History: Improving the Tiki Bootstrap SCSS File Arrangement

For a while, it's been apparent that some variables specified in the themes' -+variables.scss+- file aren't being used, they aren't replacing the default Bootstrap values. It's been necessary to add CSS rules for the theme to implement the desired styles. 

The upgrade from Bootstrap 4 to 5 seemed like a good time to revisit this, and a good time to have another look at the Bootstrap documentation ([https://getbootstrap.com/docs/5.0/customize/sass/]). In the info from the doc page below, Option B  is the sequence of imports similar to what's used by Tiki:

{CODE(caption="Bootstrap importing diagram" colors="css")}
// Custom.scss
// Option A: Include all of Bootstrap

// Include any default variable overrides here (though functions won't be available)

@import "../node_modules/bootstrap/scss/bootstrap";

// Then add additional custom code here

// Custom.scss
// Option B: Include parts of Bootstrap

// 1. Include functions first (so you can manipulate colors, SVGs, calc, etc)
@import "../node_modules/bootstrap/scss/functions";

// 2. Include any default variable overrides here

// 3. Include remainder of required Bootstrap stylesheets
@import "../node_modules/bootstrap/scss/variables";
@import "../node_modules/bootstrap/scss/mixins";

// 4. Include any optional Bootstrap components as you like
@import "../node_modules/bootstrap/scss/root";
@import "../node_modules/bootstrap/scss/reboot";
@import "../node_modules/bootstrap/scss/type";
@import "../node_modules/bootstrap/scss/images";
@import "../node_modules/bootstrap/scss/containers";
@import "../node_modules/bootstrap/scss/grid";

// 5. Add additional custom code here
{CODE} 

It seems Tiki's organization of the files doesn't match this arrangement as well as it might, so some time was spent looking for and testing a way that gets better results. 

!!! Master branch, as of July 2022
For background, here's a typical "theme.scss" file (tikinewt in this case):

{CODE(caption="tikinewt.scss" colors="css")}
//  tikinewt/scss/tikinewt.scss; compile to make
/*  The TikiNewt theme style sheet for Tiki Wiki CMS Groupware. */

@import url("//fonts.googleapis.com/css?family=Simonetta");

@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/functions";
@import "variables"; // Needs to come first, to override Bootstrap defaults.
@import "../../base_files/scss/_tiki-variables.scss"; // Values/definitions for Tiki variables (outside of Bootstrap variables) such as _tiki-selectors.scss.
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/bootstrap.scss";

@import "variables"; // Imported again, to override base_files/tiki-variables defaults, if the theme overrides any (this is a kludge that's another reason to revise the method)

@import "../../base_files/scss/_tiki-selectors.scss";
@import "_tiki-selectors.scss";
@import "../../base_files/scss/_external-scripts.scss";
@import "../../base_files/scss/_select2-tiki_colors.scss";
{CODE}

So -+functions.scss+- needs to come first. Then we've been importing the theme's variables file, then the global Tiki variables, and then (simplified path) vendor/bootstrap/bootstrap.scss, which looks like this:

{CODE(caption="bootstrap.scss" colors="css")}
@import "mixins/banner";
@include bsBanner("");

// scss-docs-start import-stack
// Configuration
@import "functions";
@import "variables";
@import "maps";a
@import "mixins";
@import "utilities";

// Layout & components
@import "root";
@import "reboot";
@import "type";
@import "images";
@import "containers";
@import "grid";
@import "tables";
@import "forms";
@import "buttons";
@import "transitions";
@import "dropdown";
@import "button-group";
@import "nav";
@import "navbar";
@import "card";
@import "accordion";
@import "breadcrumb";
@import "pagination";
@import "badge";
@import "alert";
@import "progress";
@import "list-group";
@import "close";
@import "toasts";
@import "modal";
@import "tooltip";
@import "popover";
@import "carousel";
@import "spinners";
@import "offcanvas";
@import "placeholders";

// Helpers
@import "helpers";

// Utilities
@import "utilities/api";
// scss-docs-end import-stack
{CODE} 

And then the other necessary files are imported. This arrangement  has been working, ''generally'', but, as mentioned, not all variables defined by the theme have been reflected in the final CSS. 

!! Testing and improved performance
To more closely follow the pattern shown on the Bootstrap customize page, in a test installation, the vendor -+bootstrap.scss+- file was copied to Tiki's -+themes/base_files/scss+- and then split  into two files -- -+tiki-bootstrap_functions.scss+- and -+tiki-bootstrap_layout_and_components.scss+- --  that could be imported separately, with the Tiki global and theme variables in between those imports. The import paths of course are updated to point from themes/tiki_base to the vendor Bootstrap directory. The original vendor bootstrap.scss is no longer used by Tiki. The vendor/bootstrap/variables.scss file is no longer imported by vendor/bootstrap/bootstrap.scss, but rather directly by the Tiki theme SCSS file.

{CODE(caption="tiki-bootstrap_functions.scss" colors="css")}
// This is a copy of vendor_bundled/vendor/twbs/bootstrap/scss/_bootstrap.scss containing only the top lines of the file 
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/mixins/banner";
@include bsBanner("");


// scss-docs-start import-stack
// Configuration
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/functions";
{CODE}

{CODE(caption="tiki-bootstrap_layout_and_components.scss" colors="css")}
// This is a copy of vendor_bundled/vendor/twbs/bootstrap/scss/_bootstrap.scss with lines now in tiki-bootstrap_functions.scss and the default variables import statement commented out
//@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/mixins/banner"; -- now in _tiki-bootstrap_functions
//@include bsBanner("");


// scss-docs-start import-stack
// // Configuration
// @import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/functions"; -- now in _tiki-bootstrap_function
//@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/variables"; -- now imported by themename/scss/themename.scss
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/maps";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/mixins";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/utilities";

// Layout & components
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/root";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/reboot";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/type";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/images";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/containers";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/grid";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/tables";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/forms";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/buttons";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/transitions";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/dropdown";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/button-group";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/nav";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/navbar";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/card";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/accordion";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/breadcrumb";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/pagination";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/badge";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/alert";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/progress";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/list-group";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/close";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/toasts";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/modal";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/tooltip";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/popover";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/carousel";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/spinners";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/offcanvas";
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/placeholders";

// Helpers
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/helpers";

// Utilities
@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/utilities/api";
// scss-docs-end import-stack

@import "../../../vendor_bundled/vendor/twbs/bootstrap/scss/nav";
{CODE}

This worked for most of the variables tried so far, but initially it didn't work  for -+$nav-item-color+-. The color indicated by the Bootstrap CSS variable persists even when theme SCSS compiling tries to override it, and even when the CSS variable is replaced by a hex color code in the vendor Bootstrap variables file (this was checked to rule out the use of CSS variables as a factor). 

Finally it was found that if the -+vendor/bootstrap/nav+- file is imported directly in (near the bottom of) the -+theme.scss+- file OR if  the -+nav+- import statement in -+tiki_base/bootstrap-layout_and_components+- is moved to the last import statement position, then the theme's -+$nav-item-color+- is used.

Here's an example of a theme.scss file with the revised import statements:

{CODE(caption="ohia.scss" colors="css")}
//  ohia/scss/ohia.scss: compile to make
/*  The Ohia theme stylesheet for Tiki Wiki CMS Groupware. */

@import url(https://fonts.bunny.net/css?family=alegreya-sans:400,400i|alegreya-sans-sc:400,400i,700);

@import "../../base_files/scss/_tiki-bootstrap_functions";  // The first part of the former bootstrap.scss

@import "variables"; // Needs to come first, to override Bootstrap defaults.
@import "../../base_files/scss/_tiki-variables.scss"; // Values/definitions for Tiki variables (outside of Bootstrap variables) such as _tiki-selectors.scss.
@import "../../default/scss/variables"; // Provide any variables not defined by theme or tiki_base

@import "../../base_files/scss/_tiki-bootstrap_layout_and_components"; // The last part of the former boostrap.scss

@import "../../base_files/scss/_tiki-selectors.scss";
@import "_tiki-selectors.scss";
@import "../../base_files/scss/_external-scripts.scss";
@import "../../base_files/scss/_select2-tiki_colors.scss"; // This should probably be imported by _external-scripts.scss
{CODE}

Because -+nav+- is one of the "optional" Bootstrap component files, presumably where it comes in the sequence of imports doesn't matter, so maybe there's no downside to moving -+nav+- like this. There's no indication so far that other variables are impacted by the move.

A downside of this reorganization is that there is a small amount of redundancy involved in the vendor bootstrap,scss file being copied and split in themes/base_files/, but this file won't change much, if at all, except possibly in major upgrades, so there isn't much of a maintenance hit. And if it works better for themes, then it's worth it.