Redmine 的主题 bs-redmine-theme-dark 感觉还不错, 但是有部分样式看起来不是很舒服, 以下是一些调整:

bs-redmine-theme-dark/stylesheets/application.css
@import url(../../../stylesheets/application.css);
@import url(style.css);
@import url(plugins.css);
@import url(custom.css);#content {padding-top: 4px;
}h1, h2 {margin-bottom: 6px;
}#history .journal.has-notes>div>div {background: #000;
}#history .journal.has-notes>div>div img{width: 22px;
}#content>.contextual a.new-issue, #content>.contextual a.icon-add, #content>.contextual a.icon-edit, #content>.tab-content a.icon-add {background: #0d6f1f;
}select {
#    appearance: none;
}input, input[type="text"], select, textarea, .select2-container--default .select2-selection--single {padding-top: 0;padding-bottom: 0;
}#top-menu {background: color(srgb 0.22 0.2189 0.2189);
}#login-form {width: 100%;color: #181818;
}.tabular ul.tagit li.tagit-choice {background-color: #292929;color: #fff !important;
}.ui-widget-content {color: #000 !important;
}#content {z-index: 15;
}#update {position: fixed;left: 0;top: 30px;right: 0;bottom: 0;background: #000;
}#update .box {height: calc(100% - 136px);overflow: auto;
}#update form input[type="submit"] {margin-left: calc(100% - 200px);
}table.list td {padding-top: 4px;padding-bottom: 4px;
}.parent {min-width: 100px;padding-left: 4px;padding-right: 4px;
}tr.issue .checkbox::before {height: 2em;
}