/*
  No-flash theme init (external so a strict CSP can use script-src 'self' with no
  inline hash). Loaded render-blocking in <head>, runs before first paint: marks
  that JS is available (reveal animations are gated behind html.js) and applies the
  stored or system theme. First visit follows the system; once set, the choice persists.
*/
(function () {
  document.documentElement.classList.add('js');
  try {
    var t = localStorage.getItem('theme');
    if (t !== 'light' && t !== 'dark') {
      t = window.matchMedia('(prefers-color-scheme: light)').matches ? 'light' : 'dark';
    }
    document.documentElement.dataset.theme = t;
  } catch {
    document.documentElement.dataset.theme = 'dark';
  }
})();
