What are the correct file type and size for the website logo image?

Only JPG and PNG image files may be uploaded. The logo image must have at least 300px in width and 40px in height. The image can be uploaded in Website > Theme, either

• via the link '(Basic) Customize this theme' > section 'Header Options' > Website Logo > Image (video tutorial),
• or via the link '(Advanced) Theme Builder' > 'Header' in the menu to the left of the page that opens > Branding > Your logo (video tutorial).