Cool! Not fond of the colors but love tree view.
The colors help me track what level of indentation I'm on, but you could get rid of them by editing the script file. See my post 45 on where the file will be located (for Firefox). In Chrome it may be:
C:\Users\Dan\AppData\Local\Google\Chrome\User Data\Default\Extensions\gojeondackiacclkpkfkcglebgncddof\1.0\script.js
Bold is the part that might change for you, and that's on Vista/Win7.
From there, open it up and on line 32, you'll see:
const BACKGROUNDS = ['#ccf', '#ffc', '#cfc', '#fcc', '#cff', '#fcf', '#ccc'];
If you change all of the "#XXX" (or whatever)s to #fff, it should disable the colors for the posts.