Customizing a Doom Emacs Theme

Published on 2nd December 2022 Approx 2 minutes read

Creating your theme/modifying an existing one, or overriding some faces (globally) in Emacs, especially Doom Emacs is really easy once you understand how to do it… but it wasn’t very easy to understand how to do it. Most likely I was doing something wrong, or maybe it’s just because I don’t fully know how lisp or emacs works that’s why it took me long but I spent a good part of my evening trying to make even small changes to work.

So, I have created this short tutorial to leave me (and others having problems) some notes on how to modify a Doom Emacs theme. I’m using Doom Emacs which comes with the doom-themes packages doing some basic setup so we only need to define some variables and it automatically applies other faces and stuff, and I’m pretty sure doom-themes can be installed on regular Emacs.

Overriding faces

Each element in an emacs buffer has a “face” which defines its foreground/background color, font styling, etc. You can do M-x RET describe-char or describe-face to get the face of the area under the cursor, or to get a list of all the available faces (which is very long)

The custom-set-faces! macro (or custom-set-faces for Emacs users) can be used to customize any face:

(custom-set-faces!
  '(default :background "#100b13")
  '(cursor :background "#0ec685" :foreground)
  '(line-number :slant normal :background "#100b13")
  '(line-number-current-line :slant normal :background "#21242b"))

You can add something like this to your ~/.doom.d/config.el

Using a doom theme as a template

Another way to modify your Doom theme is to use an existing theme as a template (or, starting from bottom up!) and modifying it.

How to modify an existing theme:

Go to this page and choose any theme you like, and download the raw file into ~/.doom.d/themes/<theme-name>-theme.el. The theme name can be anything, but make sure it ends with “-theme.el” or Doom won’t recognise it as a theme.
Open the theme in your favourite text editor (I wonder which one it is) and edit the line that says (def-doom-theme <theme-name> and replace <theme-name> with any name you like, make sure not to use the original name (or the name of any other theme that already exists on your system) or it would create a clash. Now, edit the theme to your liking and you’re good to go!
Open a new Doom Emacs frame and enter SPC h t t and select your new theme!