Change Sidebar Colour

See this thread: http://ww.wp.xz.cn/support/topic/sidebar-80?replies=2#post-5047331

An easy way to add custom CSS is to install the Jetpack plugin and activate the Custom CSS module. You’ll then add your custom CSS in the new stylesheet editor that’ll appear in your dashboard, under Appearance > Edit CSS.

As alternatives, you could either install a standalone custom CSS plugin, or create a child theme.

If you use a custom CSS plugin – the easiest route – you shouldn’t need to use !important.