通过 Less 变量可以自定义颜色、尺寸等，最终将会反映到你所下载的 CSS 样式表文件中。
Gray and brand colors for use across Bootstrap.
Settings for some of the most global styles.
Font, line-height, and color for body text, headings, and more.
Specify custom location and filename of the included Glyphicons icon font. Useful for those including Bootstrap via Bower.
Define common padding and border radius sizes and more. Values based on 14px text and 1.428 line-height (~20px to start).
.table component with basic values, each used across all table variations.