Improve Kazari design before launch

[jdesiloniz]

Some design twinkering is needed to launch the first version of Kazari:

• Update CSS so the button bar of Kazari correctly attaches itself to the code snippets divs (without any padding as now) (see attachment).
• Avoid Kazari button bar to change paragraphs coming after it (see attachment).
• Also improve Kazari button bar to hide the overlapping border lines at the bottom of the bar.
• The error/success bar should have the corner radius applied only to the bottom corners, as well as being closer to the button bar.
• Take current highlight.js color scheme and apply it to the Kazari button bar.
• Use the same color scheme for the CodeMirror modal editor if possible.

[jdesiloniz]