This theme is for those who find red To-Dos stressful enough that they're discouraged from doing them. This neatly solves the problem -- your oldest To-Dos are now a nice, inviting blue.
Disclaimer: It's not elegant---the colors are just hardcoded and it's got !important all over the place. It will almost certainly break with any significant change to the website, but the developer will try to get it fixed soon-ish if that happens.
Before installing this user style, make sure you have one of the following installed:
- Stylish (Firefox, Chrome, Safari or Opera)
- A user script manager (Greasemonkey for Firefox or Tampermonkey for Chrome, Dolphin Browser, Firefox, Opera Next, Safari, and UC Browser).
Then, navigate to the website for this user style. Stylish users can load this style with one click using the green "Install with Stylish" button. Greasemonkey or Tampermonkey users can load this style with the "install this style as a user script" link in the blue box.
If the style has options, you should select the ones you want before installing it. On the userstyles.org website, you can do that by clicking the "Advanced Style Settings" button. To change your choice of options, delete the style and reinstall it.
After the style is loaded, you may need to refresh the page to see its effects. The style can be easily turned off and on with a handy checkbox that you can find by clicking the Stylish/Greasemonkey/Tampermonkey icon in your toolbar.