How to properly work with font-sizes in Sketch (pt to px)?

Question

Design

I'm laying out the layout, I met text with a size of 5px - 7px . I tell the designer: "Your font sizes are too small here, you can barely see them, you should increase them", to which I get the answer: "dude, these are not pixels (px), but points (pt)". Started googling.
Found:

1. Yes the sketch uses pt instead of px for font sizes
   
2. Found a bunch of calculators that convert you pt to px
   
3. It is better not to use it for layout, as the results may vary from browser to browser.
   

I start testing.
I set the value 5pt - 7pt , I look in the browser all the rules, this is another matter. Then I try to convert all font-size to pt . And then the layout starts to fly into the trash.

The screenshot above is font-size: 15px for the texts.

The screenshot above is font-size: 15pt for the texts.

Answer 1

Interesting.
Created a block of text, size - 14 (something).
Right click - Copy CSS Attributes. I also get font-size: 14px.
And I have the layout at my fingertips, I'm typing from it, similarly to the 14px text.
If I used the formula about 1px = 0.75pt ( https://stackoverflow.com/questions/44730718/sketc... ), then it should be 19px.
I export the layout to jpg, take the PixelPerfect extension, apply the layout to the layout.
No, it's clearly 14px.
Use the same method, you will understand what font-size is actually needed. In the end, just adjust by changing in the inspector.