- Fixes #9113 (caret colors in dropdown buttons)
- Darken borders around buttons for contrast in button groups

Update css.html

.help-block talks about being 'longer', but with .help-inline gone, it's not longer than anything and the comparison is confusing.

Also relevant: http://www.youtube.com/watch?v=Ldyx3KHOFXw

- Spacing tweaks in the general mixins
- Add comments to transform mixins about IE support
- Remove `-ms-keyframes` because only IE10+ supports it, and without
prefix

fixed small typo

its => belonging to it
it's => it is / it has

remove image description from docs

Update documentation on offset for small medium and large devices.

Remove type attribute of tag "script".

- Add new mixin to generate and customize focus state as needed
- Adds variable to set default color
- Include clear disclaimer about customizing this—it's about users', so
don't go making everything bright red and expect them not to be
confused or alarmed.

Relevant issues: #2742, #4185, #7942, #8171, #8610, #9044

Fix #7108: btn group styling

In HTML5 in tag script, the type attribute is no longer required. The default value is "text/javascript".
http://www.w3.org/TR/html5/scripting-1.html#attr-script-type