seabird

A Vim theme based on hue 202 , a soothing blue of sea and sky. The light version is seagull; the dark, petrel.

Featuring gui (Linux/Windows GVim, MacVim, Neovim), terminal, and true (24-bit) colour support.

screenshots

seagull		petrel

installation

step 1: download the colour scheme

option A: manually

Download seagull.vim and/or petrel.vim from this repository and place in directory ~/.vim/colors/ (Linux/Mac) or %userprofile%\vimfiles\colors\ (Windows).

option B: using a plugin manager

For easy management of Vim colour schemes (and other plugins), try a plugin manager. With the Vundle plugin manager, for instance, just add Plugin 'nightsense/seabird' to the list of plugins in your vimrc, then run VundleUpdate. (To automatically keep plugins up to date with Vundle, add vim +VundleUpdate +qall to a startup script or cron job.)

step 2: activate the colour scheme

Add colorscheme seagull or colorscheme petrel to your vimrc.

Or, if you'd like to switch automatically between them based on time of day, add this block (which activates petrel when launching Vim between 8PM and 8AM, seagull otherwise):

if strftime("%H") < 8 || strftime("%H") > 20
colorscheme petrel
else
colorscheme seagull
endif

step 3: configure terminal colours (if using Vim in a terminal)

In order for seagull or petrel to work properly in terminal Vim, the terminal's colours should be set to match those of the active Vim theme.

As of now, this repository only provides one terminal configuration file: Xresources, which is used by two popular Linux terminals, xterm and urxvt. If you'd like to see a configuration file for another terminal, feel free to make a request.

how seabird took flight

step 1: choose a principal hue

Hue 202 was chosen.

step 2: choose base colours

The base colours were selecting using the hue/saturation/value model of colour definition.

First, all base colours were assigned hue 202.

Second, saturation levels were assigned. The lightest colour, seagrey8, was assigned 0. For the remaining colours, an excerpt of the Fibonacci sequence was applied.

base colour	basic role	hue °	saturation %
seagrey1	regular background (petrel)	202	55
seagrey2	highlighted background (petrel)	202	34
seagrey3	subdued text (petrel)	202	21
seagrey4	regular text (seagull)	202	13
seagrey5	regular text (petrel)	202	8
seagrey6	subdued text (seagull)	202	5
seagrey7	highlighted background (seagull)	202	3
seagrey8	regular background (seagull)	202	0

Third, value levels were assigned. seagrey8 was set to 100% value. The remaining colours were assigned values based on contrast ratios with other base colours.

this colour was assigned...	...this hex...	...due to this contrast ratio*...	...with this colour
seagrey1	0c141a	18½:1	seagrey8
seagrey2	1d262b	1⅕:1	seagrey1
seagrey3	61717a	3:1	seagrey2
seagrey4	6d777d	4½:1	seagrey8
seagrey5	787e82	4½:1	seagrey1
seagrey6	83878a	3:1	seagrey7
seagrey7	e6ebed	1⅕:1	seagrey8
seagrey8	ffffff	-	-

• the 3:1 ratio ensures that subdued text on highlighted background meets the ISO-recommended 'standard minimum' for readable text
• the 4½:1 ratio ensures that regular text on regular background meets the W3C-recommended 'accessible minimum' for readable text

step 3: choose seagull accent colours

Accent colour hues were selected from around the (30°-divided) colour wheel: hue 202 plus seven of its companions.

colour	hue
red	352
orange	22
yellow	52
green	112
teal	172
blue	202
purple	262
pink	322

The aesthetic aim of seagull included a bright, cheerful palette of accent colours. The contrast ratio of each hue was tuned accordingly. Each colour started with 100% value and saturation; contrast was adjusted by either lowering saturation (to lower contrast) or lowering value (to raise it).

While the ISO-recommended 'standard minimum' contrast ratio for readable text is 3:1, this proved too high for most colours, leading to a relaxed minimum of 2⅔. The two exceptions were red and purple (the highest-contrast hues), for which the full 3:1 ratio was applied.

seagull accent colour	hex	contrast ratio*	hue °	saturation %	value %
red	ff596f	3	352	65	100
orange	ff7626	2⅔	22	85	100
yellow	b69e00	2⅔	52	100	71
green	19b500	2⅔	112	100	71
teal	00b098	2⅔	172	100	69
blue	08a5ff	2⅔	202	97	100
purple	ab7aff	3	262	52	100
pink	ff63c7	2⅔	322	61	100

step 4: choose petrel accent colours

The seagull accent colours were converted to the petrel theme by reducing saturation of all hues by ⅓, then adjusting value to achieve 4½:1 contrast ratio* (the W3C-recommended 'accessible minimum' for readable text) with the petrel background.

petrel accent colour	hex	contrast ratio*	hue °	saturation %	value %
red	b56771	4½	352	43	71
orange	ad6f4b	4½	22	57	68
yellow	8a7e2d	4½	52	67	54
green	3b8f2f	4½	112	67	56
teal	2e8c7f	4½	172	67	55
blue	3e85b0	4½	202	65	69
purple	8972b0	4½	262	35	69
pink	ad6694	4½	322	41	68

notes

The seabird colour scheme files are generated by modifying those of the flattened colour scheme by Romain Lafourcade, which is in turn derived from the Solarized colour scheme by Ethan Schnoonover.

Colour adjustment was performed with the GIMP colour selection tool. Contrast ratios were calculated with these formulas.

* minimum contrast; actual contrast may be slightly higher (due to discrete jumps in digital colour values)