Hi comunicazione,
Thanks for reaching to us.
1. First you need to create Custom Header for single products, then navigate to WoodMart > Header builder > edit default header (highlighted star icon) or you can go through the admin bar directly https://prnt.sc/Ct9ehRDvvDV9
Click on the Settings icon of Main header https://prnt.sc/6OIKfJKG_OeD > Style tab > and you can change background color https://prnt.sc/vdtEAb9YP9Mc
Please refer to documentation for more details:
https://xtemos.com/docs-topic/woodmart-header-builder/
2. Use our Theme Presets to define the site width for a specific condition, here is our documentation on how to use theme presets: https://xtemos.com/docs-topic/theme-settings-presets/
For the preset, try to use this condition https://prnt.sc/pTzKMrL38No0 Click on Edit theme settings > go to General > Layout and select custom header https://prnt.sc/reN9IoDDKcZc
Don’t hesitate to let me know if you need any further help or any other info.
Regards,
.
