diff --git a/apps/readest-app/src/app/reader/components/FoliateViewer.tsx b/apps/readest-app/src/app/reader/components/FoliateViewer.tsx
index 4a2da498..3cb2cfbd 100644
--- a/apps/readest-app/src/app/reader/components/FoliateViewer.tsx
+++ b/apps/readest-app/src/app/reader/components/FoliateViewer.tsx
@@ -9,7 +9,7 @@ import { useClickEvent, useTouchEvent } from '../hooks/useIframeEvents';
 import { useFoliateEvents } from '../hooks/useFoliateEvents';
 import { useProgressSync } from '../hooks/useProgressSync';
 import { useProgressAutoSave } from '../hooks/useProgressAutoSave';
-import { getStyles, mountAdditionalFonts } from '@/utils/style';
+import { getStyles, mountAdditionalFonts, transformStylesheet } from '@/utils/style';
 import { getBookDirFromLanguage, getBookDirFromWritingMode } from '@/utils/book';
 import { useUICSS } from '@/hooks/useUICSS';
 import {
@@ -23,6 +23,7 @@ import {
   handleTouchEnd,
 } from '../utils/iframeEventHandlers';
 import { getMaxInlineSize } from '@/utils/config';
+import { transformContent } from '@/services/transformService';
 
 const FoliateViewer: React.FC<{
   bookKey: string;
@@ -53,6 +54,28 @@ const FoliateViewer: React.FC<{
     setProgress(bookKey, detail.cfi, detail.tocItem, detail.section, detail.location, detail.range);
   };
 
+  const docTransformHandler = (event: Event) => {
+    const { detail } = event as CustomEvent;
+    detail.data = Promise.resolve(detail.data)
+      .then((data) => {
+        const viewSettings = getViewSettings(bookKey)!;
+        if (detail.type === 'text/css') return transformStylesheet(data);
+        if (detail.type === 'application/xhtml+xml') {
+          const ctx = {
+            bookKey,
+            viewSettings,
+            content: data,
+          };
+          return Promise.resolve(transformContent(ctx));
+        }
+        return data;
+      })
+      .catch((e) => {
+        console.error(new Error(`Failed to load ${detail.name}`, { cause: e }));
+        return '';
+      });
+  };
+
   const docLoadHandler = (event: Event) => {
     const detail = (event as CustomEvent).detail;
     console.log('doc loaded:', detail);
@@ -154,6 +177,9 @@ const FoliateViewer: React.FC<{
       viewRef.current = view;
       setFoliateView(bookKey, view);
 
+      const { book } = view;
+
+      book.transformTarget?.addEventListener('data', docTransformHandler);
       view.renderer.setStyles?.(getStyles(viewSettings));
 
       const isScrolled = viewSettings.scrolled!;
diff --git a/apps/readest-app/src/app/reader/components/settings/LayoutPanel.tsx b/apps/readest-app/src/app/reader/components/settings/LayoutPanel.tsx
index dae404ec..0aaddad2 100644
--- a/apps/readest-app/src/app/reader/components/settings/LayoutPanel.tsx
+++ b/apps/readest-app/src/app/reader/components/settings/LayoutPanel.tsx
@@ -122,7 +122,9 @@ const LayoutPanel: React.FC<{ bookKey: string }> = ({ bookKey }) => {
     if (writingMode === viewSettings.writingMode) return;
     // global settings are not supported for writing mode
     const prevWritingMode = viewSettings.writingMode;
-    if (!writingMode.includes('vertical')) {
+    if (writingMode.includes('vertical')) {
+      viewSettings.vertical = true;
+    } else {
       viewSettings.vertical = false;
     }
     saveViewSettings(envConfig, bookKey, 'writingMode', writingMode, true);
diff --git a/apps/readest-app/src/libs/document.ts b/apps/readest-app/src/libs/document.ts
index a456d7e0..b4ec878f 100644
--- a/apps/readest-app/src/libs/document.ts
+++ b/apps/readest-app/src/libs/document.ts
@@ -66,6 +66,7 @@ export interface BookDoc {
   dir: string;
   toc?: Array<TOCItem>;
   sections?: Array<SectionItem>;
+  transformTarget?: EventTarget;
   splitTOCHref(href: string): Array<string | number>;
   getCover(): Promise<Blob | null>;
 }
diff --git a/apps/readest-app/src/services/transformService.ts b/apps/readest-app/src/services/transformService.ts
new file mode 100644
index 00000000..0db64743
--- /dev/null
+++ b/apps/readest-app/src/services/transformService.ts
@@ -0,0 +1,16 @@
+import { activeTransformers } from './transformers';
+import { TransformContext } from './transformers/types';
+
+export const transformContent = async (ctx: TransformContext): Promise<string> => {
+  let transformed = ctx.content;
+
+  for (const transformer of activeTransformers) {
+    try {
+      transformed = await transformer.transform({ ...ctx, content: transformed });
+    } catch (error) {
+      console.warn(`Error in transformer ${transformer.name}:`, error);
+    }
+  }
+
+  return transformed;
+};
diff --git a/apps/readest-app/src/services/transformers/index.ts b/apps/readest-app/src/services/transformers/index.ts
new file mode 100644
index 00000000..c7da70c2
--- /dev/null
+++ b/apps/readest-app/src/services/transformers/index.ts
@@ -0,0 +1,9 @@
+import type { Transformer } from './types';
+import { translateTransformer } from './translate';
+import { punctuationTransformer } from './punctuation';
+
+export const activeTransformers: Transformer[] = [
+  punctuationTransformer,
+  translateTransformer,
+  // Add more transformers here
+];
diff --git a/apps/readest-app/src/services/transformers/punctuation.ts b/apps/readest-app/src/services/transformers/punctuation.ts
new file mode 100644
index 00000000..ea07aa2d
--- /dev/null
+++ b/apps/readest-app/src/services/transformers/punctuation.ts
@@ -0,0 +1,41 @@
+import type { Transformer } from './types';
+
+const punctuationMap: Record<string, string> = {
+  '，': '︐', // full-width comma
+  '。': '︒', // full stop
+  '、': '︑', // enumeration comma
+  '：': '︓', // colon
+  '；': '︔', // semicolon
+  '！': '︕', // exclamation
+  '？': '︖', // question
+  '（': '︵',
+  '）': '︶',
+  '《': '︽',
+  '》': '︾',
+  '「': '﹁',
+  '」': '﹂',
+  '『': '﹃',
+  '』': '﹄',
+  '“': '﹁',
+  '”': '﹂',
+  '‘': '﹃',
+  '’': '﹄',
+};
+
+export const punctuationTransformer: Transformer = {
+  name: 'punctuation',
+
+  transform: async (ctx) => {
+    if (!ctx.content.includes('<html')) return ctx.content;
+
+    const shouldTransform = ctx.viewSettings.vertical === true;
+    if (!shouldTransform) return ctx.content;
+
+    let result = ctx.content;
+    for (const [original, vertical] of Object.entries(punctuationMap)) {
+      result = result.replace(new RegExp(original, 'g'), vertical);
+    }
+
+    return result;
+  },
+};
diff --git a/apps/readest-app/src/services/transformers/translate.ts b/apps/readest-app/src/services/transformers/translate.ts
new file mode 100644
index 00000000..abb2d9ad
--- /dev/null
+++ b/apps/readest-app/src/services/transformers/translate.ts
@@ -0,0 +1,9 @@
+import type { Transformer } from './types';
+
+export const translateTransformer: Transformer = {
+  name: 'translate',
+
+  transform: async (ctx) => {
+    return ctx.content;
+  },
+};
diff --git a/apps/readest-app/src/services/transformers/types.ts b/apps/readest-app/src/services/transformers/types.ts
new file mode 100644
index 00000000..5cc1cbda
--- /dev/null
+++ b/apps/readest-app/src/services/transformers/types.ts
@@ -0,0 +1,12 @@
+import { ViewSettings } from '@/types/book';
+
+export type TransformContext = {
+  bookKey: string;
+  viewSettings: ViewSettings;
+  content: string;
+};
+
+export type Transformer = {
+  name: string;
+  transform: (ctx: TransformContext) => Promise<string>;
+};
diff --git a/apps/readest-app/src/utils/style.ts b/apps/readest-app/src/utils/style.ts
index 41ab62a8..af17cbc3 100644
--- a/apps/readest-app/src/utils/style.ts
+++ b/apps/readest-app/src/utils/style.ts
@@ -207,12 +207,11 @@ const getLayoutStyles = (
     background-color: transparent !important;
   }
   p, li, blockquote, dd {
-    margin: ${vertical ? `0 ${paragraphMargin}em` : `${paragraphMargin}em 0`} ${overrideLayout ? '!important' : ''};
     line-height: ${lineSpacing} ${overrideLayout ? '!important' : ''};
     word-spacing: ${wordSpacing}px ${overrideLayout ? '!important' : ''};
     letter-spacing: ${letterSpacing}px ${overrideLayout ? '!important' : ''};
-    text-indent: ${textIndent}em ${overrideLayout ? '!important' : ''};
-    text-align: ${overrideLayout ? 'var(--default-text-align) !important' : 'inherit'};
+    text-indent: ${vertical ? textIndent * 1.2 : textIndent}em;
+    text-align: ${overrideLayout ? 'var(--default-text-align)' : 'inherit'};
     -webkit-hyphens: ${hyphenate ? 'auto' : 'manual'};
     hyphens: ${hyphenate ? 'auto' : 'manual'};
     -webkit-hyphenate-limit-before: 3;
@@ -221,6 +220,12 @@ const getLayoutStyles = (
     hanging-punctuation: allow-end last;
     widows: 2;
   }
+  p {
+    ${vertical ? `margin-left: ${paragraphMargin}em ${overrideLayout ? '!important' : ''};` : ''}
+    ${vertical ? `margin-right: ${paragraphMargin}em ${overrideLayout ? '!important' : ''};` : ''}
+    ${!vertical ? `margin-top: ${paragraphMargin}em ${overrideLayout ? '!important' : ''};` : ''}
+    ${!vertical ? `margin-bottom: ${paragraphMargin}em ${overrideLayout ? '!important' : ''};` : ''}
+  }
   li, p:has(> :is(img, video, font, h1, h2, h3, h4, h5, table)) {
     text-indent: 0 !important;
   }
@@ -240,6 +245,14 @@ const getLayoutStyles = (
     display: none;
   }
 
+  img.pi {
+    ${vertical ? 'transform: rotate(90deg);' : ''}
+    ${vertical ? 'transform-origin: center;' : ''}
+    ${vertical ? 'height: 2em;' : ''}
+    ${vertical ? `width: ${lineSpacing}em;` : ''}
+    ${vertical ? `vertical-align: unset;` : ''}
+  }
+
   .duokan-footnote-content,
   .duokan-footnote-item {
     display: none;
@@ -384,3 +397,20 @@ export const mountAdditionalFonts = (document: Document) => {
   style.textContent = getAdditionalFontFaces();
   document.head.appendChild(style);
 };
+
+export const transformStylesheet = (css: string) => {
+  // replace absolute font sizes with rem units
+  // replace hardcoded colors
+  return css
+    .replace(/font-size\s*:\s*xx-small/gi, 'font-size: 0.6rem')
+    .replace(/font-size\s*:\s*x-small/gi, 'font-size: 0.75rem')
+    .replace(/font-size\s*:\s*small/gi, 'font-size: 0.875rem')
+    .replace(/font-size\s*:\s*medium/gi, 'font-size: 1rem')
+    .replace(/font-size\s*:\s*large/gi, 'font-size: 1.2rem')
+    .replace(/font-size\s*:\s*x-large/gi, 'font-size: 1.5rem')
+    .replace(/font-size\s*:\s*xx-large/gi, 'font-size: 2rem')
+    .replace(/font-size\s*:\s*xxx-large/gi, 'font-size: 3rem')
+    .replace(/\scolor\s*:\s*#000000/gi, 'color: var(--theme-fg-color)')
+    .replace(/\scolor\s*:\s*#000/gi, 'color: var(--theme-fg-color)')
+    .replace(/\scolor\s*:\s*rgb\(0,\s*0,\s*0\)/gi, 'color: var(--theme-fg-color)');
+};
diff --git a/packages/foliate-js b/packages/foliate-js
index 605246a3..be37c6c0 160000
--- a/packages/foliate-js
+++ b/packages/foliate-js
@@ -1 +1 @@
-Subproject commit 605246a3753e2677de3a4104f6cc8e8edff5c19a
+Subproject commit be37c6c03b286630e50b86e4e158b00bb388a9cf