diff --git a/packages/ui/src/components/file-ssr.tsx b/packages/ui/src/components/file-ssr.tsx
index 9526907831..118d9c4fde 100644
--- a/packages/ui/src/components/file-ssr.tsx
+++ b/packages/ui/src/components/file-ssr.tsx
@@ -6,13 +6,7 @@ import { useWorkerPool } from "../context/worker-pool"
 import { createDefaultOptions, styleVariables } from "../pierre"
 import { markCommentedDiffLines } from "../pierre/commented-lines"
 import { fixDiffSelection } from "../pierre/diff-selection"
-import {
-  applyViewerScheme,
-  clearReadyWatcher,
-  createReadyWatcher,
-  notifyShadowReady,
-  observeViewerScheme,
-} from "../pierre/file-runtime"
+import { clearReadyWatcher, createReadyWatcher, notifyShadowReady } from "../pierre/file-runtime"
 import { acquireVirtualizer, virtualMetrics } from "../pierre/virtualizer"
 import { File, type DiffFileProps, type FileProps } from "./file"
 
@@ -87,8 +81,6 @@ function DiffSSRViewer<T>(props: SSRDiffFileProps<T>) {
   onMount(() => {
     if (isServer) return
 
-    onCleanup(observeViewerScheme(() => fileDiffRef))
-
     const virtualizer = getVirtualizer()
     fileDiffInstance = virtualizer
       ? new VirtualizedFileDiff<T>(
@@ -110,8 +102,6 @@ function DiffSSRViewer<T>(props: SSRDiffFileProps<T>) {
           workerPool,
         )
 
-    applyViewerScheme(fileDiffRef)
-
     // @ts-expect-error private field required for hydration
     fileDiffInstance.fileContainer = fileDiffRef
     fileDiffInstance.hydrate({
diff --git a/packages/ui/src/components/file.tsx b/packages/ui/src/components/file.tsx
index 15915dd52d..81e4bbda97 100644
--- a/packages/ui/src/components/file.tsx
+++ b/packages/ui/src/components/file.tsx
@@ -16,20 +16,12 @@ import {
 } from "@pierre/diffs"
 import { type PreloadMultiFileDiffResult } from "@pierre/diffs/ssr"
 import { createMediaQuery } from "@solid-primitives/media"
-import { ComponentProps, createEffect, createMemo, createSignal, onCleanup, onMount, Show, splitProps } from "solid-js"
+import { ComponentProps, createEffect, createMemo, createSignal, onCleanup, Show, splitProps } from "solid-js"
 import { createDefaultOptions, styleVariables } from "../pierre"
 import { markCommentedDiffLines, markCommentedFileLines } from "../pierre/commented-lines"
 import { fixDiffSelection, findDiffSide, type DiffSelectionSide } from "../pierre/diff-selection"
 import { createFileFind } from "../pierre/file-find"
-import {
-  applyViewerScheme,
-  clearReadyWatcher,
-  createReadyWatcher,
-  getViewerHost,
-  getViewerRoot,
-  notifyShadowReady,
-  observeViewerScheme,
-} from "../pierre/file-runtime"
+import { clearReadyWatcher, createReadyWatcher, getViewerRoot, notifyShadowReady } from "../pierre/file-runtime"
 import {
   findCodeSelectionSide,
   findDiffLineNumber,
@@ -154,7 +146,6 @@ function useFileViewer(config: ViewerConfig) {
   const [rendered, setRendered] = createSignal(0)
 
   const getRoot = () => getViewerRoot(container)
-  const getHost = () => getViewerHost(container)
 
   const find = createFileFind({
     wrapper: () => wrapper,
@@ -265,10 +256,6 @@ function useFileViewer(config: ViewerConfig) {
 
   // -- shared effects --
 
-  onMount(() => {
-    onCleanup(observeViewerScheme(getHost))
-  })
-
   createEffect(() => {
     rendered()
     const ranges = config.commentedLines()
@@ -351,7 +338,6 @@ function useFileViewer(config: ViewerConfig) {
     rendered,
     setRendered,
     getRoot,
-    getHost,
     find,
     scheduleSelectionUpdate,
   }
@@ -486,7 +472,6 @@ function renderViewer<I extends RenderTarget>(opts: {
   opts.viewer.container.innerHTML = ""
   opts.draw(next)
 
-  applyViewerScheme(opts.viewer.getHost())
   opts.viewer.setRendered((value) => value + 1)
   opts.onReady()
 }
diff --git a/packages/ui/src/pierre/file-runtime.ts b/packages/ui/src/pierre/file-runtime.ts
index a207210035..c2c4229133 100644
--- a/packages/ui/src/pierre/file-runtime.ts
+++ b/packages/ui/src/pierre/file-runtime.ts
@@ -23,31 +23,6 @@ export function getViewerRoot(container: HTMLElement | undefined) {
   return getViewerHost(container)?.shadowRoot ?? undefined
 }
 
-export function applyViewerScheme(host: HTMLElement | undefined) {
-  if (!host) return
-  if (typeof document === "undefined") return
-
-  const scheme = document.documentElement.dataset.colorScheme
-  if (scheme === "dark" || scheme === "light") {
-    host.dataset.colorScheme = scheme
-    return
-  }
-
-  host.removeAttribute("data-color-scheme")
-}
-
-export function observeViewerScheme(getHost: () => HTMLElement | undefined) {
-  if (typeof document === "undefined") return () => {}
-
-  applyViewerScheme(getHost())
-  if (typeof MutationObserver === "undefined") return () => {}
-
-  const root = document.documentElement
-  const monitor = new MutationObserver(() => applyViewerScheme(getHost()))
-  monitor.observe(root, { attributes: true, attributeFilter: ["data-color-scheme"] })
-  return () => monitor.disconnect()
-}
-
 export function notifyShadowReady(opts: {
   state: ReadyWatcher
   container: HTMLElement
diff --git a/packages/ui/src/pierre/index.ts b/packages/ui/src/pierre/index.ts
index 22586f0f58..6bf59d89c7 100644
--- a/packages/ui/src/pierre/index.ts
+++ b/packages/ui/src/pierre/index.ts
@@ -37,26 +37,19 @@ const unsafeCSS = `
   --diffs-bg-addition-emphasis: var(--diffs-bg-addition-emphasis-override, light-dark(rgb(from var(--diffs-addition-base) r g b / 0.07), rgb(from var(--diffs-addition-base) r g b / 0.1)));
   --diffs-selection-base: var(--surface-warning-strong);
   --diffs-selection-border: var(--border-warning-base);
-  --diffs-selection-number-fg: #1c1917;
+  --diffs-selection-number-fg: light-dark(#1c1917, #fdfbfb);
   /* Use explicit alpha instead of color-mix(..., transparent) to avoid Safari's non-premultiplied interpolation bugs. */
-  --diffs-bg-selection: var(--diffs-bg-selection-override, rgb(from var(--surface-warning-base) r g b / 0.65));
+  --diffs-bg-selection: var(
+    --diffs-bg-selection-override,
+    light-dark(rgb(from var(--surface-warning-base) r g b / 0.65), rgb(from var(--solaris-dark-6) r g b / 0.65))
+  );
   --diffs-bg-selection-number: var(
     --diffs-bg-selection-number-override,
-    rgb(from var(--surface-warning-base) r g b / 0.85)
+    light-dark(rgb(from var(--surface-warning-base) r g b / 0.85), rgb(from var(--solaris-dark-6) r g b / 0.85))
   );
   --diffs-bg-selection-text: rgb(from var(--surface-warning-strong) r g b / 0.2);
 }
 
-:host([data-color-scheme='dark']) [data-diff],
-:host([data-color-scheme='dark']) [data-file] {
-  --diffs-selection-number-fg: #fdfbfb;
-  --diffs-bg-selection: var(--diffs-bg-selection-override, rgb(from var(--solaris-dark-6) r g b / 0.65));
-  --diffs-bg-selection-number: var(
-    --diffs-bg-selection-number-override,
-    rgb(from var(--solaris-dark-6) r g b / 0.85)
-  );
-}
-
 [data-diff] ::selection,
 [data-file] ::selection {
   background-color: var(--diffs-bg-selection-text);