add 'error_log' to .gitignore file.
add 'width' style to 'content' div.
add 'mobile_support' class.
add more 'translucence options' to fix margin bug.

- add margin-left and margin-right for content and all sidebars.
- make border-width option for content and all sidebars.
- fix 'display.control.js' code to alter the margins when sidebars show
and hide.