1. Let's generate the code for fluid fonts.
First we need to generate the code for our purpose. For that you will find one really usefull generator I use here at https://utopia.fyi/generator-mk-ii/
Ajust it according to your needs.
Then select 'USE CLAMP' and copy the generated code. We are going to use the created variables in Oxygen settings.
2. Adding the code in Oxygen builder.
Select your stylesheet or create one.
And paste the code in your ':root' selector.
3. Lets make it work globally.
Then select 'Body Text'.
Enter the corresponding variable for the body text font size. I personnaly choose to name my variables font 'fs' for 'font scale' but name it as you want or leave them as given by the generator.
Do the same for the headings and you're done...
4. Final result
As simple as that. Beautiful and efficient result for the entire site done in 3 easy steps.
Nothing transcendental of course, but no more need to think about it, everything is under automatic control, in total fluidity and without breakpoints.