How to edit themes in Linux Mint Cinnamon - Tutorial

Updated: November 14, 2018

I came across an interesting, frustrating problem while testing Linux Mint 19 Tara. Namely, the Cinnamon edition of this distro uses the new flat Mint-Y theme. While pretty, it's also ergonomically bad. It comes with a low font contrast (pale gray on white), making it very hard to distinguish elements or spend any spell of time reading. I wanted to fix this right away, and I realized the solution wasn't trivial.

Similar to what I've shown you in my Gnome theme editing tutorial, I'd like to give you a very similar take on Cinnamon. This will not be a very long guide, but it should save you a lot of trouble. If you want to use this desktop environment, and you find the existing theme/font color choices are inadequate, follow me.

Teaser

Gnome = Cinnamon

Whenever this kind of comparison is brought up, it provokes ungodly wrath in the community. People are quick to point that while based and forked off Gnome 3 in the past, Cinnamon is NOT Gnome 3. Well, whatever the technical reasoning is, under the hood, there are a lot of similarities between the two, including theme management.

In Gnome, as I've shown you in the tutorial above, you can change themes using Gnome Tweak Tool. Furthermore, you have the option to manually edit themes. Go to either /usr/share/themes or ~/.themes, and then in the relevant theme folder, edit the gtk-3.0/gtk.css file. By edit, I mean you need to change CSS classes and their attributes, like the font color.

In Cinnamon, the basic principles are the same. But there are also some small differences. Normally, under each theme folder, you will find the following sub-folders:

Theme contents

In other words, the themes are still very much like Gnome 3, with some overrides and extras that are specific to Cinnamon. But in essence, most of the theme changes are almost identical to what we've already seen. This is good. Makes our work simpler.

Now, in contrast to Gnome, we need to make two changes - cinnamon.css file under the cinnamon folder and gtk.css file under the gtk-3.0 folder. Most of the actual theme items will be under the latter. Now, before that, we need to figure what theme our desktop is actually using.

Indeed, what theme am I using?

This is a good question. Because, before you can edit a theme, you actually need to know which one you're using in your Cinnamon desktop. This is not quite as straightforward as in Gnome - although in Gnome, you don't get a friendly tool that actually lets you change themes by default.

Open Settings > Themes. Focus on the Themes tab. Here, there are several elements. You can control windows borders separately from the main theme (more like Gnome 2 and MATE). The section that reads Control is actually your main theme. This may sound counterintuitive, but borders + controls = theme. By default, both should be Mint-Y in Mint 19 Cinnamon, so that's the folder you need to access and then change the CSS files.

Theme

Ignore the specific look & feel of the menu above - the important thing is to know what to look for.

Edit CSS files

All right. Like Gnome, we're looking for the font color declaration. In CSS terms, color: #ABCDEF. Mint-Y uses #4a4a4a for text color. We will do a bulk search & replace in both cinnamon.css and gtk.css. Please back these files up first please! A common piece of the actual CSS styles will be something like:

min-height: 20px;
padding: 5px 32px;
transition-duration: 0;
color: #4a4a4a;
background-color: whitesmoke;
border: 1px solid #d9d9d9;

We want to replace #4a4a4a to #000000 (black). Once you've done this, log out then log back in - for me, switching between themes or even restarting Cinnamon was not sufficient. Once you log into a new session, you should see the theme changes, including ergonomically superior font contrast:

System settings, new fonts, legible now

Black fonts, better

Conclusion

And there we go, job done! In essence, this is easy but also not trivial. Working with CSS files on the command line, making changes that may require sudo permissions just to have a somewhat altered desktop theme, well that's not what I call progress. How many ordinary people feel comfortable playing with the strange lingo that are CSS directives? And why should they ever need to do that? Why not have a GUI option?

Then, Cinnamon ups the complexity game with two CSS sources - not just one, so bear that in mind. Finally, like Gnome, your changes may get overwritten come the next update, so have backups in place, or better yet, create your own themes. Copy the Mint-Y folder and call it Mint-YY or something - and edit the index.theme file to include your own description and name. Anyway, I wish things were simpler, default font ergonomics better, and theme changes unnecessary, or rather, much easier to implement. Failing that, you have this little guide to help you achieve the necessary comfort. See you around.

Cheers.

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