Rewrite Theming docs as Customize section

- Broke up existing theming page into separate pages
- Audited and updated each new docs page (some pages include some TBD sections)
- Update sidenav to reflect changes
- Fix links that pointed to the old Theming page
- Update docs styles to reflect recent changes
- Rewrite some bits in the Migration page

1 files changed, 1 insertions, 1 deletions

diff --git a/site/content/docs/4.3/getting-started/webpack.md b/site/content/docs/4.3/getting-started/webpack.md
index f170c1a4d..10e536bbf 100644
--- a/site/content/docs/4.3/getting-started/webpack.md
+++ b/site/content/docs/4.3/getting-started/webpack.md
@@ -35,7 +35,7 @@ This means that you will have to make sure to add both of them to your `package.
 
 To enjoy the full potential of Bootstrap and customize it to your needs, use the source files as a part of your project's bundling process.
 
-First, create your own `_custom.scss` and use it to override the [built-in custom variables]({{< docsref "/getting-started/theming" >}}). Then, use your main Sass file to import your custom variables, followed by Bootstrap:
+First, create your own `_custom.scss` and use it to override the [built-in custom variables]({{< docsref "/customize/sass" >}}). Then, use your main Sass file to import your custom variables, followed by Bootstrap:
 
 {{< highlight scss >}}
 @import "custom";