I'm trying to create a table "With No Borders" using standard lightning-datatable of LWC.
I'm referring to the pieces of codes given in https://www.lightningdesignsystem.com/components/data-tables/#With-no-borders and https://developer.salesforce.com/docs/component-library/bundle/lightning-datatable/example.
One thing I have understood that I have to have to see the magic.
I tried accessing thead using this.template.querySelectorAll('thead')[0] and adding class in it as
this.template.querySelectorAll('thead')[1].class="slds-assistive-text";
But I couldn't achieve the desired result. So can anyone please help me regarding it? Let me know what I'm missing, or is it not possible to achieve this at all.
Note: I have defined class="slds-table slds-table_cell-buffer slds-table_header-hidden" at data-table component itself.