(function() {
    try {
        const saved = localStorage.getItem('theme');
        const osPref = matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
        document.documentElement.setAttribute('data-theme', saved || osPref);
    } catch (e) {
        document.documentElement.setAttribute('data-theme', 'light');
    }
})();