(function(){
  const root = document.documentElement;
  const stored = localStorage.getItem('theme');
  const prefersLight = window.matchMedia && window.matchMedia('(prefers-color-scheme: light)').matches;
  const initial = stored || (prefersLight ? 'light' : 'dark');
  if(initial === 'light') root.setAttribute('data-theme','light');

  const toggle = document.getElementById('themeToggle');
  const logo = document.getElementById('logoImg');
  function setLogo(){
    const isLight = root.getAttribute('data-theme') === 'light';
    if(logo){ logo.src = isLight ? './1.png' : './2.png'; }
  }
  setLogo();
  if(toggle){
    toggle.addEventListener('click',()=>{
      const isLight = root.getAttribute('data-theme') === 'light';
      if(isLight){
        root.removeAttribute('data-theme');
        localStorage.setItem('theme','dark');
      }else{
        root.setAttribute('data-theme','light');
        localStorage.setItem('theme','light');
      }
      setLogo();
    });
  }
})();