Dark/Light theme switch

[Bengt]

A setting to switch between light and dark themes as in https://github.com/richrace/highlight-selected would be nice and allow specific color settings. For example using a light theme, I ended up with a "5 % black", which would probably not fit for dark themes:

.editor {
  .line.highlight-line {
    background: rgba(0, 0, 0, 0.05) !important;
  }
}

Here is a screenshot of how that: