Table of topic groups > Front page of CSS-guide > Extra pages > E What kind of non-standard (proprietary) CSS browsers support > DTD-switches (section 3/6)

Sections of page:

First section

Previous section

Next section

Last section

DTD-switches

In a way proprietary features are such features, which belong to the specifications, but implementations broke in purpose existing specifications. New MS IE and Netscape/ Mozilla browsers use DTD-switches, when with certain without DTD or with certain DTD new browsers work in some matters at the same way as older and more buggy browsers. Newer browsers support overall better CSS and HTML specifications and they are designed to work in certain modes better according to the CSS and (X)HTML specifications than in another mode.

Netscape/ Mozilla calls the better mode as the standard mode/ strict mode. The opposite is the quirks mode.

Microsoft calls the better mode as the standard-compliant mode, when the other mode is just the mode, where the standard-compliant mode has not been turned on. The "switching mechanism" is in MS IE 6.0 for Windows, MS IE 5.0 for Mac, Netscape 6.x/ corresponding Mozilla and Opera 7.x+ browsers.

In fact Opera 7.5x and newest Netscape/Mozilla browsers have a third mode (the Almost Standards mode).

Maybe the most remarkable effect is in MS IE browsers, where the switch affects calculating width and height properties in MS IE browsers. The system works quite well except calculating the width property in tables. In MS IE 5.0 for Mac the DTD-switch affects also to the width attribute of the TABLE element. MS IE 5.0 for Mac handles in the standard-compliant mode the width attribute like the corresponding property, which is an error at the sight of HTML (I handle these matters also in the page 10). In Mozilla Gecko and Opera 7.5x browser the standard and almost-standard mode differs each others when calculating the width of the table.

The switch cause also in MS IE into proprietary CSS. MS IE doesn't accept for example scroll bar properties in the standard-compliant mode. That's why pages, which are inside IFRAME and which have colored scroll bars, use DTD, which doesn't switch the standard-compliant mode on. Other pages work in new MS IE and Netscape/Mozilla according to strict/ standard-compliant modes.

I have found some differences and I have read from web pages about them. I found also that Netscape/ Mozilla defines non-standard behavior by using the quirk.css and a part of the information base also on that UA CSS file (differences, which are caused with this CSS-file are not general necessary to test). I have got also information through e-mails. The table below is not complete, but it mentions some possible differences (because I have not personally tested all listed matter, the table might have errors and I need help to get it better and the table doesn't make difference between the standard and almost-standard modes):

	MS IE 6.0 for Windows	MS IE 5.0 for Mac	Netscape 6.2.1	Opera 7.x
The first element inside BODY and TD elements have different top margins (concerning TD also the bottom margins of the last elements are different) if they are not set with CSS.			Yes (UA CSS)
width and height properties for generic block-level elements.	Yes	Yes
The width property for the TABLE element.		Yes	(Maybe)
The width property for TD and TH elements together with table-layout:fixed.	Yes	Yes
The need of display:inline-block for ordinary inline level elements together with width and height properties.	Yes
Applying CSS for the HR element.			Yes (UA CSS)
Different font size handling inside heading elements (H1 etc.).			Yes (prop. UA CSS)
Different wrapping of the PRE element.			Yes (prop. UA CSS)
The presentation of list elements is different.			Yes (UA CSS)
Different display type for the MAP element.			Yes (UA CSS)
Different margin for the IMG element, if the image has the align="left" or align:right attribute.			Yes (UA CSS)
Different handing of percentage heights on images and tables.			Yes
Background properties for table elements.			Yes (UA CSS)
Inheritance for most text related properties works/doesn't work for TABLE and CAPTION elements (font-size, font-weight, font-style, font-variant and for the element TABLE text-align).			Yes (partially prop. UA CSS)
When tables have a border style of inset or outset, the border color is based on the background color of the table or of the nearest ancestor with non-transparent background.			Yes (needs tests)
The empty-cells property defaults to hide/ show empty cells.			Yes (UA CSS)
Table cells with a border have a minimum width of one pixel.			Yes (needs tests)
The basic table layout strategy ignores/accepts paddings.			Yes (needs tests)
Floated tables never move/ move to the next "line" if they don't fit next to other floats (if they don't move to the next line they just keep widening the page).			Yes (needs tests)
Slightly different default presentation for INPUT elements.			Yes (UA CSS)
Browsers render font-size:xx-small - font-size:xx-large differently (look at Model8c.html).	Yes			Yes
The CSS parser accepts invalid names of id and class selectors.	Yes
The CSS parser reads @import even if it is not on the top of the style sheet.	Yes
The CSS parser accepts hexadecimal colors not beginning with #.	Yes		Yes
The CSS parser interprets unitless numbers as px (concerning Netscape browsers except for the font-size property because Netscape 4.x did according to the specifications; in general this matter doesn't concern the line-height property and any other properties where numeric values have distinct meaning).	Yes (but a buggy fixing)		Yes
Accepting of proprietary CSS.	Yes

Notes:

1. Netscape/ Mozilla has also some HTML element and attribute related matters, which can't change with CSS. I have tried to list such default settings, which can change equal with CSS (in most cases the behavior can set equal with standard CSS but in some cases changes might need proprietary CSS, which Netscape/ Mozilla use much in their UA CSS files; in principle it is possible to change with proprietary UA CSS stand behaviors into non-standard).
2. In the site of Mozilla org. according David Baron the basic table layout strategy handles widths differently in some way and Mozilla browsers. Because I didn't find any differences I put that matter into parenthesis. In principle Netscape/ Mozilla and MS IE 6.0 should have different handling of the width property with the TABLE element in the standard(-compliant) mode.
3. David says also, that Mozilla browsers have a minimal difference handling xx-small-xx-small values. I didn't find any difference in handling font-size:xx-small - font-size:xx-large. That's why I don't mention about any difference in this matter. The effect might be different in different versions and Netscape 6.2.1 just doesn't have this difference.
4. According to David the behavior of certain form control elements in Netscape/ Mozilla can alter also with some JavaScript encoding but I have tried to list only such features, which can be changed only by altering the DTD of the document.
5. I have listed some details also in the extra page, which handles CSS-implementation errors of MS IE browsers.
6. The switching point, where standard(-compliant) mode is on, is different in MS IE and Netscape/Mozilla browsers. In Netscape/ Mozilla browsers the strict mode starts from HTML 4.0 Strict or HTML 4.01 Transitional document types. In MS IE the standard-compliant mode starts from the HTML 4.0 Transitional document type, if the URL ("http://www.w3.org/TR/REC-html40/loose.dtd") has been given. If the URL has not been given standard-compliant mode starts from the HTML 4.0 Strict document type.
7. The DTD-declaration must be on the top of the page without anything before it. I had in the CSS-site in some pages before it a comment, when MS IE understood XHTML 1.0 Transitional documents so that the standard-compliant mode was off.

Sections of page:

First section

Previous section

Next section

Last section