I have a VF page created for Salesforce classic using Lightning Design System. The page works fine in Classic. But when I try to view it in Lightning Experience, it doesn't load (CSS) properly. Any reasons for the issue? I have enabled the 'Available for Lightning Experience, Lightning Communities, and the mobile app' checkbox as well. Please note that I added static resource to load the LDS css too but it didnt work out.
<apex:page id="sConfigId" controller="VF_Controller" showChat="false" showHeader="true" sidebar="false" standardStylesheets="false" applyBodyTag="false" applyHtmlTag="true" showQuickActionVfHeader="false" docType="html-5.0">
<head>
<title>Title</title>
<apex:includeScript value="{!URLFOR($Resource.SR_SR, '/js/jquery-1.12.3.min.js')}"/>
<apex:includeScript value="{!URLFOR($Resource.SR_Connect, '/js/jquery-ui.js')}"/>
<apex:stylesheet value="{!URLFOR($Resource.SR_Connect, '/css/jquery-ui.css')}" />
<!-- Import aljs and momentjs for Date pickers -->
<apex:includeScript value="{!URLFOR($Resource.SR_Connect, '/js/jquery.dataTables.min.js')}"/>
<apex:includeScript value="{!URLFOR($Resource.SR_Connect, '/js/dataTables.colReorder.min.js')}"/>
<apex:stylesheet value="{!URLFOR($Resource.SR_Connect, '/css/jquery.dataTables.min.css')}" />
<!-- Import Datatables and jquery -->
<!-- Import aljs and momentjs for Date pickers -->
<!-- Import SDLS -->
<apex:slds />
</head>
lightningStylesheets
. This will work ok if you have used standard apex tags in your page. Any custom styles my still need updating to work with lightning version though.