Constant THEME_PRELOAD_SCRIPT 

const THEME_PRELOAD_SCRIPT: &str = r#"
(function() {
    try {
        var theme = localStorage.getItem('yggdrasil-theme');
        if (theme === 'dark' || (!theme && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
            document.documentElement.classList.add('dark');
        }
    } catch (e) {}
})();
"#;