src/components/ThemeToggle.astro

---
import { Sun, Moon } from 'lucide-astro';
---

<button 
  class="relative p-2 text-white hover:text-blueprint-accent transition-colors duration-300 rounded-lg hover:bg-white/10 overflow-hidden"
  data-theme-toggle
  aria-label="Toggle dark/light theme"
>
  <div class="relative w-5 h-5">
    <Sun class="w-5 h-5 absolute inset-0 transition-all duration-500 transform" data-sun-icon />
    <Moon class="w-5 h-5 absolute inset-0 transition-all duration-500 transform" data-moon-icon />
  </div>
</button>

<script>
  function initTheme() {
    const themeToggle = document.querySelector('[data-theme-toggle]');
    const htmlElement = document.documentElement;
    const sunIcon = document.querySelector('[data-sun-icon]') as HTMLElement;
    const moonIcon = document.querySelector('[data-moon-icon]') as HTMLElement;
    
    // Get saved theme or default to dark
    const savedTheme = localStorage.getItem('theme') || 'dark';
    
    // Function to update icons with animation
    function updateIcons(isDark: boolean) {
      if (isDark) {
        // Dark mode - show moon, hide sun
        sunIcon.style.transform = 'rotate(180deg) scale(0)';
        sunIcon.style.opacity = '0';
        moonIcon.style.transform = 'rotate(0deg) scale(1)';
        moonIcon.style.opacity = '1';
      } else {
        // Light mode - show sun, hide moon
        moonIcon.style.transform = 'rotate(-180deg) scale(0)';
        moonIcon.style.opacity = '0';
        sunIcon.style.transform = 'rotate(0deg) scale(1)';
        sunIcon.style.opacity = '1';
      }
    }
    
    // Apply theme
    if (savedTheme === 'dark') {
      htmlElement.classList.add('dark');
      updateIcons(true);
    } else {
      htmlElement.classList.remove('dark');
      updateIcons(false);
    }
    
    // Theme toggle functionality
    themeToggle?.addEventListener('click', () => {
      const isDark = htmlElement.classList.contains('dark');
      
      if (isDark) {
        htmlElement.classList.remove('dark');
        localStorage.setItem('theme', 'light');
        updateIcons(false);
      } else {
        htmlElement.classList.add('dark');
        localStorage.setItem('theme', 'dark');
        updateIcons(true);
      }
    });
  }

  // Initialize on DOM load
  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', initTheme);
  } else {
    initTheme();
  }
</script>