1. Go to C:\Program Files (x86)\Steam\resource\styles (Basically your steam directory, wherever it is) 2. Open steam.styles with notepad. (You get the idea, something to edit text with) 3. Press Ctrl + F and type in searchword "friends_chat_text" 4. Change every "font-size=16" to "font-size=14" until you get to "Chat_MenuButton_withChrome". Credit goes to Bramble for figuring this out before me.
Yeah, they changed it into some bigger size for the existing font which for me looks like shit after using steam for 6-7 years.