Steam – How to change font settings in steam for Main Category text

Since some time now, Steam has built in support for adding a nickname to a friend. Note that this doesn't change a nickname, but rather adds one to your friend's name in parentheses. It works like this:

First, right-click on your friend's name:

Second, choose a nickname:

Result is a nickname behind your friend's current alias:

You can edit the Steam UI's style files to change font sizes. The files steam.styles and gameoverlay.styles control the look-and-feel of the Steam UI and the overlay UI, respectively. You can locate these by navigating to your Steam folder (usually under Program Files) and navigating into the resource then styles folders.

By finding the lines that contain font-size=, you can change the font size of any UI element.

Specifically, to change the chat font size, find the code blocks that look like this:

friends_chat_text
{
textcolor="text"
selectedtextcolor="TextentrySelected"
SelectedBgColor="focus"
font-size=20
}

And change the font-size to 14 or whatever is comfortable. There are multiple UI types used in Steam Chat, so you will want to inspect and maybe change the font-size in multiple code blocks. The names of the code blocks that are relevant are:

• friends_chat_text
• friends_chat_text_self
• friends_chat_event
• friends_chat_bright_event
• friends_chat_url
• friends_chat_name_ingame
• friends_chat_self
• friends_chat_name
• friends_chat_accountid
• friends_chat_securitylink

You'll have to restart Steam to see the changes.

Be aware that changing these lines is changing the core Steam files, so they'll probably be overwritten when Steam updates. To make these changes stick (and be easier to remove), you might want to look into how to make a Steam skin, and keep your changes in that. (The downside of creating a Steam skin is then you face maintaining it if an update breaks it.)