You can easily design your own invoice layout with your own logo, font, and even a custom background.
Go to Settings (Gear icon) → Settings → Invoices.
Click on "+ New Layout".
You are now on the page where you can design your own invoice layout. Here you can change the font, font size, position of the sender and recipient addresses, add a logo/background, and modify the footer.
Once you have everything set up, this invoice layout will be used by default when creating your invoices.
Please note that if you upload a background, it will only become visible after you have sent or downloaded the invoice.
If you want to make further formatting changes, you can do so using CSS. We explain how to do this in the article "Customizing Layout of Invoices/Quotes with CSS."