As noted by @onenaa you need to state the name and full version number of the story format you are using as answers can be different for each one, and I suggest using the question tag system to do this instead of adding that information to the question title.
Based on the name of some of the selectors in your example CSS I will assume you are using Harlowe, unfortunately when it comes to CSS knowing the series (1.x or 2.x) can be important because they have slightly CSS defaults and HTML structures. Now that you have added a story format name and version tag we know which you're using.
Besides the issues pointed out by @Chapel I also noticed the following:
1. If you are hiding the tw-sidebar element then you don't need to also hide the .redo and .undo classed child elements, because they will automatically be hidden when their parent is.
eg. Delete the following two child rules.
.redo { display:none; }
.undo { display:none; }
... and leave in the parent rule:
tw-sidebar {
display: none;
}
edit: After seeing that the harlowe2.0.1 tag has been added to the question
2. It is unclear in your example which element you background image & colour attributes are targeting.