How do I override React-Selects native styles with my own?

I am new to React and not quite sure how some plugins/components handle CSS.

I am aware of how to use the styleNames prop with the React Select component. However, I want to use it to inject existing utility classes from my site’s existing .css file. I can do this, as per below, but this adds my classes alongside React Select’s default classes and React Select’s default classes override mine.

For example, if I set singleValue color class to be my .color-primary utility class, as such:

<Select 
      onChange={(selectedOption) => onChange({ name: name, value: selectedOption.value }, true)}
      options={options}
      classNames={{
        singleValue: () => 'color-primary',
      }}
      name={name}
    />

The HTML I get for that element is:

<div class="color-primary css-1dimb5e-singleValue">Option 1</div>

Which is fine, but the color specified in .css-1dimb5e-singleValue, which seems to come from a <style> tag injected at the bottom of <head> overrides the color specified in .color-primary which appears in my normal .css file higher up in the <head>.

I know I could use specificity (eg .my-select .color-primary) or create my own SCSS file for my component, but I’d rather just use my existing utility classes already in the site for now.

Would anyone know of a way around this?