Custom CSS for font weight not working

Site url: https://onion-mouse-9rsa.squarespace.com/

Password: awaken

Hi All, 

I'm trying to adjust the bold font weight for paragraph text.  I'm using a preloaded font (proxima nova) and I've checked to make sure the font weight I'm using in the CSS is available (it is 🙂)

If I adjust the weight of the regular font the code seems to work but as soon as I refresh the page it goes back to the heavier weight 

The code I'm using is : 

p strong
{
font-weight: 600 !important;
}

This is a screenshot of the code applied

And this is what it keeps reverting to 

Do I need to load the font with this specific weight somewhere on the site?

Any ideas would be much appreciated 

Thank you!

Which page in your screenshot?

Hey @tuanphan

Thanks for the reply! I ended uploading the font as a separate file 🙂