The SASS library supports the usage of two different syntaxes, the indented .sass and the curly brace-delimited .scss. Currently we use both .scss and .sass files in src/sass. Using both syntaxes can be confusing and I think we should unify to using only one of them.

Doing a quick check of the amount of code we have of each:

find . -name '*.scss' | xargs wc -l
  567 ./vendors/_include-media.scss
  220 ./abstract/_members.scss
   72 ./abstract/_variables.scss
  793 ./_legacy/_phylo.scss
   68 ./_legacy/_annotation.scss
   39 ./base/_typography.scss
  120 ./base/_form.scss
   41 ./base/_bootstrap.scss
   33 ./base/_placeholder.scss
  421 ./base/_utilities.scss
   10 ./base/_layout.scss
   24 ./base/_nav.scss
   52 ./base/_animations.scss
   21 ./base/_general.scss
   37 ./base/_reset.scss
   28 ./fork-awesome.scss
    3 ./components/_loading_spinner.scss
  559 ./components/_grouped.scss
   73 ./themes/default.scss
  382 ./themes/darkster.scss
   81 ./themes/_base.scss
   81 ./themes/greyson.scss
   78 ./themes/monotony.scss
   77 ./themes/herbie.scss
   28 ./themes/_abstract.scss
    8 ./modules/_form.scss
   39 ./modules/_annotation.scss
    4 ./modules/_tree.scss
   90 ./modules/_layout.scss
 4049 total

find . -name '*.sass' | xargs wc -l
    4 ./_modules.sass
    2 ./_abstract.sass
  435 ./_legacy/_graph.sass
   78 ./_legacy/_corpus.sass
  729 ./_legacy/_tree.sass
   84 ./_legacy/_document.sass
  322 ./_legacy/_styles.sass
   15 ./_legacy/_breadcrumb.sass
  141 ./_legacy/_login.sass
   96 ./_legacy/_code_editor.sass
  341 ./_legacy/_list.sass
   12 ./_legacy/_search.sass
    5 ./_legacy/_frame.sass
   11 ./_legacy/_annuaire.sass
   74 ./_legacy/_folder.sass
  123 ./_legacy/_menu.sass
   15 ./_legacy.sass
  187 ./base/_range_slider.sass
    2 ./_components.sass
   11 ./_base.sass
 2687 total

shows we currently have more code in the .scss format, therefore it might make sense to unify to that one.