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HTML centering

Windows : Internet Explorer 3.0+, Firefox 1.0+, Google Chrome, Opera 3.51 - 6.xx and 9.0+, Safari 3.1+, SeaMonkey 1.0+ [ 1 ].

Linux : Firefox 1.0+, Chromium, Opera 5.0 - 6.xx and 9.0+, SeaMonkey 1.0+ [ 2 ].

Centering the whole content of a web page in the viewable area of a browser by pure HTML - no CSS. A box to keep the content of the page is HTML centered horizontally and vertically - [ Open demo page ]

HTML. Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>HTML centering</title>

<meta http-equiv="Content-Type" content="text/html; charset=Windows-1252">

</head>

<body bgcolor="#ffffff">

<table width="100%" height="100%" bgcolor="#a3ddc4">

<tr>

<td align="center">

<table width="800" height="500" bgcolor="#ff6f6f">

<tr>

<td>&nbsp;</td>

</tr>

</table>

</td>

</tr>

</table>

</body>

</html>

The outer HTML table makes the whole web browser viewable area, except margins, a HTML table and the whole area of this HTML table - a HTML table cell.

The cell of the outer HTML table inherits the default value for valign attribute from its parent table row. And this row in its turn inherits the default value for valign attribute from the outer HTML table tbody - even if tbody tag is not used. And that value is middle. So a block of content inside the cell of the outer HTML table is centered vertically in web browser viewable are.

Align="center" of the outer HTML table cell makes a block of content inside it centered horizontally in web browser viewable are.

The inner table, the one inside of the outer HTML table cell makes up a box of a given size. Or there may be no set height or no set width or both. Then the size of the box is to adjust to accommodate the content, whatever its dimensions are. If the width or height or both of the box results to be larger than web browser viewable area, then it still ends up to be centered.

Since HTML centering is the oldest method to center content horizontally and vertically, it works well not just in older web browsers, but in ones that can be described as downright ancient. Like adding one more HTML tag ( <center></center> ) around the outer table makes it funcion as deep as Internet Explorer 3 : [ Open demo page ]

Download Internet Explorer 3: a pack, containing 3.0, 4.01, 5.01, 5.5, 6.0 versions of Internet Explorer

HTML. Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>HTML centering for Internet Explorer 3</title>

<meta http-equiv="Content-Type" content="text/html; charset=Windows-1252">

</head>

<body bgcolor="#ffffff">

<!-- For Internet Explorer 3 --><center><!-- For Internet Explorer 3 -->

<table width="100%" height="100%" bgcolor="#a3ddc4">

<tr>

<td align="center">

<table width="800" height="500" bgcolor="#ff6f6f">

<tr>

<td>&nbsp;</td>

</tr>

</table>

</td>

</tr>

</table>

<!-- For Internet Explorer 3 --><center><!-- For Internet Explorer 3 -->

</body>

</html>

HTML horizontal and vertical centering of a box containing web page content has become obsolescent as a result of semantic markup spread. But it is still reliable. Not only in the major and modern web browsers, but in many alternative and older ones as well.

There is a minor flaw in it though. The height attribute of the <table><table/> tag is used there. It is supported for years by the majority of web browsers, but is incompatible with the standards promoted by World Wide Web Consortium (W3C). So the code does not pass W3C validation. Back in 1990s - early 2000s, it was complicated or impossible to succeed in making a code both valid and working in the majority of web browsers, so the flaw was not looked at as a real problem.


[ 1 ]

As well as Netscape 2.02 - 4.80 and Offbyone. There is some shift of page content to the top left corner of the web browser viewable area in Netscape 2.02 - 4.80, since these web browsers reserve the place for scrollbars.

[ 2 ]

As well as Netscape 2.02 - 4.80. There is some shift of page content to the top left corner of the web browser viewable area in Netscape 2.02 - 4.80, since these web browsers reserve the place for scrollbars.


Aliosque subditos et thema

 

CSS. Target Opera only

 

CSS targeting Opera web browser only: This text is red in Opera HTML / XHTML. Code: <p>This text is red in Opera</p> CSS. Code: doesnotexist:-o-prefocus, p {color: #f00;} The -o-prefocus pseudo-class allows styling elements for Opera browser only. The code is placed in the common CSS file, not in a separate one as it is in case of Internet Explorer conditional comments. Source: http://www.opera.com/docs/specs/presto2.12/css/o-vendor/ [ 1 ] Opera 3.5 - 5.0 ignores "doesnotexist:-o-prefocus" and reads code as p {color: #f00;}. Opera 6.0 - 9.4 ignores the whole code starting "doesnotexist". [ 2 ] Internet Explorer 5.5+, Firefox 1.0+, Google Chrome, Safari 3.1+, SeaMonkey 1.0+, Netscape 7.2+, Mozilla 1.5+ ignore the whole code starting "doesnotexist". Older browsers like Internet Explorer before 5.5 or Netscape before 7.2 or Mozilla before 1.5 seem to ignore the uncommon, Opera 9.5+ specific code ("doesnotexist:-o-prefocus") and apply styles to what they understand - here it is the p tag; making the text in it red. [ 3 ] The text is red in Dillo 3.0.1 as well.

CSS horizontal and vertical centering - 1

 

Centering the content of a web page in the viewable area of a browser by means of CSS. A box to contain the whole content of the page is CSS centered horizontally and vertically: [ Open demo page ] HTML / XHTML. Code: <!DOCTYPE html> <html> <head> <title>CSS horizontal and vertical centering - 1</title> <link rel="stylesheet" type="text/css" href="css.css" /> </head> <body> <div class="all"> <div class="wrapper"> <div class="pagecontent">&nbsp;</div> </div> </div> </body> </html> CSS. Code: html {height: 100%; margin: 0px;} body height: 100%; margin: 0px;} .all {position: relative; left: 0px; top: 0px; height: 100%; width: 100%; float: left; display: table;} .wrapper {position: relative; left: 0px; top: 0px; height: auto; width: 100%; display: table-cell; vertical-align: middle;} .pagecontent {position: relative; left: 0px; top: 0px; height: 500px; width: 800px; margin: 0 auto; background: #ff6f6f;} The .pagecontent box is for the page content. It may be of height assigned explicitly or just "height: auto". Unlike CSS horizontal and vertical centering - 2, here percents may also be used as CSS units; not just px's or em's. Height and width may be larger than web browser viewable area, but here the more practical case is discussed - when the height and width of .pagecontent are smaller than those of the web browser viewable area. The .pagecontent box is horizontally centered by its "margin: 0 auto". .All with its CSS properties makes the whole web browser viewable area into a CSS table. CSS properties makes .wrapper into the cell of this CSS table. The content of this CSS table cell - the .pagecontent box with everything inside it - is vertically centered in the viewable area of a browser by "vertical-align: middle". [ 1 ] As well as Netscape 7.2+, Mozilla 1.5+. [ 2 ] As well as Netscape 7.2+, Mozilla 1.5+.