The framework is written in less. The css is just the rendered version of the less framework. You can configure variables to choose colors, curvatures, font ba

The framework is written in less. The css is just the rendered version of the less framework. You can configure variables to choose colors, curvatures, font base heights etc. the math performed in less scales elements and padding to the base height. There are a lot if edge cases and browser issues that are noticed and fixed by the larger community. You can also break the framework apart easily and only include certain parts by includes in the master style sheet. I'm personally using the sass fork And I have the js and CSS pared down to reduce the overall size, customize navbars etc. It's definitely a framework.