update theme/README.md

.gitignore

@@ -1,4 +1,5 @@
 dist
 ./*/staging
 node_modules
-./*/.storybook-out
+./*/.storybook-out
+.DS_Store

theme/README.md

@@ -4,4 +4,28 @@ ImmuneSpace theme and styles shared between React modules.
 
 1. Creates `core.css` which can be loaded into ImmuneSpace via the UI. 
 2. Defines variables, functions, and mixins which can be used in immunespace 
-to enable consistent styling. 
+to enable consistent styling. 
+
+## Updating site-wide styles for ImmuneSpace
+
+1. Build dev version of this package  
+    1. `npm install`
+    1. `npm run build`
+    1. This will create `immunespaceFrontendTools/theme/dist/core.css`. 
+1. Go to look and feel settings resources in ImmuneSpace: https://www.immunespace.org/admin/adminConsoleResources.view?
+1. Upload `immunespaceFrontendTools/theme/dist/core.css` as a custom stylesheet. 
+
+## Loading sass variables 
+ImmuneSpace theme variables are declared in `_immunespace.scss`. When the package is built, this file is copied into the `dist/` directory. To use these variables in an ImmuneSpace React module or in `@immunespace/components`:  
+
+1. `@immunespace/theme` is already installed at the top level of the `LabKeyModules` repo, so you do not need to install it. 
+1. Import the variables into an scss file: 
+    ```scss
+    @use "~@immunespace/theme/dist/immunespace";
+    ```
+1. Use the variables in your scss. 
+    ```scss
+    .module-button {
+        background-color: immunespace.$highlight-primary;
+    }
+    ```