Tailwind / Webpack / Gatsby - CssSyntaxError when compiling Tailwind CSS

Question

I'm using Tailwind on a Gatsby site and this has been compiling fine but just started throwing the following error on develop and build cycles:

ERROR #98123  WEBPACK

Generating development JavaScript bundle failed

File: ..\themes\@mytheme\gatsby-theme-mytheme\src\styles\global.css:1:0

failed Building development bundle - 158.060s
ERROR in ../themes/@mytheme/gatsby-theme-mytheme/src/styles/global.css  
Module build failed (from ../node_modules/mini-css-extract-plugin/dist/loader.js):
ModuleBuildError: Module build failed (from ../node_modules/css-loader/dist/cjs.js):
CssSyntaxError

Module build failed (from ../node_modules/css-loader/dist/cjs.js):
CssSyntaxError

(1:0) C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\themes\@mytheme\gatsby-theme-mytheme\src\styles\<no source> Unclosed bracket     

(1:0) C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\themes\@mytheme\gatsby-theme-mytheme\src\styles\<no source> Unclosed bracket     
    at processResult (C:\LineIndustries - GIT\Clients\Pan Macmillan\www.panmacmillan.com - THEME BUILD\node_modules\webpack\lib\NormalModule.js:758:19)
    at C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\node_modules\webpack\lib\NormalModule.js:860:5
    at C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\node_modules\loader-runner\lib\LoaderRunner.js:400:11
    at C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\node_modules\loader-runner\lib\LoaderRunner.js:252:18
    at context.callback (C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\node_modules\loader-runner\lib\LoaderRunner.js:124:13)
    at Object.loader (C:\FILES- GIT\Clients\Project\www.mysite.com - THEME BUILD\node_modules\css-loader\dist\index.js:155:5)
 @ ../themes/@mytheme/gatsby-theme-mytheme/gatsby-browser.js 5:0-33
 @ ./.cache/api-runner-browser-plugins.js 69:10-91
 @ ./.cache/api-runner-browser.js 4:14-53
 @ ./.cache/app.js 12:0-65 29:87-33:1 37:20-29 50:0-14 116:17-26 150:6-15 29:0-33:2

In my global CSS file I import the Tailwind core CSS in the following way:

@tailwind base;
@tailwind components;
@tailwind utilities;

Removing the line for 'utilities' stops the error but obviously removes half the tailwind core CSS. This would seem to suggest there's a CSS syntax error in the Tailwind core utilities file but I find this hard to believe. This has worked previously and nothing else has changed in the project as far as I'm aware.