Basic themes are presets that come with Nuclear. You'll find them in Preferences → Themes as clickable buttons. They adjust the app's core colors, backgrounds, and text contrast. You can't create your own basic themes.
Advanced themes
Advanced themes give you complete creative control through JSON files. You can customize everything from colors and accents to fonts, corner radii, borders, and shadows. They work in both light and dark modes, and you can see your changes live as you edit. Just drop your JSON files in the themes folder and pick them from the Advanced themes dropdown. See Advanced themes for more details.
