Confluence Themes Free |link|

Compare like Refined if your team grows beyond 10 users. Let me know which specific UI change you're trying to make! Themes for Confluence Cloud - Atlassian Community

While primarily for macros, Aura helps create a "themed" experience by adding beautiful backgrounds, buttons, and dividers that standard Confluence lacks. 3. Using Free Templates as a Theme Alternative

You can modify the navigation bar colors, background, and button accents at no cost to match your company branding.