Currently, this background color is set to a strange dark yellow/green mix (#424200) that is really off-putting. This particular element is shown when moderators post.
When creating a topic, a popup is displayed which shows similar topics. The boarder color is once again #424200. A dark grey might be a better choice for this.
Also a part of the similar topics popup, this css selector’s background color makes it near impossible to read what category the suggested post is in and makes the summary text somewhat difficult to read.
.discourse-tag.simple, .discourse-tag.simple:visited, .discourse-tag.simple:hover
For tagging posts, consider setting the color to something darker such as #5B5B5B. As is, white makes it impossible to read.
Either the background needs to be changed from #700 (burgundy) or the color of the font needs to be switched to something more readible. As is, grey doesn’t work. White however does.
This particular selector doesn’t exist but the .btn-primary being set to #cecece makes the message button on the user-avatar popup somewhat difficult to read, depending on the background of the user. Choosing background: #595959 would resolve this and fit the established color theme as #595959 is already used in the #user-card declarations.
.user-main .user-stream .item.moderator-action
On user streams (in this particular case Oxygen’s), posts that have had a moderator’s action performed on it, inherets an incredibly bright yellow background that makes the block not only unreadable, but incredibly unpleasant to even have on the page.