In my experience, the default font size appears to be 14.
I have changed all of the values you show to 18 (large enough), but I notice there are still some bugs.
-For example, if you post a link and then keep typing after it, the text after goes back to default.
-Also, the entry box is still default size
-Lastly, the friends' list is still default size
I tried changing EVERY
font-size to 18, and that causes menus to break, so I decided to pick and choose through...
Open friendpanel.layout in notepad...
Change font-size under namestyle and nameInstanceStyle to increase the font size of the person's name
Change font-size under statusStyle to increase the font size of the person's status / game
Open steam.styles in notepad...
Change font-size under TextEntry to increase the font size of the entry box in chat
Change font-size under ListPanel to stop it from changing font size after posting a link.
It should also be noted that every time steam updates, it will erase your changes.
To avoid this, make a new folder inside of Skins (named whatever you want), copy into it the ..\\Steam\\Graphics folder, and the ..\\Steam\
esources folder. Edit the files mentioned by Lampen and I in this new skin folder, then tell it to change skins.
It should never override you again!
For those curious, here is what mine looked like once I was done (I started with "Invert" by 2SeeKU
, but you could do the changes with the standard theme too as I described above): Friends list, chat, and Steam window