You can change the background color, border color, and text color of product messages. Each phase (Before selling period, During selling period, After selling period) can be customized individually.
Open "Settings" from the left menu
Open the section for the phase you want to change
Configure the following:
Background: background color of the product message
Border: border color of the product message
Text: text color
Save
There is no built-in centering feature, but you can achieve this using custom CSS in the theme editor.
Navigate to Online Store > Themes > Customize
Select "Home page > Products > Default product" from the selector at the top center of the theme editor
Select the product information section on the left side of the theme editor
Enter the sample code in the custom CSS field
Click "Save" in the top right
sample code
If you want to make the product message background transparent, this may be achievable using custom CSS in your theme. For more details, please contact support.