diff --git a/src/config/theme.ts b/src/config/theme.ts
index 4fb0cec..0c06a51 100644
--- a/src/config/theme.ts
+++ b/src/config/theme.ts
@@ -1,37 +1,29 @@
 interface Theme {
-  BASE: Record<string, string | number>
+  base: Record<string, string | number>
   block: Record<string, Record<string, string | number>>
   inline: Record<string, Record<string, string | number>>
 }
 
 const baseColor = `#3f3f3f`
 
-function mergeTheme(defaultTheme: Theme, newTheme: Theme) {
-  const res: Theme = {
-    BASE: {
-      ...defaultTheme.BASE,
-      ...newTheme.BASE,
-    },
-    block: {},
-    inline: {},
-  }
-  for (const el in defaultTheme.block) {
-    res.block[el] = {
-      ...defaultTheme.block[el],
-      ...newTheme.block[el],
+function mergeTheme(defaultTheme: Theme, newTheme: Theme): Theme {
+  const merge = (defaultObj: Record<string, any>, newObj: Record<string, any>) => {
+    const result: Record<string, any> = {}
+    for (const key in defaultObj) {
+      result[key] = { ...defaultObj[key], ...newObj?.[key] }
     }
+    return result
   }
-  for (const el in defaultTheme.inline) {
-    res.inline[el] = {
-      ...defaultTheme.inline[el],
-      ...newTheme.inline[el],
-    }
+
+  return {
+    base: { ...defaultTheme.base, ...newTheme.base },
+    block: merge(defaultTheme.block, newTheme.block),
+    inline: merge(defaultTheme.inline, newTheme.inline),
   }
-  return res
 }
 
 const defaultTheme = {
-  BASE: {
+  base: {
     '--md-primary-color': `#000000`,
     'text-align': `left`,
     'line-height': `1.75`,
@@ -225,7 +217,7 @@ const defaultTheme = {
 }
 
 const graceTheme = mergeTheme(defaultTheme, {
-  BASE: {
+  base: {
   },
   block: {
     h1: {
diff --git a/src/stores/index.js b/src/stores/index.js
index 2646160..a24bff8 100644
--- a/src/stores/index.js
+++ b/src/stores/index.js
@@ -6,10 +6,10 @@ import { useDark, useStorage, useToggle } from '@vueuse/core'
 import { ElMessage, ElMessageBox } from 'element-plus'
 
 import { altKey, codeBlockThemeOptions, colorOptions, fontFamilyOptions, fontSizeOptions, legendOptions, shiftKey, themeMap, themeOptions } from '@/config'
-import WxRenderer from '@/utils/wx-renderer'
+import WxRenderer from '@/utils/renderer'
 import DEFAULT_CONTENT from '@/assets/example/markdown.md?raw'
 import DEFAULT_CSS_CONTENT from '@/assets/example/theme-css.txt?raw'
-import { addPrefix, css2json, customCssWithTemplate, downloadMD, exportHTML, formatCss, formatDoc, setColorWithCustomTemplate, setFontSizeWithTemplate, setTheme } from '@/utils'
+import { addPrefix, css2json, customCssWithTemplate, customizeTheme, downloadMD, exportHTML, formatCss, formatDoc } from '@/utils'
 
 export const useStore = defineStore(`store`, () => {
   // 是否开启深色模式
@@ -46,7 +46,7 @@ export const useStore = defineStore(`store`, () => {
   const fontSizeNumber = fontSize.value.replace(`px`, ``)
 
   const wxRenderer = new WxRenderer({
-    theme: setTheme(themeMap[theme.value], fontSizeNumber, fontColor.value, theme.value === `default`),
+    theme: customizeTheme(themeMap[theme.value], { fontSize: fontSizeNumber, color: fontColor.value }),
     fonts: fontFamily.value,
     size: fontSize.value,
   })
@@ -187,11 +187,9 @@ export const useStore = defineStore(`store`, () => {
   // 更新 CSS
   const updateCss = () => {
     const json = css2json(cssEditor.value.getValue())
-    let t = setTheme(themeMap[theme.value], fontSizeNumber, fontColor.value, theme.value === `default`)
-
-    t = customCssWithTemplate(json, fontColor.value, t)
+    const newTheme = customCssWithTemplate(json, fontColor.value, customizeTheme(themeMap[theme.value], { fontSize: fontSizeNumber, color: fontColor.value }))
     wxRenderer.setOptions({
-      theme: t,
+      theme: newTheme,
     })
     editorRefresh()
   }
@@ -270,15 +268,15 @@ export const useStore = defineStore(`store`, () => {
   }
 
   const getTheme = (size, color) => {
-    const t = setFontSizeWithTemplate(themeMap[theme.value])(size.replace(`px`, ``), theme.value === `default`)
-    return setColorWithCustomTemplate(t, color, theme.value === `default`)
+    const newTheme = themeMap[theme.value]
+    const fontSize = size.replace(`px`, ``)
+    return customizeTheme(newTheme, { fontSize, color })
   }
 
   const themeChanged = withAfterRefresh((newTheme) => {
     wxRenderer.setOptions({
-      theme: setTheme(themeMap[newTheme], fontSizeNumber, fontColor.value, newTheme === `default`),
+      theme: customizeTheme(themeMap[newTheme], { fontSize: fontSizeNumber, color: fontColor.value }),
     })
-
     theme.value = newTheme
   })
 
diff --git a/src/utils/index.js b/src/utils/index.js
index 664ffd1..2165d79 100644
--- a/src/utils/index.js
+++ b/src/utils/index.js
@@ -9,86 +9,44 @@ export function addPrefix(str) {
   return `${prefix}__${str}`
 }
 
-// 设置自定义颜色
-function createCustomTheme(theme, color) {
-  const customTheme = JSON.parse(JSON.stringify(theme))
-  customTheme.BASE[`--md-primary-color`] = color
-  return customTheme
-}
-
-export function setColorWithCustomTemplate(theme, color, isDefault = true) {
-  return createCustomTheme(theme, color, isDefault)
-}
-
-// 设置自定义字体大小
-export function setFontSizeWithTemplate(template) {
-  return function (fontSize) {
-    const customTheme = JSON.parse(JSON.stringify(template))
+export function customizeTheme(theme, options) {
+  const newTheme = JSON.parse(JSON.stringify(theme))
+  const { fontSize, color } = options
+  if (fontSize) {
     for (let i = 1; i <= 4; i++) {
-      const v = customTheme.block[`h${i}`][`font-size`]
-      customTheme.block[`h${i}`][`font-size`] = `${fontSize * Number.parseFloat(v)}px`
+      const v = newTheme.block[`h${i}`][`font-size`]
+      newTheme.block[`h${i}`][`font-size`] = `${fontSize * Number.parseFloat(v)}px`
     }
-    return customTheme
   }
-}
-
-export function setTheme(theme, fontSize, color, isDefault) {
-  return setColorWithCustomTemplate(setFontSizeWithTemplate(theme)(fontSize, isDefault), color, isDefault)
+  if (color) {
+    newTheme.base[`--md-primary-color`] = color
+  }
+  return newTheme
 }
 
 export function customCssWithTemplate(jsonString, color, theme) {
-  // block
-  const customTheme = createCustomTheme(theme, color)
+  const newTheme = customizeTheme(theme, { color });
 
-  customTheme.block.h1 = Object.assign(customTheme.block.h1, jsonString.h1)
-  customTheme.block.h2 = Object.assign(customTheme.block.h2, jsonString.h2)
-  customTheme.block.h3 = Object.assign(customTheme.block.h3, jsonString.h3)
-  customTheme.block.h4 = Object.assign(customTheme.block.h4, jsonString.h4)
-  customTheme.block.code = Object.assign(
-    customTheme.block.code,
-    jsonString.code,
-  )
-  customTheme.block.p = Object.assign(customTheme.block.p, jsonString.p)
-  customTheme.block.hr = Object.assign(customTheme.block.hr, jsonString.hr)
-  customTheme.block.blockquote = Object.assign(
-    customTheme.block.blockquote,
-    jsonString.blockquote,
-  )
-  customTheme.block.blockquote_p = Object.assign(
-    customTheme.block.blockquote_p,
-    jsonString.blockquote_p,
-  )
-  customTheme.block.image = Object.assign(
-    customTheme.block.image,
-    jsonString.image,
-  )
+  const mergeProperties = (target, source, keys) => {
+    keys.forEach(key => {
+      if (source[key]) {
+        target[key] = Object.assign(target[key] || {}, source[key]);
+      }
+    });
+  };
 
-  // inline
-  customTheme.inline.strong = Object.assign(
-    customTheme.inline.strong,
-    jsonString.strong,
-  )
-  customTheme.inline.codespan = Object.assign(
-    customTheme.inline.codespan,
-    jsonString.codespan,
-  )
-  customTheme.inline.link = Object.assign(
-    customTheme.inline.link,
-    jsonString.link,
-  )
-  customTheme.inline.wx_link = Object.assign(
-    customTheme.inline.wx_link,
-    jsonString.wx_link,
-  )
-  customTheme.block.ul = Object.assign(customTheme.block.ul, jsonString.ul)
-  customTheme.block.ol = Object.assign(customTheme.block.ol, jsonString.ol)
-  customTheme.inline.listitem = Object.assign(
-    customTheme.inline.listitem,
-    jsonString.li,
-  )
-  return customTheme
+  const blockKeys = [
+    'h1', 'h2', 'h3', 'h4', 'code', 'p', 'hr', 'blockquote',
+    'blockquote_p', 'image', 'ul', 'ol'
+  ];
+  const inlineKeys = ['strong', 'codespan', 'link', 'wx_link', 'listitem'];
+
+  mergeProperties(newTheme.block, jsonString, blockKeys);
+  mergeProperties(newTheme.inline, jsonString, inlineKeys);
+  return newTheme;
 }
 
+
 /**
  * 将 CSS 字符串转换为 JSON 对象
  *
diff --git a/src/utils/wx-renderer.js b/src/utils/renderer.js
similarity index 99%
rename from src/utils/wx-renderer.js
rename to src/utils/renderer.js
index fdad49f..1a03260 100644
--- a/src/utils/wx-renderer.js
+++ b/src/utils/renderer.js
@@ -28,7 +28,7 @@ class WxRenderer extends Renderer {
   merge = (base, extend) => ({ ...base, ...extend })
 
   buildTheme = (themeTpl) => {
-    const base = this.merge(themeTpl.BASE, {
+    const base = this.merge(themeTpl.base, {
       'font-family': this.opts.fonts,
       'font-size': this.opts.size,
     })