Fundamentally there's no reason to fight a user's DPI settings. If i set Windows to 200dpi and run at a high resolution, then the browser will work.
Your web-site will also work, you don't have to change anything.
The only thing you might want to deal with is the fact that my higher resolution monitor can display higher resolution images, but you continue to feed me those low resolution 540x120 logos.
Making the Web Bigger: DPI Scaling and Internet
There are times when you might want to know at which DPI Scaling a user is viewing your Web page. You can find this information by querying the screen.deviceXDPI or screen.deviceYDPI DOM property. For example, if the page is zoomed to 125%, screen.deviceXDPI will return 120 (120/96 equals 1.25, or 125%). Note, however, that the value returned is entirely dependent on the zoom state of Internet Explorer and not necessarily the DPI Scaling Setting of Windows. For example, if your Windows DPI Scaling is set to 144 DPI and you are viewing a Web page at 100% zoom, screen.deviceXDPI will return 96 (96/96 equals 1, or 100%), not 144.
Once you have the DPI information, you can:
- Make layout tweaks to optimize for different DPIs.
- Swap in higher-resolution images to take advantage of the extra pixels available to you (thus avoiding the use of imperfect image interpolation).
- Place elements on a Web page relative to the browser chrome.
It's like asking users not to browse your web-site on a Retina Display iPhone because its resolution is too high.