How to Change Letter Spacing on Form Button on 7.1

Site URL: https://rachelle-bella.squarespace.com/

Hello!

I've been trying out the new Squarespace 7.1 templates and I'm not really liking it too much. I was hoping someone could help me figure out the CSS to change the contact form button's LETTER SPACING.

Site: https://rachelle-bella.squarespace.com/
Password: bella

Would love some help! This is a whole new system to learn and code.

Add to Home > Design > custom CSS

input.button.sqs-system-button.sqs-editable-button {
    letter-spacing: 5px;
}

@tuanphan you rock!