What is this about?

Layout Mode Test

The doctype used on this page is <?xml version="1.0" encoding="UTF-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

This page has no X-UA-Compatible meta element.

This page has no X-UA-Compatible HTTP header.

Note: Be sure to observe the test that is applicable to the browser you are using.

Interoperable Quirks test (not applicable to old Opera, old Safari Mac IE 5 or Windows IE 6 or 7)

The browser is in the Standards or Almost standards Quirks mode.

IE 5.5-Style Quirks indicator (applicable to Mac IE 5, Windows IE 6…9, IE10 relative to IE10 Quirks and Opera 7 & 8

Quirk reference
Test
Standard reference

Almost Standards indicator (not applicable to Opera older than 7.5, Mac IE 5 or Windows IE 6 & 7)

Standards if the blue rectangles are a couple of pixels taller than a line of text. Almost standards or quirks if the rectangles are 3px tall.

Pre-HTML5 WebKit Test

The browser is not in the Standards or Almost Standards mode. It is in the Quirks mode.

IE8…10 Compatibility View (IE7 mode) test

The compatibility view is enabled.

IE9 mode test

If diamond below, the mode is at least IE9 mode

IE10 mode test

If diamond below, the mode is at least IE10 mode

Safari v60 Test (not applicable to Safari v73!)

Red if quirks

document.compatMode

document.documentMode