Chrome Popup Window Size: How to Override Limits

TL;DR

Chrome often restricts how small popup windows can be. This guide shows you several ways to bypass these limits, from using CSS and JavaScript to modifying the manifest file.

Solution Guide

1. Understand the Problem: Chrome enforces minimum size restrictions on popups for usability reasons. Trying to set a window smaller than this can be ignored or cause unexpected behaviour.
2. CSS Approach (Simplest): Sometimes, simply adjusting CSS styles within your popup’s HTML can influence its initial size.
   • Try setting explicit width and height properties on the body element:

     body { width: 100px; height: 50px; }

   • If you’re using a framework like Bootstrap, ensure its default styles aren’t overriding your size settings. Inspect the elements in Chrome DevTools to check.
3. JavaScript Approach (More Control): Use JavaScript to control the window dimensions after it opens.
   • Get the current window object:

     const popupWindow = window;

   • Set the width and height. Note that this might not work immediately if Chrome is still enforcing its minimums, but can be effective after a short delay.

     popupWindow.resizeTo(100, 50);

   • Alternatively, try setting the window’s inner width and height:

     popupWindow.innerWidth = 100; popupWindow.innerHeight = 50;

4. Manifest File Modification (Advanced): You can adjust the content_security_policy in your Chrome extension’s manifest file, but this is generally not recommended unless you understand the security implications.
   • Open your manifest.json file.
   • Locate the content_security_policy key. If it doesn’t exist, add it.
   • Modify the policy to allow more flexible sizing (use with caution!):

     "content_security_policy": "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'

     Warning: Relaxing the CSP can introduce security vulnerabilities. Only do this if you fully understand the risks and are confident in your code.

5. Using a Hidden Iframe (Workaround): Create an iframe within your popup, set its size to be very small, then display content inside it.
   • Add an iframe element to your HTML:

     <iframe id="myIframe" src="your-content.html" style="width: 100px; height: 50px; border: none;"></iframe>

   • Load your content into the iframe. The popup window size will be determined by the iframe’s dimensions.
6. Check for Conflicting Stylesheets/Frameworks: Ensure that other CSS files or frameworks aren’t overriding your desired sizes.
   • Use Chrome DevTools to inspect the elements and identify any conflicting styles.
7. Test Thoroughly: After making changes, test your popup in different Chrome versions and on various screen resolutions to ensure it behaves as expected.