I have given the app for security review and I got a report saying "Lightning: Improper CSS load"  and the Issue definition is 
"To reference an external CSS resource that you’ve uploaded as a static resource, use a <ltng:require> tag in your .cmp or.app markup. Do not use <link> tags to load CSS resources.
For LWC, use loadStyle or loadScript" 
Where ever external CSS are used I have added it using  <ltng:require> tag and other CSS are inside component style sheet.

I tried integrating Salesforce with VS code.. I installed Salesforce CLI and when I tried creating a project in VS code but it says that Salesforce CLI is not installed.
 The exact error is

"14:48:25.402 sfdx force:project:create --projectname TestProject --outputdir d:\ --manifest
'sfdx' is not recognized as an internal or external command,
operable program or batch file.
14:48:25.492 sfdx force:project:create --projectname TestProject --outputdir d:\ --manifest ended with error spawn sfdx ENOENT
Salesforce CLI is not installed. Install it from https://developer.salesforce.com/tools/sfdxcli"