JetBrains Mono font settings

Question

I have been trying to configure emacs to use JetBrains Mono font, unfortunately i can hardly understand the way emacs handles font settings, there are way too many options and stuffs going on. So i got lost and here is my current font settings -

(set-face-attribute 'default nil
                    :family "JetBrains Mono"
                    :height 110
                    :weight 'light)
(set-face-attribute 'variable-pitch nil
                    :family "JetBrains Mono"
                    :height 1.0)
(set-face-attribute 'fixed-pitch nil
                    :family "JetBrains Mono"
                    :height 1.0)

But this seems not as per recommended settings from the jetbrains's site -

Size: 13
Line spacing: 1.2

I don't know to relate :height with Size: 13, couldn't figure that out. I also failed to match the line spacing 1.2. If i use (setq line-spacing 1.2) emacs renders lines way too separated vertically.

I am using emacs 27.1 with harfbuzz.

So if anyone has been using this font with emacs, please share your configuration or point me to some place where i can get/understand how to configure and match the recommended settings.

Thanks in advance.

Answer 1

Here is a snippet from my custom.el:

 '(default-frame-alist
    '((fullscreen . fullscreen)
      (font . "JetBrains Mono-13")
      (line-spacing . 0.2)))

The JetBrains website doesn't specify the unit for their recommendation of "13", but inspecting the CSS reveals that their examples have a CSS font-size of 13px.

Emacs documentation on fonts specifies that the sizes point sizes.^[1]

Emacs on my macOS machine reports the value of display-pixels-per-inch as "72" whereas CSS specifies that a pixel is 1/96th of 1 inch.^[2] Nevertheless, the value of 13 points in Emacs seems to be the same height in real display pixels as the 13 pixels on the JetBrains website in Chrome and Firefox and I can't understand why that would be.

The line-spacing property is set as a height spec and refers to the amount of space added below each line. Therefore, you only want the extra space more than a default, single line height. The value should be 0.2.