As of 855b0d5 LOOT will use the windowsvista Qt style on Windows 10 and 11 by default, but it doesn't follow the system colour scheme, so LOOT's dark theme ends up looking quite different to the light theme (aside from colours) as it needs to restyle a lot of controls to change their colours.

Qt said that the Fusion style was their preferred style for Windows 11 as of Qt 6.5, but then introduced the windows11 style in Qt 6.7. The windows11 style, like the Fusion style, does follow the system colour scheme, and looks OK in the dark colour scheme on Windows 11, but looks terrible in Windows 11's light colour scheme (which is why LOOT forces windowsvista instead). Although you'd think that the windows11 style looks like native Windows 11 controls (whatever that means, considering how inconsistent Windows 11's GUI is), it actually comes across as more of a poor knock-off, even in dark mode.

Compared to the windowsvista style, the Fusion style looks less native, but supports following the system colour scheme, so LOOT's light and dark themes can be more consistent in style.

Compared to the windows11 style, the Fusion style is more consistent across GUI components and between light and dark colour schemes, but it doesn't attempt to look anything like a native Windows (11 or otherwise) GUI.

The Fusion style is also available on Linux and is used by default on GNOME (KDE uses its Breeze theme instead).

The only issue with the Fusion style that I've noticed so far is that on Windows it overuses the system's accent colour, which can lead to poor readability when selecting or hovering over interactive elements. Strangely, it also uses the system's accent colour as the background colour for checkboxes (whether they're checked or not), but only in the dark colour scheme. I can override the checkbox styling, though it's a little awkward.

Screenshots

Main window

windowsvista with default theme

Fusion with light colour scheme

windowsvista with dark theme

Fusion with dark colour scheme

Although the hyperlink text is too dark here, that's because LOOT isn't aware that the dark colour scheme is being used and is overriding the hyperlink text colour incorrectly - if I remove the override the style's default colour has good contrast.

Groups editor

windowsvista with default theme

Fusion with light colour scheme

windowsvista with dark theme

Fusion with dark colour scheme

Fusion accent colour use

Light colour scheme

Dark colour scheme