How to manage fonts weight and links

Hi,

I’m pretty new in WP, I’m working on a site with a page builder, Elementor Pro (my customer choose it, don’t blame on me).
I’ve installed Twenty Seventeen and I need to change some attributes for links to be used in body text.
I would like to have a fixed color for the active link with a thinner underline, and a different color for the hover effects always with the same underline.

I chose Exo as the font family, and in the site I use a thin weight, 200 or 300 depending on the sections.
But when I need to make a text bold it change the weight sooo much, I would like to have less difference (i.e. normal text 200, bold 400).
Is it possible to do that? How can I apply these changes?

Thank you in advance for your help, I don’t know anymore where to bang my head…

Bye!

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