Input field for numbers should have type `number`
The input fields for numbers (like stock, price, weight, and so on) should have the type
number as well, instead of
text. This would allow the usage of the comma as a decimal delimiter, which is usually used in German.
This concerns the options, product options, and download options UI.
Furthermore, the styling of these input fields needs to be changed, so that the up and down arrows aren't shown in the input fields.
For more information see: https://www.w3schools.com/howto/howto_css_hide_arrow_number.asp