After upgrade to Winter 21, I found Lightning Design System show weird in IE-11. Please see follow image.
And this is my code.
<apex:page sidebar="false" lightningStylesheets="true" showHeader="false" docType="html-5.0">
<apex:slds></apex:slds>
<button class="slds-button">Button</button>
<button class="slds-button slds-button_neutral">Neutral Button</button>
<button class="slds-button slds-button_brand">Brand Button</button>
<button class="slds-button slds-button_outline-brand">Outline Brand Button</button>
<button class="slds-button slds-button_destructive">Destructive Button</button>
<button class="slds-button slds-button_text-destructive">Text Destructive Button</button>
<button class="slds-button slds-button_success">Success Button</button>
</apex:page>
You can see all SLDS style not work.
I check Winter 21 Release Note and I found "Customize Components with Lightning Design System Styling Hooks (Beta)" update in Lightning Design System. Here is the Link: https://releasenotes.docs.salesforce.com/en-us/winter21/release-notes/rn_slds_styling_hooks.htm
In this document I found follow content:
Styling hooks make it easy to customize component styling and express your brand, especially when working with web components and shadow DOM. For a list of component blueprints that support styling hooks, see the Lightning Design System website.
As far as I know IE-11 not support this feature, please see this link: https://developer.mozilla.org/en-US/docs/Web/CSS/var
And I try open Lightning Design System's Button component page in IE-11, but I got a blank area.
But it's work fine in Chrome.
Since this is a beta function may I ask how to disabled it?
Best wishes, Lee