diff --git a/.changeset/pretty-pumpkins-work.md b/.changeset/pretty-pumpkins-work.md
new file mode 100644
index 0000000000..40d19f5cd6
--- /dev/null
+++ b/.changeset/pretty-pumpkins-work.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes an issue that was breaking asset and stylesheet URLs when building for a subpath
diff --git a/packages/astro/src/core/build/static-build.ts b/packages/astro/src/core/build/static-build.ts
index 2884174f46..6150dd9954 100644
--- a/packages/astro/src/core/build/static-build.ts
+++ b/packages/astro/src/core/build/static-build.ts
@@ -162,7 +162,7 @@ async function ssrBuild(opts: StaticBuildOptions, internals: BuildInternals, inp
 		root: viteConfig.root,
 		envPrefix: 'PUBLIC_',
 		server: viteConfig.server,
-		base: astroConfig.site ? new URL(astroConfig.site).pathname : '/',
+		base: astroConfig.base,
 		ssr: viteConfig.ssr,
 		resolve: viteConfig.resolve,
 	} as ViteConfigWithSSR;
diff --git a/packages/astro/src/core/config.ts b/packages/astro/src/core/config.ts
index 74942e56ff..8b16ce5a0a 100644
--- a/packages/astro/src/core/config.ts
+++ b/packages/astro/src/core/config.ts
@@ -14,7 +14,7 @@ import load, { resolve, ProloadError } from '@proload/core';
 import loadTypeScript from '@proload/plugin-tsm';
 import postcssrc from 'postcss-load-config';
 import { arraify, isObject } from './util.js';
-import { appendForwardSlash, trimSlashes } from './path.js';
+import { appendForwardSlash, prependForwardSlash, trimSlashes } from './path.js';
 
 load.use([loadTypeScript]);
 
@@ -95,7 +95,7 @@ export const AstroConfigSchema = z.object({
 		.string()
 		.optional()
 		.default('/')
-		.transform((val) => appendForwardSlash(trimSlashes(val))),
+		.transform((val) => prependForwardSlash(appendForwardSlash(trimSlashes(val)))),
 	trailingSlash: z
 		.union([z.literal('always'), z.literal('never'), z.literal('ignore')])
 		.optional()
diff --git a/packages/astro/test/static-build.test.js b/packages/astro/test/static-build.test.js
index a461209a20..ce470b2b6c 100644
--- a/packages/astro/test/static-build.test.js
+++ b/packages/astro/test/static-build.test.js
@@ -96,6 +96,9 @@ describe('Static build', () => {
 			for (const link of links) {
 				const href = $(link).attr('href');
 
+				// The imported .scss file should include the base subpath in the href
+				expect(href.startsWith('/subpath/')).to.be.true;
+
 				/**
 				 * The link should be built with the config's `base` included
 				 * as a subpath.