How do i set custom colors for active and inactive title bars, Windows 2000-style, in Windows 8.1?
I do not want to enable high contrast mode, because it makes Internet Explorer unusable.
You cannot do it easily - not a feature provided by Microsoft. However there are couple of options for you:
This is probably the best one based on your requirements
Second option, which is not exactly what you are asking for but could still help
At the risk of getting under-voted, this is the answer according to my knowledge :
In Windows 8.1, registry options are available only for high contrast themes.
Some third-party tools will help you with that task, for example WindowBlinds ($7.49, trial available).