diff --git a/src/@types/astro.ts b/src/@types/astro.ts
index 5790c4b78827..8f6b73d5e317 100644
--- a/src/@types/astro.ts
+++ b/src/@types/astro.ts
@@ -33,3 +33,5 @@ export interface CompileResult {
   contents: string;
   css?: string;
 }
+
+export type RuntimeMode = 'development' | 'production';
diff --git a/src/@types/compiler.ts b/src/@types/compiler.ts
index 916242c51961..2f104b5c5022 100644
--- a/src/@types/compiler.ts
+++ b/src/@types/compiler.ts
@@ -1,9 +1,10 @@
 import type { LogOptions } from '../logger';
-import type { AstroConfig, ValidExtensionPlugins } from './astro';
+import type { AstroConfig, RuntimeMode, ValidExtensionPlugins } from './astro';
 
 export interface CompileOptions {
   logging: LogOptions;
   resolve: (p: string) => Promise<string>;
   astroConfig: AstroConfig;
   extensions?: Record<string, ValidExtensionPlugins>;
+  mode: RuntimeMode;
 }
diff --git a/src/@types/optimizer.ts b/src/@types/optimizer.ts
index 22027d2e2a7d..a076ae9b82d8 100644
--- a/src/@types/optimizer.ts
+++ b/src/@types/optimizer.ts
@@ -1,4 +1,5 @@
 import type { TemplateNode } from '../parser/interfaces';
+import type { CompileOptions } from './compiler';
 
 export type VisitorFn = (node: TemplateNode, parent: TemplateNode, type: string, index: number) => void;
 
@@ -14,3 +15,9 @@ export interface Optimizer {
   };
   finalize: () => Promise<void>;
 }
+
+export interface OptimizeOptions {
+  compileOptions: CompileOptions;
+  filename: string;
+  fileID: string;
+}
diff --git a/src/build.ts b/src/build.ts
index 7f4fa713cc00..39b778600abd 100644
--- a/src/build.ts
+++ b/src/build.ts
@@ -1,4 +1,4 @@
-import type { AstroConfig } from './@types/astro';
+import type { AstroConfig, RuntimeMode } from './@types/astro';
 import type { LogOptions } from './logger';
 import type { LoadResult } from './runtime';
 
@@ -60,14 +60,15 @@ export async function build(astroConfig: AstroConfig): Promise<0 | 1> {
     dest: defaultLogDestination,
   };
 
-  const runtime = await createRuntime(astroConfig, { logging: runtimeLogging });
+  const mode: RuntimeMode = 'production';
+  const runtime = await createRuntime(astroConfig, { mode, logging: runtimeLogging });
   const { runtimeConfig } = runtime;
   const { backendSnowpack: snowpack } = runtimeConfig;
   const resolve = (pkgName: string) => snowpack.getUrlForPackage(pkgName);
 
   const imports = new Set<string>();
   const statics = new Set<string>();
-  const collectImportsOptions = { astroConfig, logging, resolve };
+  const collectImportsOptions = { astroConfig, logging, resolve, mode };
 
   for (const pathname of await allPages(pageRoot)) {
     const filepath = new URL(`file://${pathname}`);
diff --git a/src/build/bundle.ts b/src/build/bundle.ts
index 82b6930d5c58..143be0521827 100644
--- a/src/build/bundle.ts
+++ b/src/build/bundle.ts
@@ -1,4 +1,4 @@
-import type { AstroConfig, ValidExtensionPlugins } from '../@types/astro';
+import type { AstroConfig, RuntimeMode, ValidExtensionPlugins } from '../@types/astro';
 import type { ImportDeclaration } from '@babel/types';
 import type { InputOptions, OutputOptions } from 'rollup';
 import type { AstroRuntime } from '../runtime';
@@ -62,9 +62,10 @@ interface CollectDynamic {
   astroConfig: AstroConfig;
   resolve: (s: string) => Promise<string>;
   logging: LogOptions;
+  mode: RuntimeMode;
 }
 
-export async function collectDynamicImports(filename: URL, { astroConfig, logging, resolve }: CollectDynamic) {
+export async function collectDynamicImports(filename: URL, { astroConfig, logging, resolve, mode }: CollectDynamic) {
   const imports = new Set<string>();
 
   // Only astro files
@@ -89,6 +90,7 @@ export async function collectDynamicImports(filename: URL, { astroConfig, loggin
       astroConfig,
       resolve,
       logging,
+      mode,
     },
   });
 
diff --git a/src/compiler/index.ts b/src/compiler/index.ts
index 0ba5657cde95..88ea5caf9deb 100644
--- a/src/compiler/index.ts
+++ b/src/compiler/index.ts
@@ -1,5 +1,5 @@
-import type { LogOptions } from '../logger.js';
-import type { AstroConfig, CompileResult, TransformResult } from '../@types/astro';
+import type { CompileResult, TransformResult } from '../@types/astro';
+import type { CompileOptions } from '../@types/compiler.js';
 
 import path from 'path';
 import micromark from 'micromark';
@@ -13,12 +13,6 @@ import { encodeMarkdown } from '../micromark-encode.js';
 import { optimize } from './optimize/index.js';
 import { codegen } from './codegen.js';
 
-interface CompileOptions {
-  astroConfig: AstroConfig;
-  logging: LogOptions;
-  resolve: (p: string) => Promise<string>;
-}
-
 function internalImport(internalPath: string) {
   return `/_astro_internal/${internalPath}`;
 }
diff --git a/src/compiler/optimize/index.ts b/src/compiler/optimize/index.ts
index e73c93c7c9df..53dd3f2d6b52 100644
--- a/src/compiler/optimize/index.ts
+++ b/src/compiler/optimize/index.ts
@@ -1,6 +1,5 @@
 import type { Ast, TemplateNode } from '../../parser/interfaces';
-import type { CompileOptions } from '../../@types/compiler';
-import type { NodeVisitor, Optimizer, VisitorFn } from '../../@types/optimizer';
+import type { NodeVisitor, OptimizeOptions, Optimizer, VisitorFn } from '../../@types/optimizer';
 
 import { walk } from 'estree-walker';
 
@@ -69,12 +68,6 @@ function walkAstWithVisitors(tmpl: TemplateNode, collection: VisitorCollection)
   });
 }
 
-interface OptimizeOptions {
-  compileOptions: CompileOptions;
-  filename: string;
-  fileID: string;
-}
-
 export async function optimize(ast: Ast, opts: OptimizeOptions) {
   const htmlVisitors = createVisitorCollection();
   const cssVisitors = createVisitorCollection();
diff --git a/src/compiler/optimize/styles.ts b/src/compiler/optimize/styles.ts
index b833f9e7099e..b613e4845961 100644
--- a/src/compiler/optimize/styles.ts
+++ b/src/compiler/optimize/styles.ts
@@ -4,7 +4,8 @@ import autoprefixer from 'autoprefixer';
 import postcss from 'postcss';
 import findUp from 'find-up';
 import sass from 'sass';
-import { Optimizer } from '../../@types/optimizer';
+import { RuntimeMode } from '../../@types/astro';
+import { OptimizeOptions, Optimizer } from '../../@types/optimizer';
 import type { TemplateNode } from '../../parser/interfaces';
 import astroScopedStyles from './postcss-scoped-styles/index.js';
 
@@ -25,9 +26,6 @@ const getStyleType: Map<string, StyleType> = new Map([
   ['text/scss', 'scss'],
 ]);
 
-const SASS_OPTIONS: Partial<sass.Options> = {
-  outputStyle: process.env.NODE_ENV === 'production' ? 'compressed' : undefined,
-};
 /** HTML tags that should never get scoped classes */
 const NEVER_SCOPED_TAGS = new Set<string>(['html', 'head', 'body', 'script', 'style', 'link', 'meta']);
 
@@ -50,8 +48,15 @@ export interface StyleTransformResult {
 // cache node_modules resolutions for each run. saves looking up the same directory over and over again. blown away on exit.
 const nodeModulesMiniCache = new Map<string, string>();
 
+export interface TransformStyleOptions {
+  type?: string;
+  filename: string;
+  scopedClass: string;
+  mode: RuntimeMode;
+}
+
 /** Convert styles to scoped CSS */
-async function transformStyle(code: string, { type, filename, scopedClass }: { type?: string; filename: string; scopedClass: string }): Promise<StyleTransformResult> {
+async function transformStyle(code: string, { type, filename, scopedClass, mode }: TransformStyleOptions): Promise<StyleTransformResult> {
   let styleType: StyleType = 'css'; // important: assume CSS as default
   if (type) {
     styleType = getStyleType.get(type) || styleType;
@@ -80,7 +85,13 @@ async function transformStyle(code: string, { type, filename, scopedClass }: { t
     }
     case 'sass':
     case 'scss': {
-      css = sass.renderSync({ ...SASS_OPTIONS, data: code, includePaths }).css.toString('utf8');
+      css = sass
+        .renderSync({
+          outputStyle: mode === 'production' ? 'compressed' : undefined,
+          data: code,
+          includePaths,
+        })
+        .css.toString('utf8');
       break;
     }
     default: {
@@ -96,7 +107,7 @@ async function transformStyle(code: string, { type, filename, scopedClass }: { t
 }
 
 /** Style optimizer */
-export default function ({ filename, fileID }: { filename: string; fileID: string }): Optimizer {
+export default function optimizeStyles({ compileOptions, filename, fileID }: OptimizeOptions): Optimizer {
   const styleNodes: TemplateNode[] = []; // <style> tags to be updated
   const styleTransformPromises: Promise<StyleTransformResult>[] = []; // async style transform results to be finished in finalize();
   const scopedClass = `astro-${hashFromFilename(fileID)}`; // this *should* generate same hash from fileID every time
@@ -118,6 +129,7 @@ export default function ({ filename, fileID }: { filename: string; fileID: strin
                   type: (langAttr && langAttr.value[0] && langAttr.value[0].data) || undefined,
                   filename,
                   scopedClass,
+                  mode: compileOptions.mode,
                 })
               );
               return;
@@ -164,6 +176,7 @@ export default function ({ filename, fileID }: { filename: string; fileID: strin
                 type: (langAttr && langAttr.value[0] && langAttr.value[0].data) || undefined,
                 filename,
                 scopedClass,
+                mode: compileOptions.mode,
               })
             );
           },
diff --git a/src/dev.ts b/src/dev.ts
index bb12d2ca5b18..f2cd6a80d739 100644
--- a/src/dev.ts
+++ b/src/dev.ts
@@ -21,7 +21,7 @@ const logging: LogOptions = {
 export default async function (astroConfig: AstroConfig) {
   const { projectRoot } = astroConfig;
 
-  const runtime = await createRuntime(astroConfig, { logging });
+  const runtime = await createRuntime(astroConfig, { mode: 'development', logging });
 
   const server = http.createServer(async (req, res) => {
     const result = await runtime.load(req.url);
diff --git a/src/runtime.ts b/src/runtime.ts
index e0ac09de7b8d..0d8a34035447 100644
--- a/src/runtime.ts
+++ b/src/runtime.ts
@@ -1,5 +1,5 @@
 import type { SnowpackDevServer, ServerRuntime as SnowpackServerRuntime, SnowpackConfig } from 'snowpack';
-import type { AstroConfig } from './@types/astro';
+import type { AstroConfig, RuntimeMode } from './@types/astro';
 import type { LogOptions } from './logger';
 import type { CompileError } from './parser/utils/error.js';
 import { debug, info } from './logger.js';
@@ -10,6 +10,7 @@ import { loadConfiguration, logger as snowpackLogger, startServer as startSnowpa
 interface RuntimeConfig {
   astroConfig: AstroConfig;
   logging: LogOptions;
+  mode: RuntimeMode;
   backendSnowpack: SnowpackDevServer;
   backendSnowpackRuntime: SnowpackServerRuntime;
   backendSnowpackConfig: SnowpackConfig;
@@ -129,6 +130,7 @@ export interface AstroRuntime {
 }
 
 interface RuntimeOptions {
+  mode: RuntimeMode;
   logging: LogOptions;
 }
 
@@ -187,7 +189,7 @@ async function createSnowpack(astroConfig: AstroConfig, env: Record<string, any>
   return { snowpack, snowpackRuntime, snowpackConfig };
 }
 
-export async function createRuntime(astroConfig: AstroConfig, { logging }: RuntimeOptions): Promise<AstroRuntime> {
+export async function createRuntime(astroConfig: AstroConfig, { mode, logging }: RuntimeOptions): Promise<AstroRuntime> {
   const { snowpack: backendSnowpack, snowpackRuntime: backendSnowpackRuntime, snowpackConfig: backendSnowpackConfig } = await createSnowpack(astroConfig, {
     astro: true,
   });
@@ -199,6 +201,7 @@ export async function createRuntime(astroConfig: AstroConfig, { logging }: Runti
   const runtimeConfig: RuntimeConfig = {
     astroConfig,
     logging,
+    mode,
     backendSnowpack,
     backendSnowpackRuntime,
     backendSnowpackConfig,