What does it mean by visibility: hidden\ 9;?

an element uses css3"s rotate (), because ie8 does not support it, so the requirement hides this element in ie8 and displays it normally in other browsers. So use this style visibility: hidden 9; but no matter what version of IE it is, it hides the element (I just want to hide it in ie8), I want to ask, is there any other way to write it? what is the principle of 9? If there is any detailed article or explanation, please ask for advice

Css
Feb.28,2021

this is for compatibility with IE's css hack-- link description


< H2 > I. cause analysis < / H2 >

(1) first use "\ 9" for CSS hack (to write the corresponding CSS code for different browsers / different versions), if you need to know more. Check out front-end interview questions-CSS Hack

(2) "\ 9" is valid for both IE6 / IE7 / IE8 / IE9 / IE10, which is inconsistent with the requirement that it only works in IE8 style.

< H2 > II. Solution < / H2 >

(1) if you only need to hide elements in IE8, you must hack for IE8.

(2) our thinking can be changed: first apply IE8's hack, separate from non-IE browsers, and then apply some selector that IE8 does not support, such as CSS3, to cover it again, so that the IE9 and IE10 that support the new selector are displayed normally.

(3) the last common selector that meets the criteria is : root .

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b320e5-2bdf0.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b320e5-2bdf0.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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