white than the text with the mud background behind. This is because opacity is set on the foreground and well as the background. for elements that have been styled using HSLA or RGBA on the background colour, such as the faux-window title bars, contents area and menu bar, retain fully opaque text. While the difference isn’t too great with this example, there can be cases where the difference is quite obvious. It also allows things like just the shadows to have transparency.

    I’ve included quite a lot of other CSS3 into the mix. There is liberal use of box-shadow to give the allusion of depth on the windows and title bar. Rounded corners have been added to windows. There is an issue with rounded corners, where if overflow is set (which adds scroll bars) then the corner with the scroll bar ignores the radius (or is displayed behind it). I moved the overflow to a div inside the faux-windows to avoid this problem. I’m not sure how browsers can be fixed to avoid this problem without the spec changing to accommodate things like scroll bars. resize was added to both faux-windows, but there is issues with each element inside the window being resizable independently in Safari, and not being able to resize it smaller (the later wasn’t an issue in earlier builds).

    One of the big compatibility issues with current browser support is the difference between overflow using multi column layout. In Safari it doesn’t respect the setting of having two columns, by adding extra columns to the right of the visible columns. This seems smart at first as it avoids the issue of having to scroll to the bottom of the first column and back up to the start of the next column, however it is generally harder to scroll horizontally than vertically. You can also imagine if a height was set and overflow wasn’t used then it could push any content to the right of the columns out of view, such as a right hand side bar. Minefield just uses the two specified columns and makes the content as long as needed. This has issues as you get the scrolling problem mentioned previously. This will be a usability annoyance. My only suggestion is that a column height can be set, and when all available space is taken up without scrolling, a column break is inserted and columns of the same width and height are repeated below until the content runs out. There would have to be some way to specify the vertical column gap though. This would solve the readability issue, a one block of columns could be read at one time, and it will stop and important right sided content (or left in rtl layouts) from being pushed off the screen.

    The next CSS3 used was background-size. This was set at 100% so that no matter how big or small the browser window is, all the background image is shown (overflow:hidden; had to be added as the very latest versions of WebKit add scroll bars, unlike previous versions). This currently only works in WebKit. While most of this works fine in WebKit (if you ignore the bugs), one thing that only works in Opera and KHTML is the menu separators. Instead of adding mark-up such as a br I used the nth-child selector to select the exact element where the separator should go, and added the appropriate margin, border and padding. Without there being an element to group related list items, I though this was the best way to go about it, plus it was another excuse to show off more CSS3. Finally I used a attribute selector to grey out the print menu option (or any option in the menu with a URL of #). This is a bit of a hack to demonstrate the technique, but you can see how it could be useful in the real world.

    The great power I see coming with CSS3 is that this example looks fairly complex and flashy, yet only uses one image (the background image), and the mark-up is very brief. I could have used even less mark-up and ID/Class attributes, but they were added for semantic meaning. The problem is more that the browser has to do much more processing to work out things like the transparencies so there can be performance issues, especially on older hardware. One can expect that performance will be tuned as support for the new properties are included in final releases.

    You can skip to the end and leave a response.

  • Comments

Leave a Comment

(will not be published)

Subscribe to our RSS

OUR SPONSORS

Advertise here?
CATEGORIES
FRIENDS
Meta
TAG CLOUD acid3 advanced layout advanced layout module background border Browsers color css CSS3.info CSS WG csswg developer tools disabled enabled Feedback firefox firefox 3.1 flexible box layout fonts generated content grid positioning HSLA HTML5 ie6 ie7 jina bolton jquery media player Multicolumn Layout News Opera Opera Dragonfly presentations RGBA safari Selectors slides SVG text rendering W3C wasp Web Fonts webkit windows

Hosting by:

© 2009 WEBFLUX. All Rights Reserved. Theme by W3 EDGE, WordPress Experts