这是来自Chrome商店的 Seesponsive 浏览器插件，您可以在当前页面下载它的最新版本安装文件，并安装在Chrome、Edge等浏览器上。
(2) 从设置->更多工具->扩展程序 打开扩展程序页面，或者地址栏输入 Chrome://extensions/ 按下回车打开扩展程序页面
Seesponsive is a simple Google Chrome extension that allows you to see how a website's layout and design adjust responsively as the available screen width changes. It also lets you see the media queries that are being progressively matched or unmatched, driving these changes.
To use the extension, just browse to a website that uses media queries. Then click the extension's action button in the toolbar. After a few seconds a black action bar will appear at the top of the page with two buttons - Shrink and Grow.
Clicking these will shrink and grow the width of the website to simulate the device width changing. As this occurs the action bar will indicate which media queries are being matched/unmatched at a particular width.
To see some examples of sites that use media queries to adapt responsively visit Media Queries (http://mediaqueri.es/).
Note: The Media Queries website is not in anyway affiliated with, nor does it endorse this extension. It's just a really useful website that I've used in the screenshots purely for demonstration purposes.
Occasionally you may find that the loading message does not disappear and you get an error popup. This is an known intermittent issue at the moment. Usually reloading the page and trying again solves it.
This extension is open source under the MIT licence. See the Github project for details and code: