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CSS centering absolutely positioned elements

Windows : Internet Explorer 8.0+, Firefox 1.0+, Google Chrome, Opera 5.0+, Safari 3.1+, SeaMonkey 1.0+ [ 1 ].

Linux : Firefox 1.0+, Google Chrome / Chromium, Opera 5.0+, SeaMonkey 1.0+ [ 2 ], NetSurf 2.6+.

CSS horizontal centering of an absolutely positioned element. Example:

Image

HTML / XHTML. Code:

<div class="example">

<img src="image.jpg" alt="Image" />

</div>

CSS. Code:

.example {position: relative; left: 0px; top: 0px; height: 90px; width: 100%; float: left; padding: 10px; border: 1px #ccc solid; background: #fafafa; -moz-box-sizing: border-box; -webkit-box-sizing: border-box; -ms-box-sizing: border-box; box-sizing: border-box;}

.example img {position: absolute; left: 0px; right: 0px; margin: 0px auto; width: 68px;}

An absolutely positioned img is centered in the example. But this method of horizontal centering also works with other both inline and block absolutely positioned elements.

The width of an absolutely positioned element may also be in percent or other units.

CSS properties of a container (here it is .example), holding an element to be centered, may vary. The element's centering is achieved by styles applied to the element itself: .example img {position: absolute; left: 0px; right: 0px; margin: 0px auto;}.


[ 1 ]

As well as Netscape 8.01+, Mozilla 1.5+.

[ 2 ]

As well as Netscape 8.01+, Mozilla 1.5+.


Aliosque subditos et thema

 

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+.

HTTPS to HTTP redirect for a single page

 

Redirecting a single page with HTTPS to the page with HTTP. Server configuration: Apache + nginx. SSL is enabled for the whole web site, so all pages are served with HTTPS. But there is a need to make just one single page to be with HTTP. Directives for .htaccess file: RewriteEngine On RewriteCond %{HTTP:HTTPS} on [NV] RewriteRule ^(page\.html)$ http://%{HTTP_HOST}/$1 [R=301,L,QSA] HTTPS to HTTP redirect for a single page in detail -- Enable runtime rewriting engine RewriteEngine On -- If HTTPS is present RewriteCond %{HTTP:HTTPS} on [NV] -- Then, when a page name and extension correspond to the search group in parentheses, form for it a URI with HTTP RewriteRule ^(page\.html)$ http://%{HTTP_HOST}/$1 [R=301,L,QSA] Notes RewriteCond %{HTTP:HTTPS} on [NV] is not the only way to detect if HTTPS is present. Moreover, for some server configurations other directives may be more suitable, like RewriteCond %{SERVER_PORT} 443 for example. The point is to find out somehow if HTTPS is on. So it should probably be checked by practice what is going to work in a particular case. QSA is used to keep the existing query string, if there is any, when the replacement URI also contains a query string. So that in the end both query strings are to be combined. More on the subject: http://httpd.apache.org/docs/2.2/rewrite/flags.html#flag_qsa