How do I change height of header or row to 100vh?

[ShareWordpress]

Hello, I want to ask, How can I add CSS to weebly and make header height: 100vh and responsive it?
I want to make it beautiful.

Thank you

[Adam7]

What's the address of your site, @ShareWordpress? If you're using a newer theme with a flexible header section you can just drag it shorter or taller (it's also already responsive).

[dc41]

Did you ever get it sorted out? I'm trying to have a full viewport header, but can't figure it out.