The full compiled stylesheet is around 150 kilobytes before compression, and most projects use the grid, some utilities and three components.
// required, in this order
@import "bootstrap/functions";
@import "custom-variables"; // yours, overriding the defaults
@import "bootstrap/variables";
@import "bootstrap/mixins";
// then only what is used
@import "bootstrap/reboot";
@import "bootstrap/grid";
@import "bootstrap/utilities";
@import "bootstrap/buttons";
@import "bootstrap/forms";The order is load-bearing: variables must come after functions and before the Bootstrap variables file, because the defaults are declared !default and only apply if nothing set them already. Getting this wrong produces a build where the custom colours are silently ignored, which is a confusing twenty minutes. On one project this took the stylesheet from 148 KB to 39 KB, which is a real number and mostly came from dropping components nobody had used.