White space below header

Hello @rajat-dutt,

You can add the following in Appearances > Customizer > Additional CSS:

/* Remove white margin bottom below the header   */

#masthead{
  margin-bottom: unset !important;
}

For step-by-step instructions, you can check this guide: https://wordpress.com/support/editing-css/#access-the-css-editor

Hope this helps! :?)