SenCSs - CSS framework that doesn’t provide a layout system (just everything else)
sencss.kilianvalkhof.com
sencss.kilianvalkhof.com
- Sensible defaults for sizing and other attributes that tend to differ across browsers, including typography and such (see Y! CSS Reset)
- Helper classes for forms, info boxes, so on (see Blueprint's forms.css)
- Grid-based layouts to cut down on dev time (see Y! Grids)
Basically, they attempt to cut down on CSS development time by making things equivalent across browsers as well as providing many common styles you would have made anyway. Some also provide various grid-based layouts and others go beyond these things to provide even more, effectively creating something that truly is a framework (I prefer to think of most of them as CSS libraries).
I can't say for sure why you may want to use one, that really depends on the project at hand. One argument can be that you can just run with it without having to define and test your own styles. Also, a framework can eliminate a lot of cross browser issues that may arise and give you consistency across a wide range of browsers.
Oh, and putting Arial before Helvetica is just shameful. Not just because Arial is shameful, but because every system that has Helvetica (i.e. Macs, some Windows users) also has Arial. So as written, Helvetica will never be seen. Likewise for Courier New vs. Courier, or Times New Roman vs. Times. It's nice to declare fonts that look best on each platform, but only if it actually works.
Edit: the sample HTML file gets unaligned after the table, but I think that's because there are some 0.375em paddings scattered around in there (turning those off seem to shore it up nicely).