- Go to your Store Control Panel → Design.
- Scroll down to the Сreate Your CSS Theme block.
- Click Create Theme:
If this is your first custom CSS theme, click Add New CSS Theme:
If you already have a custom theme with CSS codes, add the new codes to that theme. Paste the new codes under the old ones.
Click Activate to enable the new theme:
Click Save in the top right or press Ctrl + S.
TIP: Only one CSS theme can be active at a time, so all codes you want to use should be included in one theme.