diff --git a/src/Popup.scss b/src/Popup.scss
index 4f055c9..2b2c8cb 100644
--- a/src/Popup.scss
+++ b/src/Popup.scss
@@ -73,8 +73,6 @@ body {
     background-color: var(--bg-color);
     margin: 0px 0px;
     padding: 0px;
-    display: flex;
-    flex-direction: column;
     min-width: 300px;
     max-width: 800px;
     max-height: 600px;
@@ -86,16 +84,7 @@ body.startup {
     height: var(--startup-height)!important;
 }
 
-body > :first-child {
-    flex: 0 0 auto;
-}
-
-body > :nth-child(2) {
-    flex: 1 1 auto;
-}
-
 body > :nth-child(3), body > :nth-child(3):hover,  body > :nth-child(3):focus, body > :nth-child(3):active {
-    flex: 0 0 auto;
     box-sizing: content-box;
     border-top-width: 1px!important;
     border-top-color: var(--line-color);
diff --git a/src/Popup.tsx b/src/Popup.tsx
index e405042..b5b1488 100644
--- a/src/Popup.tsx
+++ b/src/Popup.tsx
@@ -5,8 +5,10 @@ import PopupHeader from './components/PopupHeader';
 import PopupContainer from './components/PopupContainer';
 import PopupFooter from './components/PopupFooter';
 import ContextMenu from './components/ContextMenu';
+import { applyTheme } from './utils/theme';
 import './Popup.scss';
 
+
 interface PopupProps {
     config: Configuration
 }
@@ -62,52 +64,4 @@ function adjustHeight(length: number) {
     const rootStyle = document.documentElement.style;
     const height = (length + 2) * 30;
     rootStyle.setProperty('--startup-height', (height > 600) ? '600px' : height + 'px');
-}
-
-function applyTheme(theme: 'auto' | 'light' | 'dark') {
-    const rootElm = document.documentElement;
-
-    const applyDarkTheme = () => {
-        rootElm.classList.add('theme-dark');
-        rootElm.classList.remove('theme-light');
-        chrome.action.setIcon({
-            path: {
-                "16": "/icons/qbm16-dark.png",
-                "32": "/icons/qbm32-dark.png"
-            }
-        });
-    }
-
-    const applyLightTheme = () => {
-        rootElm.classList.add('theme-light');
-        rootElm.classList.remove('theme-dark');
-        chrome.action.setIcon({
-            path: {
-                "16": "/icons/qbm16.png",
-                "32": "/icons/qbm32.png"
-            }
-        });
-    }
-
-    switch (theme) {
-        case 'light':
-            applyLightTheme();
-            break;
-        case 'dark':
-            applyDarkTheme();
-            break;
-        case 'auto':
-        default:
-            const mql = window.matchMedia('(prefers-color-scheme: dark)');
-            const colorSchemeTest = (e: MediaQueryListEvent | MediaQueryList) => {
-                if (e.matches) {
-                    applyDarkTheme();
-                } else {
-                    applyLightTheme();
-                }
-            };
-            mql.onchange = colorSchemeTest;
-            colorSchemeTest(mql);
-            break;
-    }
 }
\ No newline at end of file
diff --git a/src/components/PopupContainer/OptionsItem.tsx b/src/components/PopupContainer/OptionsItem.tsx
index cde7e9c..05ae109 100644
--- a/src/components/PopupContainer/OptionsItem.tsx
+++ b/src/components/PopupContainer/OptionsItem.tsx
@@ -20,22 +20,21 @@ export interface OptionsItem {
     type: 'radio' | 'checkbox';
     /** This item's options */
     options: Option[];
+    /** callback after value change */
+    callback?: (val: any) => void;
 }
 
 interface OptionsItemProps extends OptionsItem { }
 
-export default function OptionsItem({ name: itemName, storage, type, options }: OptionsItemProps) {
+export default function OptionsItem({ name: itemName, storage, type, options, callback }: OptionsItemProps) {
     const [value, setValue] = useState(options[0].value);
     const name = itemName.replace('_', '-');
 
     const saveValue = async (val: any) => {
-        chrome.storage.local.set({ [storage]: val })
-            .then(() => {
-                setValue(val);
-            });
-
-        if (itemName === 'root_folder') {
-            chrome.storage.local.set({ startup: [val, 18] });
+        await chrome.storage.local.set({ [storage]: val });
+        setValue(val);
+        if (callback && typeof callback === 'function') {
+            callback(val);
         }
     };
 
diff --git a/src/components/PopupContainer/OptionsPage.tsx b/src/components/PopupContainer/OptionsPage.tsx
index 72e2ad2..e5729f0 100644
--- a/src/components/PopupContainer/OptionsPage.tsx
+++ b/src/components/PopupContainer/OptionsPage.tsx
@@ -1,6 +1,7 @@
 import { h } from 'preact';
 import { useEffect, useState } from 'preact/hooks';
 import OptionsItemComponent, { OptionsItem } from './OptionsItem';
+import { applyTheme } from '../../utils/theme';
 import "./OptionsPage.scss";
 
 const optionsItems: OptionsItem[] = [
@@ -92,7 +93,10 @@ const optionsItems: OptionsItem[] = [
         name: 'root_folder',
         storage: 'root',
         type: 'radio',
-        options: [{ name: '', value: '0' }]
+        options: [{ name: '', value: '0' }],
+        callback: (val) => {
+            chrome.storage.local.set({ startup: [val, 18] });
+        }
     },
     {
         name: 'color_theme',
@@ -111,7 +115,10 @@ const optionsItems: OptionsItem[] = [
                 name: 'dark',
                 value: 'dark',
             }
-        ]
+        ],
+        callback: (val) => {
+            applyTheme(val);
+        }
     },
     {
         name: 'scroll_layout',
diff --git a/src/components/PopupContainer/PopupContainer.scss b/src/components/PopupContainer/PopupContainer.scss
index 78ff2b4..1081d08 100644
--- a/src/components/PopupContainer/PopupContainer.scss
+++ b/src/components/PopupContainer/PopupContainer.scss
@@ -4,6 +4,7 @@
     position: relative;
     max-width: 800px;
     min-width: 300px;
+    max-height: 538px;
 
     &-horiz {
         overflow-x: auto;
diff --git a/src/utils/theme.ts b/src/utils/theme.ts
new file mode 100644
index 0000000..8d0b673
--- /dev/null
+++ b/src/utils/theme.ts
@@ -0,0 +1,51 @@
+let mql: MediaQueryList | null = null;
+
+export function applyTheme(theme: 'auto' | 'light' | 'dark') {
+  const rootElm = document.documentElement;
+
+  const applyDarkTheme = () => {
+    rootElm.classList.add('theme-dark');
+    rootElm.classList.remove('theme-light');
+    chrome.action.setIcon({
+      path: {
+        "16": "/icons/qbm16-dark.png",
+        "32": "/icons/qbm32-dark.png"
+      }
+    });
+  }
+
+  const applyLightTheme = () => {
+    rootElm.classList.add('theme-light');
+    rootElm.classList.remove('theme-dark');
+    chrome.action.setIcon({
+      path: {
+        "16": "/icons/qbm16.png",
+        "32": "/icons/qbm32.png"
+      }
+    });
+  }
+
+  switch (theme) {
+    case 'light':
+      applyLightTheme();
+      break;
+    case 'dark':
+      applyDarkTheme();
+      break;
+    case 'auto':
+    default:
+      const colorSchemeTest = (e: MediaQueryListEvent | MediaQueryList) => {
+        if (e.matches) {
+          applyDarkTheme();
+        } else {
+          applyLightTheme();
+        }
+      };
+      if(!mql) {
+        mql = window.matchMedia('(prefers-color-scheme: dark)');
+        mql.addEventListener("change", colorSchemeTest);
+      }
+      colorSchemeTest(mql);
+      break;
+  }
+}
\ No newline at end of file