diff --git a/1000-hours/.vitepress/theme/components/ThemedImageSwitch.vue b/1000-hours/.vitepress/theme/components/ThemedImageSwitch.vue
new file mode 100644
index 00000000..1e8e9284
--- /dev/null
+++ b/1000-hours/.vitepress/theme/components/ThemedImageSwitch.vue
@@ -0,0 +1,91 @@
+<template>
+</template>
+
+<script setup lang="ts">
+import { computed, onMounted, ref } from "vue";
+
+const currentTheme = ref('light');
+
+const props = defineProps({
+  base: {
+    type: String,
+    required: true,
+  },
+  res: {
+    type: String,
+    required: true,
+  },
+  alt: {
+    type: String,
+    default: "",
+  },
+});
+
+const imgUrl = computed(() => {
+  if (isDarkTheme()) {
+    return `${props.base}/${props.res}.dark.svg`;
+  }
+  return `${props.base}/${props.res}.light.svg`;
+});
+
+function isDarkTheme() {
+  // check html element class, if it is dark, return true
+  let ret = document.documentElement.classList.contains('dark');
+  if (currentTheme.value === 'dark') {
+    ret = true
+  }
+  return ret;
+}
+
+function switchImagesTheme(isDark:boolean) {
+  const themedImages = document.querySelectorAll('img.themed');
+  for (let i = 0; i < themedImages.length; i ++) {
+    const img:any = themedImages[i];
+    const originalSrc:any = img.getAttribute('src')
+    const parts = originalSrc.split('.');
+    const prefix = parts.shift();
+    const ext = parts.pop();
+    const mid = isDark ? 'dark' : 'light';
+    if (prefix && ext && (prefix !== ext)) {
+      const newSrc = `${prefix}.${mid}.${ext}`
+      img.onerror = () => {
+        img.setAttribute('src', originalSrc);
+      }
+      img.setAttribute('src', newSrc);
+    }
+  }
+}
+
+onMounted(() => {
+  const htmlEle:any = document.querySelector('html');
+  const observer = new MutationObserver((mutationsList, observer) => {
+    for(const mutation of mutationsList) {
+      if (mutation.type === 'attributes' && mutation.attributeName === 'class') {
+        switchImagesTheme(htmlEle.classList.contains('dark'))
+      }
+    }
+  });
+
+  const config = {
+    attributes: true,
+    attributeFilter: ['class']
+  };
+  observer.observe(htmlEle, config);
+
+  // apply html
+  switchImagesTheme(htmlEle.classList.contains('dark'))
+});
+</script>
+
+
+<style lang="scss" scoped>
+.image-wrapper {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  img {
+    width: 100%;
+    height: auto;
+  }
+}
+</style>
diff --git a/1000-hours/.vitepress/theme/index.ts b/1000-hours/.vitepress/theme/index.ts
index 7e61e7d3..61a71b0b 100644
--- a/1000-hours/.vitepress/theme/index.ts
+++ b/1000-hours/.vitepress/theme/index.ts
@@ -16,6 +16,7 @@ export default {
   // },
   enhanceApp({ app, router, siteData }) {
     // ...
+    app.component('Image', Image)
     app.component('SpeakWord', SpeakWord)
   }
 } satisfies Theme
diff --git a/1000-hours/.vitepress/theme/layouts/index.vue b/1000-hours/.vitepress/theme/layouts/index.vue
index e4580981..cee94a85 100644
--- a/1000-hours/.vitepress/theme/layouts/index.vue
+++ b/1000-hours/.vitepress/theme/layouts/index.vue
@@ -1,6 +1,7 @@
 <script setup>
 import DefaultTheme from 'vitepress/theme'
 import SpeakWordInlineConverter from '../components/SpeakWordInlineConverter.vue'
+import ThemedImageSwitch from '../components/ThemedImageSwitch.vue'
 
 const { Layout } = DefaultTheme
 
@@ -11,6 +12,7 @@ const { Layout } = DefaultTheme
     <template #doc-after>
       <ClientOnly>
         <SpeakWordInlineConverter />
+        <ThemedImageSwitch />
       </ClientOnly>
     </template>
   </Layout>
diff --git a/1000-hours/public/images/speech-tract-l.dark.svg b/1000-hours/public/images/speech-tract-l.dark.svg
new file mode 100644
index 00000000..ee32f67f
--- /dev/null
+++ b/1000-hours/public/images/speech-tract-l.dark.svg
@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="1280px" height="800px" viewBox="0 0 1280 800" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <title>speech-tract-l</title>
+    <g id="Page-1" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
+        <g id="speech-tract-l">
+            <rect id="Rectangle" x="0" y="0" width="1280" height="800"></rect>
+            <g id="speech-tract-copy-2" transform="translate(353, 30)">
+                <path d="M41.0086634,364.016671 C34.1286634,365.166671 31.0086634,378.016671 31.0086634,378.016671 C31.0086634,378.016671 28.4686634,386.406671 31.0086634,394.016671 C33.4686634,401.406671 37.8486634,405.566671 40.0086634,408.016671 C42.1686634,410.466671 44.6986634,414.656671 51.0086634,423.016671 C55.7886634,429.346671 62.7086634,435.526671 67.0086634,447.016671 C73.3986634,464.096671 75.2286634,485.166671 78.0086634,501.016671 C80.1986634,513.516671 83.4386634,522.786671 85.0086634,525.016671 C86.5786634,527.246671 86.6986634,530.286671 104.008663,534.016671 C118.738663,537.186671 146.268663,536.896671 168.008663,537.016671 C188.348663,537.126671 215.518663,535.016671 234.008663,532.016671 C255.598663,528.506671 260.918663,524.866671 267.008663,524.016671 C273.098663,523.166671 288.588663,518.226671 307.008663,533.016671 C324.028663,546.686671 327.008663,552.016671 327.008663,552.016671 C327.008663,552.016671 330.208663,557.676671 334.008663,568.016671 C341.168663,587.596671 332.248663,592.876671 337.008663,606.016671 C341.678663,618.896671 349.858663,611.696671 361.158663,642.916671 C376.358663,685.126671 391.008663,726.016671 391.008663,726.016671 C391.008663,726.016671 394.068663,737.266671 403.008663,740.016671 C406.358663,741.046671 409.148663,739.266671 413.008663,739.016671 C421.188663,738.486671 430.008663,738.016671 430.008663,738.016671 L467.008663,736.016671 L433.008663,702.016671 L393.008663,613.016671 L373.008663,526.016671 L419.008663,462.016671 L440.008663,430.016671 C440.008663,430.016671 461.778663,402.416671 426.008663,374.016671 C408.128663,360.686671 403.508663,354.936671 386.008663,350.016671 C302.378663,326.506671 256.308663,351.196671 242.008663,353.016671 C213.688663,356.616671 178.008663,356.016671 178.008663,356.016671 C178.008663,356.016671 165.638663,357.676671 164.008663,372.016671 C162.378663,386.356671 169.558663,389.916671 172.008663,392.016671 C174.458663,394.116671 176.268663,396.046671 181.008663,401.016671 C186.118663,406.376671 192.848663,412.946671 196.008663,420.016671 C199.918663,428.756671 195.808663,437.336671 194.008663,439.016671 C189.278663,443.426671 176.068663,432.266671 174.008663,430.016671 C166.548663,421.856671 160.248663,411.046671 155.008663,405.016671 C151.728663,401.236671 149.008663,401.016671 149.008663,401.016671 L129.008663,415.016671 L129.008663,449.016671 L116.008663,452.016671 L106.008663,447.016671 C106.008663,447.016671 103.348663,433.536671 99.0086634,419.016671 C93.4886634,400.526671 88.9786634,384.166671 86.0086634,380.016671 C83.0386634,375.866671 70.9786634,361.686671 41.0086634,364.016671 Z" id="Path" stroke="#FFFFFF" stroke-width="2" fill="#8A8A89"></path>
+                <path d="M478.008663,738.016671 C477.578663,738.406671 462.198663,736.246671 446.008663,731.016671 C434.768663,727.386671 423.298663,720.946671 417.008663,717.016671 C401.648663,707.416671 389.008663,663.016671 389.008663,663.016671 C389.008663,663.016671 373.608663,623.786671 362.008663,591.016671 C354.558663,569.956671 349.008663,550.016671 349.008663,550.016671 C349.008663,550.016671 346.308663,537.876671 335.008663,528.016671 C322.848663,517.406671 309.488663,513.476671 306.008663,512.016671 C302.528663,510.556671 297.718663,507.606671 299.008663,505.016671 C300.208663,502.616671 310.008663,503.016671 310.008663,503.016671 C310.008663,503.016671 318.488663,503.706671 328.008663,499.016671 C333.358663,496.376671 339.048663,489.466671 345.008663,486.016671 C361.118663,476.676671 377.008663,470.016671 377.008663,470.016671 L436.008663,447.016671 C436.008663,447.016671 451.908663,441.286671 464.008663,432.016671 C475.378663,423.306671 481.628663,410.976671 483.008663,411.016574 C484.388663,411.056671 486.818663,414.386671 486.750143,418.136671 C486.658663,423.466671 485.008663,430.016671 485.008663,430.016671 C485.008663,430.016671 481.348663,443.426671 478.008663,449.016671 C469.208663,463.766671 457.008663,475.016671 457.008663,475.016671 C457.008663,475.016671 442.268663,494.396671 428.008663,516.016671 C411.448663,541.126671 396.818663,564.756671 396.008663,566.016671 C395.198663,567.276671 390.938663,574.986671 394.008663,583.016671 C399.298663,596.836671 409.788663,609.036671 413.008663,616.016671 C416.228663,622.996671 416.408663,623.446671 421.298663,634.136671 C427.298663,647.246671 434.068663,665.836671 441.008663,681.016671 C448.538663,697.466671 453.998663,706.926671 456.008663,710.016671 C456.798663,711.226671 460.368663,715.816671 464.408663,720.936671 C467.568663,724.946671 471.368663,727.716671 474.008663,731.016671 C476.568663,734.216671 478.438663,737.626671 478.008663,738.016671 Z" id="Path" stroke="#FFFFFF" stroke-width="2" fill="#BFC0BF"></path>
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+                <text id="l" font-family="CourierNewPSMT, Courier New" font-size="36" font-weight="normal" fill="#000000">
+                    <tspan x="261" y="304">l</tspan>
+                </text>
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diff --git a/1000-hours/sounds-of-english/23-l.md b/1000-hours/sounds-of-english/23-l.md
index 9bc2f957..6c4a909c 100644
--- a/1000-hours/sounds-of-english/23-l.md
+++ b/1000-hours/sounds-of-english/23-l.md
@@ -11,3 +11,5 @@
 所以，要格外注意 `l` 在元音之后的情况，注意舌尖位置正确，动作完整，不能有嘴唇动作 —— 否则就会出现 `ʊ` 音。
 
 ![](/images/speech-tract-l.svg)
+
+<img src="/images/speech-tract-l.svg" class="themed"/>