The following is an unofficial and simplified guide to get started on custom Steam Skins(btw I use vim).
-Copy the "steam.styles" file from /resource/styles ((in Linux it's under /home/username/.steam/resource/styles/ )) to your pre-existing "skins" folder
-Make new folders as need to create the path "/skins/SomeSkin/resource/styles/" where "SomeSkin" is your chosen name for the custom skin.
-Move the "steam.styles" file to /skins/..../styles/
-Rename it to avoid confusion. Try SomeSkin.styles .
-Make a copy to fallback to in case you mess up. Call it SomeSkin.styles.bak ***To use the backup, delete the edit SomeSkin- then make a copy of the .bak as "SomeSkin.styles". In Linux ( rm SomeSkin.styles && cp SomeSkin.styles.bak SomeSkin.styles ).
-open SomeSkin.styles in your text editor of choice(btw i use vim) -Find the entry 'Text="' which should be about the 7th paragraph or line 58 -change the numbers in between the " " to a color(blue); -do the same for "TextGlowHover" and "TextGlowSelected" -save file and close
-Shutdown Steam completely. In Linux, you can type in your terminal "sudo pkill -9000 steam"
-Relaunch steam
-At the top-left, go to "Steam" > "Settings" > "Interface"(above Downloads)
-Click on the third drop-list from the top, under "Select the skin you wish Steam to use (requires Steam to restart)"
-Move mouse down to desired skin and click "Ok" and repeat Steps 1,2.
-Restart Steam in Developer Mode. In Linux, type "steam -dev"
-Go to a page you would like to see edited. -Hit "F6" to open a window called "vgui layout debugger"
-Examine the code and take note of its properties.
-Go back to your style file; having made a backup of your already-working style, continue to modify it as desired.
-Save style; Close steam; relaunch;