How can I tinker with Libreoffice's default GUI?

I’m on Linux and I use Libreoffice without GNOME/KDE integration. So it looks the most basic way, just as shown in the pic. Can I somehow modify this look but WITHOUT enabling the desktop integration thing? I just want to increase the font size (10 points instead of 8) and maybe adjust some colors, or get rid of those toolbar gradients and make it flat. Do I really need DE integration for things like this? Can’t it be done without that GTK/QT part somehow?

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