- Login/register now use CSS variables (--surface-*, --text-*, --accent)
- Dark/light theme toggle on auth pages (synced with localStorage)
- Unified nav menu: Главная, Инструменты, Возможности across all pages
- Consistent header style (backdrop blur, border)
- White background, card-style forms
- Fixed top header: logo, nav links (Главная, Инструменты, Возможности), login/register buttons
- Active state highlighting for current page
- Placeholders in inputs, password hint
- Mobile responsive (nav hidden on small screens)
- Red error styling matching light theme