What is the issue?
SharePoint 2010 and 2007 require Internet Explorer to operate in compatibility mode to ensure smooth functionality with various browser objects. This includes features such as viewing lists in datasheet view or opening files directly in Excel.
However, compatibility view in these versions of Internet Explorer follows HTML and CSS standards similar to that of IE8. This means that certain advanced CSS selectors like
#slideshow-wrap input[type=radio]#button-5:checked~#slideshow-inner>ul
and properties like
@font-face may not function correctly.
For a comprehensive list of which CSS3 properties are supported by different browser versions, refer to this CSS3 reference link: http://www.w3schools.com/cssref/css3_browsersupport.asp
Additionally, it's important to note that IE8 does not fully support CSS3 selectors - only CSS1 and CSS2. You can find more information on CSS selectors at this link: http://www.w3.org/TR/selectors/#selectors
How can this be resolved?
To address this issue, you have two options. You can either make your code compatible with older versions of Internet Explorer or update the masterpages in SharePoint sites with a meta tag that enforces Edge mode instead of IE8.
Switching to Edge mode will allow you to leverage modern HTML and CSS capabilities but might disable IE8-specific ActiveX controls. Consider how users interact with your SharePoint environment before making any changes.
In SharePoint, it's possible to use different masterpages for different scenarios. You could create a custom masterpage specifically for modern HTML/CSS/JavaScript usage while retaining the IE8-mode masterpage for interactions involving SharePoint lists and libraries.