As we use CSS variables for main colors, font and sizes, you can just reset the needed values. And they will be applied throughout the app:
<style>
.demo-box{
--wx-color-primary: #b4005a;
--wx-color-secondary: #d3e2d7;
--wx-font-size: 16px;
--wx-switch-width: 55px;
}
</style>