Add the `exports` field for CSS files.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@splidejs/splide",
-  "version": "3.6.14",
+  "version": "4.0.0",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@splidejs/splide",
-      "version": "3.6.14",
+      "version": "4.0.0",
       "license": "MIT",
       "devDependencies": {
         "@babel/core": "^7.16.10",

package.json

@@ -84,5 +84,11 @@
     "src/js/transitions",
     "src/js/types",
     "src/js/utils"
-  ]
+  ],
+  "exports": {
+    ".": "./dist/js/splide.esm.js",
+    "./css": "./dist/css/splide.min.css",
+    "./css/core": "./dist/css/splide-core.min.css",
+    "./css/*": "./dist/css/themes/splide-*.min.css"
+  }
 }